5th October 2019

How does lead cause CVD?

Following my last blog, several people asked the question. How does lead cause CVD – or atherosclerotic plaques? What is the mechanism of action? It’s a good question, one that I think I have answered before, at least in part. However, I think there is real value in going over it again.

First, I want to highlight some of the more general thinking about causes of CVD, I believe this is important as well, in order to see how lead fits in, and where my interest in lead came from.

For many, many, years now I have been trying to create a unified hypothesis about cardiovascular disease. A journey I thought I would never finish. Mainly, I now realise, because I kept coming across ever more ‘factors’ that had a role in CVD. This meant that – although I couldn’t quite work out why at first – I was running into the impossible, and unsolvable, problem.

246 factorial

The unsolvable problem is a direct result of the number of possible interactions between all the risk factors that have been identified.

To try and explain this further, I shall start with the latest UK risk factor calculator which is called Qrisk3. The previous one was Qrisk2. Qrisk3 can be found on-line here https://qrisk.org/three/ You can play with it to your heart’s content. Qrisk3 has moved on considerably from Qrisk1 and 2. It now incorporates twenty different factors.  If you strip them out of the algorithm they are, in no particular order:

• Age
• Sex
• Smoking
• Diabetes
• Total cholesterol/HDL ratio
• Raised blood pressure
• Variation in two blood pressure readings
• BMI
• Chronic kidney disease
• Rheumatoid arthritis
• Systemic Lupus Erythematosus (SLE)
• History of migraines
• Severe mental illness
• On atypical antipsychotic medication
• Using steroid tablets
• Atrial fibrillation
• Diagnosis of erectile dysfunction
• Angina, or heart attack in first degree relative under the age of 60
• Ethnicity
• Postcode

As a quick side-track, it amuses me that LDL is not in there – yet HDL is.

Now, you may think that this appears to be a relatively short list. At first sight it does not appear a complex task to fit these factors together into a coherent model. A twenty-piece jigsaw puzzle – at most?

Not so. The reality is that, if you view the model of CVD as twenty independent and unconnected risk factors, the number of possible interactions, or pieces, you need to analyse becomes mind-boggling.

Just to give you an idea of the scale of the maths involved here. You have twenty different risk factors, and you do not know how the connections between them work. Every risk factor can, potentially, interact with all the others – independently. This means that the possible combinations you must analyse is twenty factorial.

Calculating factorials is, on one hand, very straightforward. You simply multiply each factor, by all of the other factors, in turn. Thus, twenty factorial = 20 x 19 x 18 x 17 x 16 etc.

The result of multiplying 20 x 19 x 18 x 17 x 16 etc. is you end up with the following number: 432,902,008,176,640,000. Which is the number of different possible combinations between twenty factors. Rounding this figure up slightly, that equates to four hundred and thirty-three quadrillion. Which is a lot. And it gets far worse than that.

As far back as 1981, a paper was published outlining 246 different risk factors involved in CVD ¹. Today, there would be far more, several thousand at least. However, even by 1981 the number of possible combinations was already incomprehensibly huge. I say this because 246 factorial is:

980360372638941007038951797078339359751464353463061342202811188548638347461066010066193275864531994024640834549254693776854464608509281547718518965382728677985343589672835884994580815417004715718468026937051493675623385569404900262441027874255428340399091926993707625233667755768320823071062785275404107485450075779940944580451919726756974354635829128751944137276448671023801110260206915547825809239994946405007360000000000000000000000000000000000000000000000000000000000

Yes, to my amazement, there is a website which will calculate factorials for you. You don’t think I worked that out myself do you? I would have definitely got bored and made several mistakes on the way. Therefore, I have no idea if this figure is right or wrong, but it seems to be in the right sort of ballpark.

There is no way to even describe a number that big, and it would certainly make for some jigsaw puzzle. In truth what we have here represents a figure so huge that you cannot possibly do anything with it. It has fifty-seven zeros before you even get to another number. At least I think it is fifty-seven, I may have lost count.

How long would it take to feed in the data on all these risk factors, run the combinations, and see if you can establish how they all fit together? That would take as close to an infinite amount of time as makes no practicable difference. Even with the latest Google quantum computer.

Thinking about things in this way, I came to realise that unearthing risk factor, after risk factor, after risk factor, was not going to make it easier to work out the cause of CVD. It was making it impossible.

The other word for impossible, I came to realise, is ‘multifactorial’.

Multifactorial = a word commonly used by cardiologists to prevent any discussion as to the real causes of CVD. In conversation on this issue, I silently change the word multifactorial to ‘246-factorial’, just to remind myself what a stupid concept it is to call a disease multifactorial. Then to believe that, by doing so, you have explained anything. ‘So, how do the factors all fit together?’ I mutter, imaging a number so vast that it is beyond comprehension.

Then I may quote Poincaré at them.

‘Science is built up of facts, as a house is built of stones; but an accumulation of facts is no more a science than a heap of stones is a house.’ Henri Poincaré.

Because multifactorial also effectively = a pile of stones. Well done, you have found thousands of stones, and carefully piled them ever higher, but this gets no nearer to constructing a house. To build a house you need to know how all the stones join up. You need a plan my friend.

Which starts to bring me, in a roundabout way, back to lead.

As regular readers of this blog will know, I ripped up the multifactorial model of CVD and tried to replace it with a process model. The plan of the house, if you like. I was no longer interested in finding endless risk factors, then chucking them on the pile. I wanted to know the process – or processes – involved.

In the end I stripped it down to three main elements. Basement, walls, roof.

• Endothelial damage (damage to the lining of artery walls)
• Formation of a blood clot
• Repair

Or at least I stripped it down to three main processes – going wrong. Because this triad is all quite normal, and healthy. It is only when endothelial damage and clot formation accelerate, or repair is sub-optimal, that CVD/atherosclerosis will develop.

So, the simplest possible model is: rate of damage > rate of repair = CVD

Using the three-process model I began a different search. Starting with things that could damage the endothelium. I cast the net far and wide. Of course, it is more difficult to do the searching this way. Where do I begin? Do you just start thinking of things that might be damaging, and hope for the best? You will find yourself wandering all over the place. At least I did. Although it is quite an interesting journey – for a geek.

Bringing some structure into my search strategy, I decided that heavy metals were something that could not be doing any good to the human body. Mercury, lead, cadmium, and suchlike. Gold? Gold doesn’t seem to do much, one way or another. It was used to treat rheumatoid arthritis at one time. As for the others – not great. Lots of damage to health.

But do they damage the endothelial lining of the artery wall? Well, yes, they do. Looking at lead, here is a passage from the paper: ‘Mechanisms of lead-induced hypertension and cardiovascular disease.’

I admit that it is far too jargon heavy for most people. But I enjoyed it and I reproduced it in full because, what we have here, is the perfect storm. Many mechanisms I have previously mentioned in my long and winding series on what causes heart disease can be found here. Including many I did not mention because they were just too technical. I have put in bold some of the more important mechanisms:

‘Lead is a ubiquitous environmental toxin that is capable of causing numerous acute and chronic illnesses. Population studies have demonstrated a link between lead exposure and subsequent development of hypertension (HTN) and cardiovascular disease. In vivo and in vitro studies have shown that chronic lead exposure causes HTN and cardiovascular disease by promoting oxidative stress, limiting nitric oxide availability, impairing nitric oxide signaling, augmenting adrenergic activity, increasing endothelin production, altering the renin-angiotensin system, raising vasoconstrictor prostaglandins, lowering vasodilator prostaglandins, promoting inflammation, disturbing vascular smooth muscle Ca2+ signaling, diminishing endothelium-dependent vasorelaxation, and modifying the vascular response to vasoactive agonists. Moreover, lead has been shown to cause endothelial injury, impede endothelial repair, inhibit angiogenesis, reduce endothelial cell growth, suppress proteoglycan production, stimulate vascular smooth muscle cell proliferation and phenotypic transformation, reduce tissue plasminogen activator, and raise plasminogen activator inhibitor-1 production.’ ²

So, there you go. Not just one mechanism of action, but twenty-one different processes that lead can cause CVD. Fifteen ways of damaging the endothelium, four that inhibit repair, and two mechanisms for making blood clots more difficult to get rid of, as highlighted in the final passage… reduce tissue plasminogen activator, and raise plasminogen activator inhibitor-1 production.’

Tissue plasminogen activator (TPa) is the enzyme that activates the breakdown of blood clots. TPa converts plasminogen to plasmin, and plasmin then chops fibrin to bits, thus shaving down blood clots. Plasminogen activator inhibitor-1 is a substance that inhibits the action of tissue plasminogen activator (TPa = the clot buster, often given to patients after a heart attack or stroke).

Clearly, if you reduce TPa, and increase TPa inhibition, you end up with a blood clot that is very difficult to get rid of and is thus more damaging.

So, when people ask, have you got a mechanism of action to explain how lead causes CVD I say (rather smugly), no, I have got twenty-one. In truth, I have found quite a few more, but twenty-one is probably enough to be getting on with. One thing I have found is that once you start looking at all the potential processes, there seems almost no end to this stuff. It stretches in all directions.

Big fleas have little fleas upon their backs to bite ’em,

And little fleas have lesser fleas, and so, ad infinitum.

And the great fleas, themselves, in turn, have greater fleas to go on;

While these again have greater still, and greater still, and so on

Anyway, getting back on track, I started to look for factors, causal agents, whatever is the best name for them, that can impact on one of three processes:

• Endothelial damage (damage to the lining of artery walls)
• Formation of a blood clot
• Repair

This is how I got to lead, only to discover that there was a huge body of research linking lead to CVD… that I had been completely unaware of. My analogy was that of a round the world sailor bumping into Australia and wondering why no-one had bothered to tell him it was there. ‘It’s pretty big, you know.’

Looking at things, by starting with one of the three processes, is also how I came across the evidence on sickle cell disease (SCD). I reasoned that sharp pointy red blood cells (sickled cells) hammering through the blood vessels would create serious damage to endothelial cells.

When I started looking, I found that, in some studies, SCD increases the (relative risk) of CVD by fifty thousand per cent. Yes, you did read that right. Fifty thousand per cent. With none of the other ‘established’ risk factors present.

Which makes SCD a ‘sufficient’ cause of CVD. In fact, it is the only sufficient cause I have ever found – in that it can lead to atherosclerosis in the blood vessels in the lungs, where the blood pressure is pretty low.

Which means that, with SCD, you don’t even need a high blood pressure. SCD can cause CVD all by itself. If you can find any other factor that can do that – let me know. For a more in-depth discussion on causation, and the concept of ‘sufficient’ see this article: https://jech.bmj.com/content/55/12/905.long

Then, I thought, what else causes damage to the endothelium. I ended up looking at a group of diseases known as ‘vasculitis’. Itis means, inflammation, as in tonsillitis, appendicitis. So, vasculitis means inflammation of the vascular system, by which I mean inflammation of the lining of the blood vessels. By which I mean, damage (and repair) to the lining of the blood vessels. Remember, inflammation = repair.

There are many different forms of vasculitis, most of which are not really thought of as being ‘vasculitis.’ For example, Rheumatoid arthritis, and Systemic Lupus Erythematosus. These conditions cause inflammation in many different places, but they also cause vasculitis. You may have noticed that both also appear on the Qrisk3 calculator.

Other forms of vasculitis, or diseases where vasculitis is an important part of the spectrum of abnormalities include:

• Scleroderma
• Sjogren’s
• Erythema nodosum
• Takayasu’s arteritis
• Kawasaki’s disease

I think they all have great, evocative names:

All these forms of vasculitis are associated with a greatly increased risk of CVD. You can look this up yourself, if you want. In fact, children who suffer Kawasaki’s can die of myocardial infarctions (MIs), aged five. They have a brief, super-accelerated, form of endothelial damage that lasts a few weeks. Some can then end up with large aneurysms (balloon-like swellings) in their coronary arteries. These can burst, causing a MI.

So, not an entirely conventional MI. Nor conventional atherosclerosis. However, if you think of an aneurysm as a late stage abnormality in atherosclerosis [which most are] then in Kawasaki’s we can get from endothelial damage, to an aneurysm, in a month. Something that normally takes about sixty years to develop.

Three stones to make a wall

Lead, sickle cell disease, vasculitis.

In one sense it could be said that I have been discussing three completely unrelated things here. Lead, sickle cell disease, vasculitis. In another sense I hope you can see that these three ‘factors’ are related to CVD. Not by what they are, but by what they do. The damage they cause… the process.

They all fit very neatly into the walls of the house that are called ‘endothelial damage’. How else can you explain how three such disparate things can possibly cause exactly the same disease.

I must admit that this breakthrough in my thinking, from causes to process, was not mine. It was entirely due to one man. Professor Paul Rosch. We were discussing stress (strain) and CVD and he was critiquing a presentation I had given.

I shall paraphrase his comment. ‘Very good, you have given us the what, but not the how.’ Yes, very simple, when you think of it that way. What he was really asking was, what is the process? Since then, I have often wondered why have others not gone down this route?

I then realised that the problem, the great problem in all research into CVD, is that very early on it was decreed that LDL/cholesterol causes CVD. Therefore, all thinking, and any hypothesis on CVD required that LDL sat at the centre.

To my mind this is like opening a two-thousand-piece jigsaw puzzle and deciding, straight away, that one big piece – LDL/cholesterol – sits at the centre, and the other pieces must be made to fit around it.

Well, perhaps it does have a (small role) to play in CVD, but it most certainly does not sit and the centre. But if you keep it there, you distort the entire puzzle and make it impossible to complete. The pieces must be forced into place. Hammered down, or twisted into extreme shapes.

This, though, is where CVD research currently sits. Thousands of pieces are lying about the board. A few of them have been fitted together, here and there. As for the whole puzzle, it is doomed to failure, because the wrong piece is taking up the key position. Unfortunately, if you are a ‘serious’ CVD researcher, who wants to get grants for research, you can’t move it.

What I found if that you chuck that piece away, and start again, then everything becomes clear. The puzzle can be made to fit into one of these three processes:

• Endothelial damage (damage to the lining of artery walls)
• Formation of a blood clot
• Repair

Lead, for example. Lead makes no sense as a significant risk factor using conventional thinking. It doesn’t raise BP, it doesn’t raise LDL, it doesn’t cause diabetes, it simply does not fit. So, it has become, essentially, ignored. But how can you ignore something that may be responsible for four hundred thousand deaths per year, in the US alone? Most of them CVD deaths?

The answer is that you cannot.

1: https://www.atherosclerosis-journal.com/article/0021-9150(81)90122-2/abstract

2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2519216/

23 September 2019

Lead again

I am returning to lead, the heavy metal. Not the verb to lead, or a noun – such as a dog lead. Yes, English is complicated, with the same word meaning several different things, which can lead to confusion.

I am indebted to Leon Vd Berg for bringing my attention to another paper about lead that I had missed. Which is slightly surprising as I tend to look for such papers. However, such is the daily avalanche of medical publications that it is literally, impossible to keep up.

There are several things about the paper that I found fascinating. However, the first thing that I noticed was that…. it hadn’t been noticed. It slipped by in a virtual media blackout. It was published in 2018, and I heard nothing.

This is in direct contrast to almost anything published about diet. We are literally bombarded with stories about red meat causing cancer and sausages causing cancer and heart disease, and veganism being protective against heart disease and cancer, and on and on. Dietary articles often end up on the front page on national newspapers.

Here is one such headline from the Daily Mail 7^th August 2019

‘Eating chicken instead of steak, lamb or sausages ‘slashes a woman’s risk of developing breast cancer by 28%’

Mind you, here is another headline from the Daily Mail 8^th Sept 2019

‘Chicken ’causes cancer’: Oxford University scientists say people who eat poultry are at increased risk of developing deadly disease.’

Tricky thing eating chicken. It can cause and prevent cancer simultaneously. You read it here first.

However, the point I wish to make is not so much the utter nonsense and constant contradictions of dietary studies. Nor is it the fact that the increased, and decreased risk in such studies, is minute. Sitting well within the boundaries of reasonable chance. Which is why you keep getting contradictory studies.

Researcher one:      ‘I just threw a head – all throws of a coin must be heads.’

Researcher two:       ‘No, sorry, I just threw two tails – most throws of a coin end up tails

Researcher one:      ‘Hold on, forget your tails, I just go four more heads – in a row – most throws end up heads, not tails.’

The correct term for this is idiot research, and those who do it are – primarily – idiots. However, none of this nonsense is really important. The point I am trying to make here is that this type of dietary research hogs the limelight.

It seems that whatever else Ancel Keys did not achieve – scientific truth and accuracy, for starters – he most certainly did manage to convince almost everyone in the World that diet is the single most critical important factor for health.

In years gone by, people ate food because they enjoyed eating it. This still happens in France. Imagine that. Nowadays every meal comes with implied fearmongering, and high-level criticism. Are you destroying the world or not – you evil scum.

‘Hold on, it’s only a bacon sandwich. With a fried egg and a bit of cheese grated on top…. Yes, I suppose you’re right, I am personally responsible for the destruction of the Amazonian rain forest. Forgive me father, for I have sinned.’

Destruction of the planet is only one aspect of eating, it’s also destruction of your health – with added moral judgement. If you go to Slimming World, you can eat various tasteless stuff, but you are allowed ‘sins.’ A sin would be something you really like eating, but it is so deadly, that it is a sin to eat it. Chocolate, for example. Get thee behind me Satan.

I don’t understand how anyone manages to eat anything nowadays. I have almost given up eating salads because someone will always remark ‘Oooooh, that’s healthy.’

My reply used to be. ‘I am not eating it because it is healthy, I am eating it, because I enjoy it.’ Nowadays I just grunt in a vaguely non-threatening way. I do not say. ‘No, a healthy meal would be a full English breakfast with bacon, eggs, sausages, fried bread. a few more sausages and a bit of lard melted on top.’

I do not say this because, in truth, almost all diets are perfectly healthy. Vegetarian, paleo, keto, vegan (with a few essentially nutrients thrown in, so you don’t die), HFLC, etc. In fact, the only non-healthy diet would be the one recommended by all the experts around the world.

Namely, High carb, low fat (HCLF). The ‘eat well plate’, ‘the food pyramid’ – whatever it is now called. Stay away from that, and you will be fine.

Rule one of diet.       Everything the ‘experts’ recommend, is wrong.

Rule two:                   Eat food you enjoy – and enjoy eating

Rule three:                Eat food that looks like food

Rule four:                   Cook your own meals – when possible

Rule five:                   Try fasting from time to time

Rule six:                     That’s it

Where was I? Oh yes, lead. The heavy metal. The thing that, unlike diet, makes no headlines whatsoever, the thing that everyone ignores. Here is one top-line fact from that study on lead, that I missed:

‘Our findings suggest that, of 2·3 million deaths every year in the USA, about 400 000 are attributable to lead exposure, an estimate that is about ten times larger than the current one.’ ¹

Yes, according to this study, one in six deaths is due to lead exposure. I shall repeat that. One in six. Eighteen per cent to be exact, which is nearer a fifth really.

Of course, this study is observational, with all the usual caveats associated with such studies. Indeed, many people commenting on this blog have stated that correlation [found in such studies] does not mean causation. I think you will find that this does not include me – although I may have said it by mistake. It is true that correlation does not mean causation, up to a point. However, once that point has been reached, causation can be considered proven.

For example, in observational studies, smokers were found to have fifteen times the risk of lung cancer. That is a powerful enough correlation to prove causation – beyond any reasonable doubt. There is no point in setting up a controlled clinical trial to prove this. In fact, any such trial would be completely unethical.

The question is, at what level of increased risk/correlation can causality be accepted. There is no absolute clear-cut answer to this Life ain’t black and white. However, most epidemiologists will tell you that unless the odds ratio (OR) is above two, you cannot attempt to claim causality. Too much noise, too many possible confounders.

Which means (deep breath, waiting for statisticians to attack this mercilessly) you need to find that a ‘factor’ is associated with at least a doubling of risk, before you do not simply crumple up the published paper and throw it in the bin.

Most dietary studies get absolutely nowhere near two. We have risks such as one point one (1.10), or one point three. One point three (1.3) is a thirty per-cent increase in risk. Here for instance is a review of red meat and colo-rectal cancer

‘As a summary, it seems that red and processed meats significantly but moderately increase CRC risk by 20-30% according to these meta-analyses.’  ²

Figures like this, from an observational study, mean only one thing. Crumple, throw, bin. Remember also, they are only looking at one form of disease colo-rectal cancer (CRC).  The impact on overall mortality (the risk of dying of anything) would be minuscule, if it could even be found to exist at all. Of course, overall mortality is not mentioned in that CRC paper. Negative findings never are.

So, on one side, we have papers (that make headlines around the world) shouting about the risk of red meat and cancer. Yet the association is observational, tiny, and would almost certainly disappear in a randomised controlled trial, and thus mean nothing.

On the other we have a substance that could be responsible for one sixth of all deaths, the vast majority of those CVD deaths. The odds ratio, highest vs lowest lead exposure, by the way, depending on age and other factors, was a maximum of 5.30 [unadjusted].

Another study in the US found the following

‘Cumulative lead exposure, as reflected by bone lead, and cardiovascular events have been studied in the Veterans’ Normative Aging Study, a longitudinal study among community-based male veterans in the greater Boston area enrolled in 1963. Patients had a single measurement of tibial and patellar bone lead between 1991 and 1999. The HR for ischemic heart disease mortality comparing patellar lead >35 to <22 μg/g was 8.37 (95% CI: 1.29 to 54.4).’ ³

HR = Hazard Ratio, which is similar, if not the same to OR = Odds Ratio. A Hazard Ratio of 8.37, means (essentially) a 737% increase in risk (Relative Risk).

Anyway, I shall repeat that finding a bit more loudly. A higher level of lead in the body leads to a seven hundred and thirty-seven per cent increase in death from heart disease. This is, in my opinion, correlation proving causation.

Looking at this from another angle, it is true that smoking causes a much greater risk of lung cancer (and a lesser but significant increase in CVD), but not everyone smokes. Therefore, the overall damage to health from smoking is far less than the damage caused by lead toxicity.

Yet no-one seems remotely interested. Which is, in itself, very interesting.

It is true that most Governments have made efforts to reduce lead exposure. Levels of lead in the children dropped five-fold between the mid-sixties and the late nineties. ⁴ Indeed, once the oil industry stopped blowing six hundred thousand tons of lead into the atmosphere from vehicle exhausts things further improved. Lead has also been removed from water pipes, paint, and suchlike.

However, it takes a long old time from lead to be removed from the human body. It usually lingers for a lifetime. Equally, trying to get rid of lead is not easy, that’s for sure. Having said this, chelation therapy has been tried, and does seem to work.

‘On November 4, 2012, the TACT (Trial to Assess Chelation Therapy) investigators reported publicly the first large, randomized, placebo-controlled trial evidence that edetate disodium (disodium ethylenediaminetetraacetic acid) chelation therapy significantly reduced cardiac events in stable post–myocardial infarction (MI) patients. These results were so unexpected that many in the cardiology community greeted the report initially with either skepticism (it is probably wrong) or outright disbelief (it is definitely wrong).’ ³

Cardiologists, it seems from the above quotes, know almost nothing about the subject in which they claim to be experts. Just try mentioning glycocalyx to them… ‘the what?’

Apart from a few brave souls battling to remove lead from the body, widely derided and dismissed by the mainstream world of cardiology, nothing else is done. Nothing at all. We spend trillions on cholesterol lowering, and trillions on blood pressure lowering, and more trillions on diet. On the other hand, we do nothing active to try and change a risk factor that kicks all the others – in terms of numbers killed – into touch.

Funny old world. Is it not?

Next time, back to diet, because everyone knows how important diet is…. Only joking.

1: https://www.thelancet.com/journals/lanpub/article/PIIS2468-2667(18)30025-2/fulltext

2: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4698595/

3: https://www.sciencedirect.com/science/article/pii/S0735109716015989

4: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240871/pdf/ehp0110-000563.pdf

19th January 2019

I suppose it is gratifying to see things I write very strongly supported a few days later. After telling everyone that a high cholesterol level is not a risk for stroke, out comes a study almost straight away, demonstrating that a low cholesterol level increases mortality in patients who have already had a stroke.

This was in a population – and I would highlight this fact – in a population who have high grade carotid artery stenosis. Which mean a high degree of atherosclerosis on the carotid arteries (supplying blood to the brain). The paper is called:

‘Lower cholesterol tied to increased mortality in ischaemic stroke patients with carotid artery stenosis.’

Takeaway

In patients with acute, first-ever ischaemic stroke with high-grade internal carotid artery (ICA) stenosis and post-stroke functional dependence, lower total cholesterol level was associated with increased risk for 5-year mortality.

Why this matters:

Recent treatment guidelines of hyperlipidaemia suggest more aggressive treatment for reducing risk for atherosclerotic cardiovascular diseases and ischaemic stroke.

However, these findings suggest a careful consideration of aggressive treatment of hyperlipidaemia in patients with acute, first-ever ischaemic stroke with high-grade ICA stenosis and post-stroke functional dependence.

Study design:

Study prospectively evaluated 196 patients with acute ischaemic stroke with high-grade ICA stenosis and modified Rankin Scale score ≥3.

Patients were divided into 2 groups based on total cholesterol level at admission: ≥200 or <200 mg/dL.

Patients were followed-up for 5 years after initial assessment.

Key results:

After adjusting for established clinical predictors of adverse outcomes, lower total cholesterol level (aHR, 1.88; 95% CI, 1.09-3.23; P=.023) was a significant risk factor for 5-year all-cause mortality.

The prevalence of diabetes mellitus (P=.013) was significantly higher and that of atrial fibrillation (P=.011) was significantly lower in patients with high vs low total cholesterol level.

Patients with lower cholesterol level had significantly lower value of haemoglobin (P=.001), whereas glycohaemoglobin was significantly higher in patients with higher total cholesterol level (P=.001).

Funding: None.

Four most annoying words in the English language. ‘I told you so.’

Of course, this study will be dismissed out of hand. “We should still be prescribing statins to people who have had ischaemic strokes” we will be told. “Studies like this are purely observational” we will be told. “A high cholesterol level still needs to be lowered” we will be told. Nothing to see here, please move along!

I do become increasingly weary of finding evidence that directly and absolutely contradicts the cholesterol hypothesis. It never makes the slightest difference – to anything. Hopefully a few people are out there listening, whose minds are not made of reinforced concrete.

1: https://www.univadis.co.uk/viewarticle/lower-cholesterol-tied-to-increased-mortality-in-ischaemic-stroke-patients-with-carotid-artery-stenosis-651463

Lung YJ, Weng WC, Wu CL, Huang WY. Association Between Total Cholesterol and 5 year Mortality in Patients with Carotid Artery Stenosis and Poststroke Functional D ependence. J Stroke Cerebrovasc Dis. 2019 Jan 11 [Epub ahead of print]. doi: 10.1016/j.jstrokecerebrovasdis.2018.12.030. PMID: 30642665

15th January 2019

In this never-ending story on heart disease, I have tended to use the terms “heart disease” and “cardiovascular disease” almost interchangeably. Well, everyone else does it, so why not me? However, in this blog I shall be splitting cardiovascular disease into its two main components, heart attacks and strokes, and concentrating mainly on strokes.

The first thing to say is that there are three main causes of strokes.

• Atrial Fibrillation (ischaemic)
• A burst blood vessel in the brain (haemorrhagic)
• A blood clot (ischaemic)

[There are also cryptogenic strokes (no known cause), strokes due to a hole in the heart, strokes due to antiphospholipid syndrome, strokes due to sickle cell disease etc. etc.)

Atrial Fibrillation (AF) is a condition where the upper chambers of the heart (atria) do not contract and relax smoothly every second or so. Primarily because there is a disruption in the electrical conduction system, causing the atria to spasm and twitch in a highly irregular fashion.

When this happens, blood clots can form in the left atrium then break off and head up into the brain and get stuck. Causing a stroke. They can also travel elsewhere in the body causing a blockage to an artery in the kidneys, the leg, the arm and suchlike. If they form in the right atrium, they will end up stuck in the lungs.

These clots are usually quite small, about the size of a large grain of rice, but this is still big enough to do quite considerable damage. The treatment for AF is either to try and reverse the fibrillation or, if this does not work, to give anticoagulants such as warfarin to stop the clots forming.

A haemorrhagic stroke is when a blood vessel in the brain bursts. Blood is then forced into the brain and causes a lot of damage – leading to a stroke. Haemorrhagic strokes are usually quite severe, as you can imagine. The treatment is to NOT give an anti-coagulant of any sort. Haemorrhagic strokes are often/usually caused by a thinning of the artery wall, causing a ballooned area (aneurysm), which then bursts.

An interesting question, and I have seen different views on this is whether a small blood clot travels to the brain where it gets stuck, but does not completely block the artery, so it does not cause a stroke, but it creates an area of damage – which is then repaired – that leaves a weakness in the artery that balloons out – an aneurysm.

Anyway, the most common cause of a stroke is that large atherosclerotic plaques form in the main arteries that supply blood to the brain (carotid arteries). These plaques usually form around the base of the neck. A blood clot then forms on top of the plaque, then breaks off and travels to the brain, where it gets stuck – as with atrial fibrillation – causing a stroke. The effect is the same as with AF, but the underlying causing is completely different.

According to the American Stroke Association 87% of strokes are ischaemic.

Which means that the vast majority of strokes are caused by atherosclerotic plaques in the neck. Just as the vast majority of heart attacks are caused by atherosclerotic plaques in the coronary arteries. Therefore, you would expect that the risk factors for stroke would be exactly the same as the risk factors for heart attacks, as the underlying process is the same.

Well, many of the standard risk factors are the same. Smoking, diabetes, high blood pressure and suchlike. However, a raised LDL most certainly is not. There is a research study called the Simon Broome registry, started in the UK, that tracks the health outcomes of people diagnosed with familial hypercholesterolaemia (FH).

It is a fascinating resource which, if you decide to interpret their data through a different prism, virtually rules out the raised LDL in familial hypercholesterolaemia as a cause of CVD. One of the earlier papers in the BMJ, on the findings of the Simon Broome registry, found that:

‘Familial hypercholesterolaemia is associated with a substantial excess mortality from coronary heart disease in young adults but may not be associated with a substantial excess mortality in older patients.’¹

For ‘may not be’, replace, ‘is not’. In fact, what the Simon Broome registry has found repeatedly is that, after the age of, about fifty, FH does not increase the risk of coronary heart. Thus LDL is a risk factor before the age of fifty, and not after? Which means that it cannot be a risk factor at all [the thing that kills young people with FH before the age of fifty is clotting factor abnormalities – not raised LDL]

Which is something covered in the magnificent and insightful paper: ‘Inborn coagulation factors are more important cardiovascular risk factors than high LDL-cholesterol in familial hypercholesterolemia.’² Yes, as you may have guessed, I was a co-author.

However, if we move away from heart disease, to strokes. FH has never been found to be a risk factor for stroke – at any age. Here, for example is a study done in Norway, and published in the Journal Stroke. It was called ‘Risk of ischaemic stroke and total cerebrovascular disease in familial hypercholesterolaemia.’

A total of 46 cases (19 women and 27 men) of cerebrovascular disease were observed in the cohort of people with FH, with no increased risk of cerebrovascular disease compared with the general population (standardized incidence ratio, 1.0; 95% CI, 0.8–1.4). Total number of ischemic strokes in the cohort of people with FH was 26 (9 women and 17 men), with no increased risk compared with the general population (standardized incidence ratio, 1.0; 95% CI, 0.7–1.5).³

In 2010 the Lancet published a major study looking at risk factor for stroke in the non-FH population³. They used the term population attributable risk factors (PAF), which ‘weights’ the factors, depending on how prevalent they are (i.e., how many people have got the various risk factors). Their list of PARs for stroke was as follows:

• 51.8% – Hypertension (self-reported history of hypertension or blood pressure >160/90mmHg)
• 18.9% – Smoking status
• 26.5% – Waist-to-hip ratio
• 18.8% – Diet risk score
• 28.5% – Regular physical activity
• 5% – Diabetes mellitus
• 3.8% – Alcohol intake
• 4.6% – Psychosocial stress
• 5.2% – Depression
• 6.7% – Cardiac causes (atrial fibrillation, previous MI, rheumatic valve disease, prosthetic heart valve)
• 24.9% – Ratio of ApoB to ApoA (reflecting cholesterol levels)

You will see that LDL is not in that list. The ratio of ApoB to ApoA is. However, this is primarily the ratio of VLDL (triglycerides) to HDL (‘good’ cholesterol), which is an accurate reflection of ‘insulin resistance’ and bears no relationship to LDL. As I always say to people who ask me for advice on reviewing clinical research…’the most important thing to focus on is not what is there, it is what is not there.’

Any study on CVD will be examining LDL levels very closely. If a relationship were found it would be shouted from the rooftops. The fact that you hear nothing about LDL in this paper means that there was no correlation – at all.

You can, if you wish, try to find some evidence that the risk of stroke is increased by a raised LDL level. I must warn you that you will look for a long time, because there is no evidence, anywhere – at all. It has interested me for many years that this issue is simply swept under the carpet.

Now, write out one hundred times:

• Raised LDL is not a risk factor for stroke
• Raised LDL is not a risk factor for stroke
• Raised LDL is not a risk factor for stroke….

Then, ask yourself the question. How can a raised LDL be a risk factor for heart disease and not stroke – as the two conditions are, essentially, the same condition? Atherosclerotic plaques in medium sized arteries with the critical/final event being the formation of a blood clot – on top of the plaque.

Then, ask yourself another question. If a raised LDL is not a risk factor for stroke, how can lowering the LDL level provide any benefit? The correct answer is that… it cannot. Yet statins do provide benefit in stroke (Usual proviso here. Not by a great amount in absolute terms, but the benefit does appear to exist).

‘A meta-analysis of randomized trials of statins in combination with other preventive strategies, involving 165,792 individuals, showed that each 1-mmol/l (39 mg/dl) decrease in LDL-cholesterol equates to a reduction in relative risk for stroke of 21.1 (95% CI: 6.3-33.5; p = 0.009)’ ⁴

Just to repeat the main point here. A raised LDL is not, and has never been, a risk factor for stroke. Yet it is claimed that lowering the LDL level reduces the risk of stroke? In reality, the evidence from the statin trials prove, beyond any doubt, that any benefit achieved by statins cannot be through lowering the LDL level.

The logic stripped down is, as follows:

• A raised level of factor A does not cause disease B
• Thus lowering factor A cannot reduce the risk of disease B
• Thus, you cannot claim that lowering factor A can have any possible effect on disease B

However, every single cardiovascular expert seems delighted to inform us, in all seriousness, that lowering factor A does, indeed, reduce the risk of disease B. Despite this breaking the very fabric of logic in two.

“Alice laughed: “There’s no use trying,” she said; “one can’t believe impossible things.”

“I daresay you haven’t had much practice,” said the Queen. “When I was younger, I always did it for half an hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast.” Alice in Wonderland.

1: https://www.bmj.com/content/303/6807/893

2: https://www.ncbi.nlm.nih.gov/pubmed/30396495

3: https://www.ahajournals.org/doi/10.1161/STROKEAHA.118.023456

4: https://www.ncbi.nlm.nih.gov/pubmed/19814666

2 January 2019

‘It is difficult to make predictions, particularly about the future.’ Old Danish proverb

The hallmark of a great scientific hypothesis is prediction. Einstein’s theory of special relativity predicted that gravitational fields could be demonstrated to bend light – and he was proven right during observations made during a total eclipse of the sun.

Unfortunately, things are rarely as black and white as that. Even if you understand almost all of the factors at play, it can be extremely difficult to predict certain events, particularly the timing. Earthquakes, hurricanes, which flu virus will be active next year? There are so many variables interacting with each other that things get very complex. When will San Francisco suffer the next major earthquake? According to the best predictions – about twenty years ago.

Chaos theory can also play its part. A very small change in one part of a system can trigger massive downstream effects. A butterfly flaps its wings in Africa, and two weeks later a hurricane devastates Florida.

So, what of predicting your future risk of cardiovascular disease? How good are the current models? Are they of any use at all?

In the US, the calculator that is most widely used was put together by the American Heart Association and American College of Cardiology.(AHA/ACC). It is called the ‘cvriskcalculator’ It can be found on-line here http://www.cvriskcalculator.com/ It asks you to provide data on ten different parameters:

• Age
• Sex
• Race
• Total cholesterol
• HDL (good) cholesterol
• Systolic blood pressure
• Diastolic blood pressure
• Treated for blood pressure: yes or no
• Diabetes: yes or no
• Smoker: yes or no

After you input your data, an algorithm kicks into action to work out your cardiovascular future. If it calculates that your risk of suffering a CV event is greater than 7.5%, within the next ten years, you will be recommended to start on a statin. This, you will have to take for the rest of your life.

One word of warning, all men by age of fifty-five – even men with no other risk factors at all – will have a risk greater than 7.5%. At least they will, using ‘cvrisk’. Because age is by far the most powerful risk factor of all – at least it is on ‘cvrisk’.

In the UK, a more complex risk factor calculator has been developed. In truth, it is only more complex in that it has an additional ten risk factors to consider. It is called Qrisk3. It uses twenty different factors to calculate risk https://qrisk.org/three/:   They are, in no particular order:

• Age
• Sex
• Smoking
• Diabetes
• Total cholesterol/HDL ratio
• Raised blood pressure
• Variation in two blood pressure readings
• BMI
• Chronic kidney disease
• Rheumatoid arthritis
• Systemic Lupus Erythematosus (SLE)
• History of migraines
• Severe mental illness
• On atypical antipsychotic medication
• Using steroid tablets
• Atrial fibrillation
• Diagnosis of erectile dysfunction
• Angina, or heart attack in first degree relative under the age of 60
• Ethnicity
• Postcode

How good are they at predicting a future event? A study was carried out in the US to analyse, in retrospect, how accurate the cvriskcalculator had been. They looked at the historical risk scores of several thousand people, then tracked forward in time to see what actually happened.

In the study they looked at CVD over five years, not ten, so all figures should be doubled to establish the ten-year risk that is used in most calculators:

‘A widely recommended risk calculator for predicting a person’s chance of experiencing a cardiovascular disease event — such as heart attack, ischemic stroke or dying from coronary artery disease — has been found to substantially overestimate the actual five-year risk in adults overall and across all sociodemographic subgroups. The study by Kaiser Permanente was published today in the Journal of the American College of Cardiology.

The actual incidence of atherosclerotic cardiovascular disease events over five years was substantially lower than the predicted risk in each category of the ACC/AHA Pooled Cohort equation:

For predicted risk less than 2.5 percent, actual incidence was 0.2 percent

For predicted risk between 2.5 and 3.74 percent, actual incidence was 0.65 percent

For predicted risk between 3.75 and 4.99 percent, actual incidence was 0.9 percent

For predicted risk equal to or greater than 5 percent, actual incidence was 1.85 percent

“From a relative standpoint, the overestimation is approximately five- to six-fold,” explained Dr. Go” ¹

What this means is that you carefully input your parameters into a risk calculator, which took many years of painstaking work to develop, using data carefully gathered by experts from the world of cardiology, and it overestimates your risk by five to six-fold. (I.e., 400 – 500% exaggeration!)

Excellent. Just for starters, this means that millions upon millions of people have been told to take a statin based on a calculation that is so wildly inaccurate as to be virtually meaningless. How so, Dr Go?

On a similar note, a group of researchers in the UK decided to look at data gathered on 378,256 patients from UK general practices. They wanted to establish which factors were most important in predicting future risk. The paper was called ‘Can machine-learning improve cardiovascular risk prediction using routine clinical data?’ ²

If the ACC/AHA and Qrisk3 calculators truly are looking at the most important variables, then we should see all the same factors appearing in this UK study. Below, just to remind you, are the ten factors used in the ACC/AHA calculator:

• Age
• Sex
• Race
• Total cholesterol
• HDL (good) cholesterol
• Systolic blood pressure
• Diastolic blood pressure
• Treated for blood pressure: yes or no
• Diabetes: yes or no
• Smoker: yes or no

Here is what the UK researchers found to be the top ten risk factors for CVD, in order, with number one being highest risk and number ten lowest risk:

1. Chronic Obstructive Pulmonary Disease (usually a result of smoking)
2. Oral corticosteroid prescribed
3. Age
4. Severe mental illness
5. Ethnicity South Asian
6. Immunosuppressant prescribed
7. Socio-economic-status quintile 3
8. Socio-economic status quintile 4
9. Chronic Kidney Disease
10. Socio-economic status quintile 2

Compare and contrast, as they say. Do these lists look remotely the same? As you can see, there are only two factors on the ACC/AHA list that were replicated by the UK researchers. One of them is age – which you can do nothing about, and the other is ethnicity – which you can do nothing about. As for the rest. Where have they gone?

What of cholesterol, and sex, and blood pressure, and smoking, and diabetes. Well, out of a total of forty-eight factors analysed, here is where they ranked in importance. In this analysis factors could either be ranked protective, or causal:

Smoking                                  = 18

Sex/female                              = 19 (protective)

Total cholesterol                    = 25

HDL cholesterol                      = 28 (protective)

Systolic blood pressure          = 29

Diabetes                                  = 31

LDL ‘bad’ cholesterol              = 46

Yes, LDL ranked 46th out of 48 factors, well, well, who’d a thunk. The only things that scored lower than LDL were FEV1 and AST/ALT ratio. Factors that, unless you are medically trained, you will never have heard of. The first one, FEV1 stands for forced expiratory volume (from your lungs), measured over one second. The other is the ratio of two liver enzymes.

At present, it is true to say that the established risk factors, and the risk calculators, are almost completely useless. Not only that, they get more useless if you try to use them across different countries. If I took Qrisk3, or ‘cvrisk’ to France, whatever risk it calculated, I would then have to divide whatever figure I got, by four.

This is because, for exactly the same set of risk factors, someone in France will have one quarter the rate of CVD as a man in the US, or UK. Which means that the ‘cvrisk’ would actually overestimate risk by twenty-fold in France. Five times too high a calculated risk in the US, multiplied by four times too high a calculated risk in France. 5 x 4 = 20.

So, what should you measure? What can help you to predict your risk of CVD? Coronary calcium score (CAC)? That is, looking at the amount of calcium in your arteries. This is probably the most accurate way to establish your burden of atherosclerosis.

However, a high(er) CAC score does not mean that you are at risk of CVD, it means you have already got CVD, it is already there. The CAC score is just telling you how far along the CVD path you have traveled. So, it is not really predictive, it is more of a historical record.

What you really want is to stop the calcium forming in your arteries in the first place. Or then again, do you? A ‘calcified’ plaque is not, necessarily, a dangerous plaque. A dangerous plaque has an almost liquid core, which is in danger of rupturing. A dangerous plaque is often called a vulnerable plaque, and they don’t show up well, if at all, on a CAC scan.

If you have lots of vulnerable plaque what should you do?

Take a statin. Statins accelerate calcification.

Take warfarin. Warfarin accelerates calcification

Both reduce the risk of dying of CVD – if only by a small amount (at least small with statins). So, you could both increase calcification and reduce your risk of a CV event – simultaneously. What then to make of your CAC score? If you find it is zero, great. If you find it is four hundred?

Logically, a high score only tells you that you have CVD, and already having CVD means you are at higher risk of dying of a CV event. Which comes as no great surprise. What you really need to be able to do is to accurately predict what your CAC score would be – before you did it. And if you could do that, you really would have a scientific hypothesis worthy of the name.

The LDL hypothesis for example. If you could find you someone with an extremely high LDL level, say four to five times average, and a CAC score of zero – at the age of seventy-two then you would remove it as a factor for prediction.

So, here you go – I have blogged about this before – from a paper called: ‘A 72-Year-Old Patient with Longstanding, Untreated Familial Hypercholesterolemia but no Coronary Artery Calcification: A Case Report.’

The subject has a longstanding history of hypercholesterolemia. He was initially diagnosed while in his first or second year as a college student after presenting with corneal arcus and LDL-C levels above 300 mg/dL [7.7mmol/l] ³

He reports that pharmacologic therapy with statins was largely ineffective at reducing his LDL-C levels, with the majority of lab results reporting results above 300 mg/dL and a single lowest value of 260 mg/dL while on combination atorvastatin and niacin. In addition to FH-directed therapy, our subject reports occasionally using baby aspirin (81 mg) and over-the-counter Vitamin D supplements and multivitamins.

In the early 1990s, our patient underwent electron beam computed tomography (EBCT) imaging for CAC following a series of elevated lipid panels. Presence of CAC (coronary artery calcification) was assessed in the left main, left anterior descending, left circumflex, and right coronary arteries and scored using the Agatston score.

His initial score was 0.0, implying a greater than 95% chance of absence of coronary artery disease. Because of this surprising finding, he subsequently undertook four additional EBCT tests from 2006 to 2014 resulting in Agatston scores of 1.6, 2.1, 0.0, and 0.0, suggesting a nearly complete absence of any coronary artery calcification. In February of 2018, he underwent multi-slice CT which revealed a complete absence of coronary artery calcification.

Prediction, prediction. The risk factor calculators cannot do it. LDL levels don’t do it. I cannot do it with perfect accuracy either. I cannot say to anyone that you will not die of CVD. I cannot say to anyone that you will die of CVD. I can only help you to change the odds.

If you are an elderly, depressed, diabetic South Asian man with Chronic Obstructive Pulmonary Disease, taking steroids, with chronic kidney disease, living in a small council house in the UK then your odds of dying of CVD in the next year are pretty damned high. What should such a person do? Write a will, I would think.

Not many of us are at such high risk. Few of us are in such a bleak situation. What can the average person do to shift those odds in your favour? If you have read this blog from start to finish, I would imagine that you already know. If not, I am going to tell you next time. I am going to tell you how to change the odds, but I am unable to tell you how to get them to zero.

1: https://www.eurekalert.org/pub_releases/2016-05/kp-crt042916.php

2: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0174944

3: https://www.cureus.com/articles/11752-a-72-year-old-patient-with-longstanding-untreated-familial-hypercholesterolemia-but-no-coronary-artery-calcification-a-case-report

27th November 2018

A number of people have written to me asking how to read all the articles I have written on cardiovascular disease. I understand it is not exactly easy to do this. So, here I am going to attempt a short summary of everything I have written up to now.

Thrombogenic theory vs. LDL/cholesterol hypothesis

Since the mid-nineteenth century there have been two main, and almost entirely conflicting, hypotheses as to what causes cardiovascular disease. At present it may seem as if there is only one, the cholesterol or LDL hypothesis. Namely that a raised low-density lipoprotein is the underlying/primary/necessary cause.

I am not running through all the reasons why this hypothesis is wrong here. I will confine myself to one simple point. For the LDL hypothesis to be correct, it requires that LDL can travel past the lining of the artery, the endothelial cells, and into the artery wall behind. This is considered the starting point for atherosclerotic plaques to form.

The problem with this hypothesis is that LDL cannot get into any cell, let alone an endothelial cell, unless that cell wants it to. We know this, for certain, because the only way for LDL to enter any cell, is if the cell manufactures an LDL receptor – which locks onto, and then pulls the LDL molecule inside. There is no other passageway. This is an inarguable fact.

If LDL cannot enter a cell, unless allowed to do so, then it cannot pass through a cell, unless a cell wants it to. It most certainly cannot exit the other side of a cell, unless granted passage.

Others have argued that, oh well, the LDL simply slips through the gaps between endothelial cells and that is how it gets into the artery wall. Again, this is impossible. There are no gaps between endothelial cells. Endothelial cells are tightly bound to each other by strong protein bridges, known as ‘tight junctions.’

These tight junctions can prevent the passage of single ions – charged atoms – which makes it impossible for an LDL molecule to slip through, as it is many thousands of times bigger than an ion. This, too, is an inarguable fact.  Ergo, the initiation of an atherosclerotic plaque (the underlying problem in cardiovascular disease) cannot be triggered by LDL leaking into an undamaged artery wall.

Which means that, if you want to get LDL (or anything else) into the artery wall, you first must damage the endothelium/lining of the artery. This has been accepted by the mainstream medical world, although you wouldn’t really know it, because they don’t exactly shout it from the rooftops.

Here, however, is a quote from the National Heart Lung and Blood Institute in the US. An organisation which is as mainstream as it gets:

Research suggests that coronary heart disease (CHD) starts when certain factors damage the inner layers of the coronary arteries. These factors include:

• Smoking
• High levels of certain fats and cholesterol in the blood
• High blood pressure
• High levels of sugar in the blood due to insulin resistance or diabetes
• Blood vessel inflammation
• Plaque might begin to build up where the arteries are damaged

It has taken them a long time to admit that damage must come first, but it is inescapable when you think about it. For once, I am completely in agreement with the mainstream on this, the initial step.

However, it is what happens next, where we rapidly diverge in our thinking. The mainstream believes that, after damage has occurred, it is LDL, and only LDL, leaking into the artery wall that triggers a whole series of downstream reactions that lead to plaques forming.

However, once you have damaged the endothelium there is no longer a barrier to stop anything getting into the artery wall. So, why pick on LDL? You also have proteins, red blood cells, platelets and Lp(a) and VLDL. Indeed, anything in the bloodstream now has free entry.

It particularly makes no sense to pick on LDL, as there is already plenty of LDL in the artery wall to start with. It gets there via the vasa vasorum (blood vessels of the blood vessels) which supply the largest blood vessels with all the nutrients they need, and through which LDL can freely flow into, and out of, the artery wall.

Which begs a further question. Why should the LDL that gets into the artery wall, from the blood flowing through the artery, cause a problem, when the LDL that is already there – does nothing? The more you look at it, the more ridiculous the LDL hypothesis becomes.

A counter hypothesis is as follows.

If you damage the endothelium, the first thing that happens is that a blood clot forms at that point. This has been known for a long time. I was sent an article a while ago, written as far back as 1959. The findings stand today:

‘…any intimal injury can very easily precipitate a local process of coagulation, platelet agglutination and fibrin deposition.’¹ [a.k.a. a blood clot]

You may wonder where the word ‘intima’ just appeared from. The endothelium, and the thin layer underneath the endothelial cells is sometimes called the ‘intima.’ Sometimes it is called the endothelial layer, some people call it the epithelium, or the epithelial layer. What you never get, in medicine, is people calling it the same thing… the same damned thing. Thank God these people don’t make aeroplanes, is all I can say.

Anyway, damage the endothelium, and a blood clot will form. This is the main mechanism the body uses to stop itself from bleeding to death. Damage the artery/endothelium → underlying artery wall exposed → blood clot forms → life continues.

What then happens? Well, most of the blood clot is shaved down in size by plasmin, an enzyme designed to break up (lyse) blood clots. Then a new layer of endothelium grows over the top of the remaining blood clot, and in this way, the clot becomes incorporated into the artery wall. Although I have added in a few extra bits, this is, essentially, the thrombogenic theory, first suggested by Karl von Rokitansky in 1852.

He proposed this because he noted that atherosclerotic plaques looked very much like blood clots, in various stages of repair. He further observed they contained red blood cells, fibrin and platelets, which are the main constituents of a blood clot. His ideas were then rubbished by Rudolf Virchow, who could not see how a blood clot could end up underneath the endothelium, and Rokitansky’s theory (almost) died a death.

However, from time to time, other researchers also noted that plaques do look awfully like blood clots. For example, a researcher called Elspeth Smith – who taught me at Aberdeen University. She had this to say

‘…in apparently healthy human subjects there appears to be a significant amount of fibrin deposited within arteries, and this should give pause for thought about the possible relationship between clotting and atherosclerosis.’ ²

As her paper went on to say:

‘In 1852 Rokitansky discussed the “atheromatous process” and asked, “In what consists the nature of the disease?” He suggests “The deposit is an endogenous product derived from the blood, and for the most part from the fibrin of the arterial blood”. One hundred years later Duguid demonstrated fibrin within, and fibrin encrustation on fibrous plaques, and small fibrin deposits on the intima of apparently normal arteries. These observations have been amply confirmed but, regrettably, the emphasis on cholesterol and lipoproteins was so overwhelming that it was another 40 years before Duguid’s observations had a significant influence on epidemiological or intervention studies.’

Finally, for now, Dr Smith stated this in another paper:

‘After many years of neglect, the role of thrombosis in myocardial infarction is being reassessed. It is increasingly clear that all aspects of the haemostatic system are involved: not only in the acute occlusive event, but also in all stages of atherosclerotic plaque development from the initiation of atherogenesis to the expansion and growth of large plaques.’³

What she is saying here is that every step of CVD is due to various aspects of blood clotting. You damage the artery wall, a blood clot forms, it is then incorporated into the artery wall. A plaque starts, then grows. This description of how CVD starts and develops, is the process that I believe to be correct. With a couple of provisos.

The main proviso is that endothelial damage is going on all the time, in everyone’s arteries, to a greater or lesser extent. Therefore, we are not looking at an abnormality, or a disease, or a ‘diseased’ process.

The formation of blood clots following endothelial damage is also a healthy, normal, process. If it did not happen, then we would all bleed to death. As can happen in haemophilia, where blood clots do not form properly, due to a lack of clotting factors.

The next normal healthy process is that any blood clots that form must be incorporated into the artery wall. That is, after having been stabilised and shaved down. If clots simply broke off and travelled down the artery, they would get stuck when the artery narrows and cause strokes and heart attacks – and bowel infarctions and suchlike.

In short, the only way to repair any blood clot that forms on the lining of an artery wall, is to shave it down, then cover it over with a new layer of endothelial cells. Incorporating it into the artery wall.

At which point, repair systems swing into action. The main repair agents are white blood cells called macrophages. These break down and digest any remnant blood clot, before heading off to the nearest lymph gland where they too are broken down, with their contents, and removed from the body.

This ‘repair’ process leads to, what is referred to as ‘inflammation’ in the artery wall. Once again, however, this is not a disease process, it is all quite healthy and normal.

Problems only start to occur when the rate of damage, and resultant blood clot formation, outstrips the ability of the repair systems to clear up the mess.

Thus:

damage > repair = atherosclerosis/CVD

repair > damage = no atherosclerosis and/or reversal of plaques.

What factors can lead to the situation where damage outstrips repair? First, we need to look at those factors that increase the rate of damage. There are many, many, things that can do this. Here is a list. It is non-exhaustive, it is in no particular order, but it may give you some idea of the number of things that can cause CVD, by accelerating endothelial damage:

• Smoking
• Systemic Lupus Erythematosus
• Use of oral steroids
• Cushing’s disease
• Kawasaki’s disease
• Rheumatoid arthritis
• High blood pressure
• Omeprazole
• Avastin
• Thalidomide
• Air pollution
• Lead (the heavy metal)
• Mercury
• High blood sugar
• Erythema nodosum
• Rheumatoid arthritis
• Low albumin
• Acute physical stress
• Acute mental stress
• Chronic negative mental stress
• Chronic Kidney Disease
• Dehydration
• Sickle cell disease
• Malaria
• Diabetes/high blood sugar level
• Bacterial infections
• Viral infections
• Vitamin C deficiency
• Vitamin B deficiency
• High homocysteine level
• Chronic kidney disease
• Acute renal failure
• Cocaine
• Angiotensin II
• Activation of the renin aldosterone angiotensin system (RAAS) etc.

Blimey, yes, that list was just off the top of my head, I could get you another fifty without much effort. And no, I did not just make it up. I have studied every single one of those factors, and many more, in exhaustive detail. The extent of how many factors there are, should not really come as a surprise to anyone, but it usually does.

After all, the bloodstream carries almost everything around the body, and the endothelium faces the bloodstream, it is the first point of contact. If damaging things are being carried about in the blood, the lining of the artery is going to be directly exposed to enemy attack.

Moving on, we need to look at factors that make the blood more likely to clot and/or make blood clots that are more difficult to shift. Again, in no particular order here and non-exhaustive:

• Raised fibrinogen levels
• High lipoprotein (a)
• Antiphospholipid syndrome (Hughes’ syndrome)
• Factor V Leiden
• Raised plasminogen activator inhibitor 1 (PAI-1)
• Raised blood sugar levels
• High VLDL (triglycerides)
• Dehydration
• Stress hormones/cortisol
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Acute physical stress
• Acute mental stress.

For good health, you want to maintain a balance between the blood being too ready to clot, and the blood not clotting when you need it to. If you turn down the blood clotting system, bleeding to death can be a problem. This can happen if you have haemophilia, or if you take warfarin – or any of the other drugs used to stop blood clots forming in Atrial Fibrillation. Aspirin can also lead to chronic blood loss, and anaemia.

Looking at it from the other angle. You do not want your blood to clot too rapidly, or else equally nasty problems can occur. Antiphospholipid syndrome (APS), is a condition where the blood is highly ready to clot (hyper-coagulable). It greatly increases the risk of CVD:

‘Patients with APS are at increased risk for accelerated atherosclerosis, myocardial infarction, stroke, and valvular heart disease. Vascular endothelial cell dysfunction mediated by antiphospholipid antibodies and subsequent complement system activation play a cardinal role in APS pathogenesis.’⁴

Just to look more closely at one other factor on the list, which is fibrinogen. This is a short strand of protein that is made in the liver. It floats about in the blood doing nothing very much. However, if a clot starts to form, or the clotting system is activated, fibrinogen ends up being stuck end-to-end to form a long thin, sticky protein strand called fibrin. This is a bit like the strands that make up a spider’s web.

Fibrin wraps around everything else in a blood clot and binds it all very tightly, creating a very tough plug. You would guess that if you have excess fibrinogen in the blood, more fibrin will form, creating bigger and more difficult to shift blood clots.  I was first alerted to the dangers of having a high fibrinogen level by the Scottish Heart Health study.

‘This large population study confirms that plasma fibrinogen is not only a risk factor for coronary heart disease and stroke, but it is also raised with family history of premature heart disease and with personal history of hypertension, diabetes, and intermittent claudication.’ ⁵

To my surprise, a raised fibrinogen was found to be the most potent risk factor in the Scottish Heart Health Study, ranking above smoking. Because I don’t want to make this blog too long, I will simply say that all the other things in the list above both increase the tendency of the blood to clot and increase the risk of CVD.

Finally, we can look at factors that impair the repair systems. There are two basic parts to the repair systems.

• Formation of a new layer of endothelium, to cover the blood clot
• Clearing away of the debris left by the blood clot within the artery wall

What sort of things stop new endothelial cells being created?

• Avastin
• Age – which reduces endothelial progenitor cells (EPC) synthesis
• Thalidomide
• CKD – reduces EPC synthesis
• Diabetes
• Omeprazole
• Activation of the renin-angiotensin aldosterone system (RAAS)
• And drug that lowers nitric oxide synthesis
• Lack of exercise.

What sort of things damage the clearance and repair within the artery wall?

• Steroids
• Age
• Immunosuppressants
• Chronic negative psychological stress
• Certain anti-inflammatory drugs
• Many/most anti-cancer drugs.

Knowing this, it seems counter intuitive that there has been a great deal of interest lately in using anti-inflammatory drugs to reduce the risk of CVD. My response to the idea that inflammation may cause CVD has always been that, the most potent anti-inflammatory agent known to man is cortisone/cortisol. This is one of the stress hormones, and it vastly increases the risk of CVD. As do immunosuppressants – which are also used to dampen down the inflammatory response.

On the other hand, inflammation is not always a healthy thing. There are many chronic inflammatory conditions such as: rheumatoid arthritis, Crohn’s disease, asthma, Sjogren’s disease and suchlike where the bodies immune system goes wrong and starts to see proteins within the body as ‘alien’ and attacks them. This can cause terrible damage.

The way to best treat (if not cure) these conditions is to use immunosuppressant drugs. Cortisol/cortisone – and the many pharmaceutical variants that have been synthesized from cortisol – is still widely used. Hydrocortisone cream, for example, is widely used in eczema.

Immunosuppressants are also commonly used in transplant patients, to stop the organ from being attacked by the host immune system. This is a good thing to achieve, but longer-term problems with CVD are now widely recognised.

‘With current early transplant patient and allograft survivals nearly optimized, long-term medical complications have become a significant focus for potential improvement in patient outcomes. Cardiovascular disease and associated risk factors have been shown in renal transplant patients to be related to the pharmacologic immunosuppression employed.’⁶

‘Taking high doses of steroids (glucocorticoids) seems to increase the risk of heart disease including heart attack, heart failure, and stroke, according to new research. Steroids fight inflammation and are often prescribed for conditions including asthma, inflammatory bowel disease, and inflammatory arthritis. Prednisone and hydrocortisone are two examples of steroids.

Yet well-known adverse effects of these potent anti-inflammatory medications can increase the risk of developing high blood pressure, diabetes, and obesity — risk factors for heart disease.’⁷

The question I suppose is, can CVD possibly be a form of autoimmune condition? It seems highly unlikely. Although the inflammatory system can go wrong in all sorts of way. You may have heard of Keloid scars. These happen when you damage the skin, and the resulting healing response can create a very large ‘hypertrophic’ and unsightly scar.

Perhaps if you damaged the lining of an artery, and this triggered the equivalent of a ‘keloid’ scar in the artery wall, then if you could dampen down this reaction, an atherosclerotic plaque would then be much smaller. In which case, an inflammatory could be of benefit.

However, as of today, the more potent the anti-inflammatory drug, the greater the increase in CVD. Which suggests that if you interfere with the healing response to arterial injury, you are going to make thing worse – not better.

In truth, the real reason why inflammation is being seen as a possible cause of CVD is because inflammatory markers can be raised in CVD. To my mind this just demonstrates that in people with CVD, lots of damage is occurring, therefore there is more repair going on, so the inflammatory markers are raised.

However, the mainstream has decided to look at this from the opposite side. They see a lot inflammation going on and have decreed that the inflammation is causing the CVD – rather than the other way around. Frankly, I think this is bonkers. But there you go.

Anyway, where has all this got us to. I shall try to achieve a quick summary.

The LDL hypothesis is nonsense, it is wrong, and it does not remotely fit with any other factors known to cause CVD.

The thrombogenic theory, on the other hand, fits with almost everything known about CVD. It states that there are three, interrelated, processes that increase the risk of CVD:

• Increased rate of damage to the endothelial layer
• Formation of a bigger or more difficult to remove blood clot at that point
• Impaired repair/removal of remnant blood clot.

Any factor that does one of these three things can increase the risk of CVD. Although, in most cases, a few factors probably need to work in unison to overcome the body’s ability to heal itself. Which means that people who have only one or two risk factors, are probably not going to be at any greatly increased risk. You need to have three or four, maybe more, and then things really get going.

There are a few things that I have mentioned that will greatly increase the risk of CVD with no need for anything else to be present. They are:

• Steroids/Cushing’s disease
• Chronic Kidney Disease
• Sickle cell disease
• Antiphospholipid syndrome
• Immunosuppressants
• Avastin
• Diabetes
• Systemic Lupus Erythematosus
• Kawasaki’s disease.

All of which means that – in most cases – CVD has no single, specific, cause. It should, instead, be seen as a process whereby damage exceeds repair, causing plaques to start developing, and grow – with a final, fatal, blood clot causing the terminal event. The next blog will be a review of the things that you can do to reduce your risk of CVD.

1: Astrup T, et al: ‘Thromboplastic and Fibrinolytic Activity of the Human Aorta.‘ Circulation Research, Volume VII, November 1959.

2: https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0049384894900493/first-page-pdf

3; https://www.sciencedirect.com/sdfe/pdf/download/eid/1-s2.0-0049384894900493/first-page-pdf

4: http://www.onlinejacc.org/content/accj/69/18/2317.full.pdf

5: https://heart.bmj.com/content/heartjnl/69/4/338.full.pdf

6: https://www.ncbi.nlm.nih.gov/pubmed/12034401

7: https://www.webmd.com/asthma/news/20041115/steroids-linked-to-higher-heart-disease-risk

1st November 2018

A raised blood pressure, as a clinical sign, has always rather perturbed me. At medical school we were always taught – and this has not changed as far as I know – that an underlying cause for high blood pressure will not be found in ninety per cent of patients.

Ninety per cent… In truth, I think it is more than this. I have come across a patient with an absolute, clearly defined cause for their high blood pressure about five times, in total, and I must have seen ten thousand people with high blood pressure. I must admit I am guessing at both figures and may be exaggerating for dramatic effect.

Whatever the exact figures, it is very rare to find a clear, specific cause. The medical profession solved this problem by calling high blood pressure, with no identified cause, “essential hypertension”. The exact definition of essential hypertension is ‘raised blood pressure of no known cause.’ I must admit that essential hypertension certainly sounds more professional than announcing, ‘oh my God, your blood pressure is high, and we do not have the faintest idea why.’ But it means the same thing.

Doctors have never been good at admitting they haven’t a clue about something. Which is why we have a few other impressive sounding conditions that also mean – we haven’t a clue.

Idiopathic pulmonary fibrosis – progressive damage of the lungs – and we don’t know why

Cryptogenic stroke – a stroke caused by something – but we don’t know what

Essential hypertension – high blood pressure – we haven’t a clue why its high.

Can you turn something into a disease, simply by giving it a fancy Latin title? It appears that you can. Does it help you to understand what you are looking at? No, it most certainly does not.

So, why does the blood pressure rise in some people, and not in others. It is an interesting question. You would think that, by now, someone would have an answer, but they don’t. Or at least no answer that explains anything much.

Excess salt consumption has been blamed by some. However, even if you take the more dramatic figures, we are talking no more than 5mmHg. Indeed, the effect of reducing salt intake on people without high blood pressure is about 1mmHg, at most

‘Almost all individual studies of participants with normal blood pressure (BP) show no significant effect of sodium reduction on BP.’ 1

Which would mean that the effect of raising salt intake would be almost zero. So, if it is not salt, what is it? A magic hypertension fairy that visits you at night? Could be, seems as likely as anything else.

When you have a problem that is difficult to solve, I always like to turn it inside out, and see what it looks like from the opposite direction. Presently, we are told that essential hypertension increases the risk of cardiovascular disease.

Looking at this from the other direction, could it be that cardiovascular disease causes high blood pressure. Well, this would still explain why the two things are clearly associated, although the causal pathway may not be a → b. It could well be b → a.

I must admit that I like this idea better, because it makes some sense. If we think of cardiovascular disease as the development of atherosclerotic plaques, leading to thickening and narrowing of the arteries then we can see CVD is going to reduce blood flow to vital organs, such as the brain, the kidneys, the liver, the heart itself.

These organs would then protest, leading to the heart pumping harder to increase the blood flow and keep the oxygen supply up. The only way to increase blood flow through a narrower pipe, is to increase the pressure. Which is what then happens.

Over time, as the heart is forced to pump harder, and harder, the muscle in the left ventricle will get bigger and bigger, causing hypertrophy. Hypertrophy means ‘enlargement.’ So, in people with long term, raised blood pressure, we would expect to see left ventricular hypertrophy (LVH). Which is exactly what we do see.

LVH is often considered to be a cause of essential hypertension. I would argue that LVH is a result of CVD. This is not exactly a new argument, but it does make sense.

Two models strongly support the idea that CVD causes high blood pressure. The first is a rare condition called renal artery stenosis. This is where an artery to one of the kidneys narrows, or starts life narrowed. This causes the kidney to protest at a lack of blood supply and increase the production of renin.

Renin converts angiotensinogen, a protein made in the liver that floats about in the blood, into angiotensin I. Then angiotensin converting enzyme (ACE) turns angiotensin I into angiotensin II. And angiotensin II is a very powerful vasoconstrictor (narrows blood vessels), this raises the blood pressure.

Angiotensin II also stimulates the release of aldosterone, a hormone produced in the kidneys. Aldosterone increases the reabsorption of sodium and water into the blood from the kidneys, simultaneously driving the excretion of potassium (to maintain electrolyte balance). This increases the volume of fluid in the body, which also increases blood pressure.

This whole system is called the Renin angiotensin aldosterone system (RAAS), sometimes shortened to RAS. Activate at your peril. Angiotensin II is, amongst other things, a potent nitric oxide (NO) antagonist. Which, as you might expect, can do very nasty things to endothelial cells and the glycocalyx (glycoprotein layer that protects artery walls).

If you discover that the patient with very high blood pressure has got renal artery stenosis, the artery can be opened, and the blood pressure will – in most cases – rapidly return to normal. Which proves that narrow arteries can, indeed, lead to high blood pressure.

The other model is the situation whereby a number of blood clots build up in the lungs, a condition known as chronic thromboembolic pulmonary hypertension. It is not nice. The arteries are effectively narrowed by blood clots – in order to keep the blood flow up, the heart must pump harder. In this case the right side of the heart because it is this side that pushes the blood through the lungs.

So, you usually end up with Right Ventricular Hypertrophy (RVH). Eventually the heart cannot pump any harder and starts to fail, leading to Right Ventricular Heart Failure (RVF). Shortly after this, you die.

There is an operation that can be done to remove all the blood clots from the lungs. It has a very high mortality rate. Basically, you open up the lungs and pull out a great big complicated blood clot, that looks a bit like a miniature tree. If the operation is not fatal (pulmonary endarterectomy), the blood pressure drops, the LVF improves rapidly, and the outcomes are excellent.

This is another example which demonstrates that a rise in blood pressure is caused by narrowed blood vessels. Again, if you open the blood vessels the pressure drops, the stress on the heart falls, and rapid improvement can take place.

So, if CVD causes high blood pressure, is there any point in trying to lower the blood pressure with drugs. After all, you are doing nothing for the underlying disease.

Well, you would be taking pressure off the heart, so you might be improving left ventricular hypertrophy, and/or left ventricular failure. But, of course, you also lowering the blood flow to important organs, which is not so good. Indeed, it is well recognised that, in the elderly, you can increase the risk of falls by lowering the blood pressure – which can lead to fractured hips, and suchlike.

Also, if you lower the blood pressure too much the kidneys start to struggle, another major problem in the elderly. In fact, I often tell nurses working with me in Intermediate Care that dealing with the elderly can turn into a battle between the heart and the kidneys. Get one under control and the other one goes off.

Then, if you lower the blood pressure you are in danger of triggering the RAAS system into action as the body tries to bring the pressure back up again, and the RAAS system can be quite damaging to the blood vessel themselves. You will definitely disrupt the control of blood electrolytes such as sodium and potassium as aldosterone kicks into action.

I am forever battling to keep sodium levels up and potassium levels down, or vice versa, depending on which anti-hypertensive are being used. All of these are reasons why I do not bother to treat high blood with drugs, until it is far higher than the current medical guidelines would recommend.

What I do recommend to patients is:

• Increase potassium consumption
• Go on a high fat, low carb diet
• Use relaxation techniques: mindfulness, yoga, whatever floats your boat
• Take exercise
• Get out in the sun – this stimulates NO synthesis
• Try L-arginine and L-citrulline – as above
• Increase magnesium consumption

This will often, if not always, do the trick.

If you must take medication, I was a very strong supporter of ACE-inhibitors, in that they blocked angiotensin II, and increased NO synthesis. Both good things. However, some research has come out recently, suggesting they may increase the risk of lung cancer. Not by a great deal, but there you go. Best to take nothing at all, if you possibly can.

1: https://www.cochrane.org/CD004022/HTN_effect-low-salt-diet-blood-pressure-and-some-hormones-and-lipids-people-normal-and-elevated-blood

11th October 2018

Blood pressure

I have tended to avoid talking about blood pressure, because I am not entirely sure what I think about it as a cause of CVD. However, since more people now take blood pressure lowering medication than any other type of medication in the world, including statins, it wold be remiss of me not to at least mention it.

Another problem is that, whilst blood pressure may seem a very simple subject. Either it is high, or it is not, nothing could be further from the truth. It is immensely complicated, and fragments rapidly into thousands of different strands, looping and whirling in front of you.

For example, let us take an apparently simple question, what is a high blood pressure? Well, with almost every passing year, this changes. The experts and the guideline writers get together on a regular basis and decide that well, hey ho, we thought 140/90 was high, turns out we are wrong. It is 130/85 – or whatever. By the way, the definition of a ‘normal’ blood pressure always goes down – never up. On current trends we should hit 0/0mmHg by the year 2067. What happens after that is hard to say.

I suppose a question that may seem reasonable to ask is the following; is average normal. Not, not even slightly. In a similar fashion to blood cholesterol levels, average and normal do not even remotely match up. Last time I looked eighty-five per cent of the population in almost all Western countries had high cholesterol levels. I would suspect another eighty-five per cent have high blood pressure.

In fact, if you wish to stretch logic to its very boundaries it is possible to propose that 99.9% of the population has a high blood pressure level. How can this make any sort of sense, you may ask? Well, in a moment of ennui I opened the American College of Cardiology/American Heart Association (ACC/AHA) risk calculator. You can find it here. http://www.cvriskcalculator.com/

I put in all my risk factors, kept them all the same, apart from my blood pressure which I started moving up and down, as you do when there is nothing good on the TV. What I found was that, as I reduced my blood pressure on the calculator, my CV risk went down, and down, until I got to a systolic (upper figure) of 90mmHg. You cannot make your blood pressure go any lower than this on the calculator.

The reason why you cannot get your blood pressure below 90mmHg is that if you go below this figure, you will be diagnosed with hypotension. Hypo = low. So, we have the weird situation whereby at 90mmHg your blood pressure is perfect. Above this, your risk of CVD goes up, below this the pressure is dangerously low and should be raised.

Therefore, at exactly 90mmHg your blood pressure is ‘normal’. At any other pressure it is abnormal – in that it increases the risk of death. Which is the definition of any ‘abnormal’ clinical test. It must be said that this constitutes a pretty narrow range. A doctor should be trying to keep your systolic blood pressure between 90mmHg and 90mmHg. And good luck with that. A very delicate titration indeed.

Clearly this is nuts, and it is not based on any clinical data whatsoever. There has never been a study whereby the systolic blood pressure has been lowered to 90mmHg. Nor will there ever be one done. This, I can guarantee. The mortality rate would be catastrophic.

So, how is this figure arrived at?

It comes from a mathematical smoothing technique whereby you get all the points on a graph, then draw the ‘best fit’ line through them all. I include an example here, which is where someone (Zoe Harcombe actually) looked at the cholesterol levels and rate of death from CVD in every country in the world (these are the dots). As you can see everything is rather scattered. [Data taken from the World Health Organisation].

However, there is a trend here, and that trend can be worked out. In this case, you feed in all the data points and a formula works out the underlying association between cholesterol and CVD death. As you can see in this case, as cholesterol goes up – CVD deaths go down. If you half close your eyes (which gets rid of the outlying points) the association between the dots and the line seems clearer.

(Or maybe that is just me).

What does this prove? Well, it proves nothing very much, for certain. What it almost certainly disproves, however, is an association between raised cholesterol and CVD.

When it comes to blood pressure it cannot be denied that. as the blood pressure rises, the risk of CVD also rises. However, the association is non-linear. By this I mean that, if your blood pressure goes from 100mgHg to 110mmHg, the risk of CVD does rise (but not by a statistically significant amount]. It only rises very, very slightly.

From 110mmHg to 120mmHg another very slight rise

From 120mmHg to 130mmHg another very slight rise

It is only when you get to about 160mmHg that the risk suddenly starts to go up sharply. From then on, things become rapidly worse. So, if your systolic blood pressure is above 160mmHg you should probably do something about it. However, what is the risk for a systolic blood pressure below this? Here we must rely on mathematics.

A paper that I have mentioned a few times, because I think it is a belter is from the European Heart Journal – from the year 2000 (believe me nothing of significance has happened since then). It is entitled ‘There is non-linear relationship between mortality and blood pressure.’

It is worth quoting the first two paragraphs in full. Sorry, for those not of a scientific bent:

‘Stamler stated that the relationship of systolic blood pressure (SBP) to risk of death is continuous, graded, and strong, and there is no evidence of a threshold…’ The formulation of this ‘lower is better’ principle, in terms of the linear logistic model (often referred to simply as the linear model) is the paradigm for the relationship of all cardiovascular risks to blood pressure and form the foundation for the guidelines for hypertension [and still does].

But it is often forgotten that when a study reports a linear (or any other) relationship between two variables it is not the data itself, but the model used to interpret the data, that is yielding the relationship. Almost universally, studies that report a linear relationship of risk to blood pressure do so via the linear models, such as the Cox model, or the linear logistic model.

Formally that model can be applied to any bivariate data and, independently of the data will always show that there is a linear relationship between the two variables. Before one can have confidence that the stated linearity correctly reflects the behaviour of the data, and is not just an artefact of the model, it is necessary to carefully examine the data in relation to the proposed model. At a minimum, it must be demonstrated that the model actually ‘fits’ the data and that it does not ‘smooth away’ important features of the data.’ ¹

To paraphrase, your carefully constructed mathematical model may well be bollocks. In fact, it most probably is.

The statisticians who wrote this paper went back to the Framingham study – from whence all guidelines on blood pressure have since flowed, in all countries, everywhere – and found that the data ‘statistically rejected the model.’ They made the following statement ‘the paradigm MUST be false.’

I hate to say it, but the first person to recognise that the linear model ‘in terms of the relationship of overall and coronary heart disease death to blood pressure was unjustified.,’ was Ancel Keys. I am not sure what to make of that, as Keys is my number one medical historical villain. Still, he wasn’t stupid.

Anyway, the response to the European Heart Journal paper was…. Complete silence. Nothing. No counter arguments were proposed, nothing. “First they ignore you, then they laugh at you, then they fight you, then you win.” Gandhi. In this case we never got beyond ‘first they ignore you.’ Oh well, such is life.

None of this means that blood pressure has no role to play in CVD – or vice-versa – I just wanted to make it clear that that the whole area has become such a mess that it is very difficult to see through the forest of bias. What is a fact here? Frankly, sometimes, I have no real idea.

So, where does this leave us regarding blood pressure and CVD? It leaves us with only a few certainties. First, and most important, the only blood vessels in the body that normally develop atherosclerosis are the larger arteries. These blood vessels have a high blood pressure in them. Let us say around 120/70mmHg.

[120mmHg is equivalent to a column of water about three metres high. The units used to measure blood pressure are mmHg i.e., millimetres of mercury. Mercury was used to measure blood pressure, because it is many times denser than water. To measure blood pressure using a water sphygmomanometer would need a device more than three metres tall.]

On the other hand, the larger arteries in the lungs (pulmonary arteries) have an average blood pressure of around 20/6mmHg. In normal circumstances they never develop atherosclerosis. The veins have a blood pressure of about 6mmHg. It does not go up and down, because the pressure in the veins is unaffected by the pumping of the heart. The veins never develop atherosclerosis.

This makes it clear that the blood pressure, and turbulent blood flow, needs to reach a certain level before atherosclerosis can start. I sometimes liken this to a river flowing down a mountainside, with rushing and roaring and white water foaming and raging. That would be an artery. When the river reaches the plain below, the speed of water flow drops, the river widens and meanders. That would be a vein.

I think it is pretty clear that the lining of an artery is put under far more biomechanical stress than the lining of a vein – or a pulmonary artery. Which is why atherosclerotic plaques develop in [systemic] arteries, and nowhere else.

This idea is further supported by the fact that it is perfectly possible to get atherosclerotic plaques to develop pulmonary arteries, and veins. But only if you significantly raise the blood pressure. There is a condition known as pulmonary arterial hypertension (high blood pressure in lungs). There are many causes of this, and I am not going through them all here.

Let’s just say that people who suffer from pulmonary hypertension can, and do, develop atherosclerosis in the lungs. It should be pointed out that the pressure still gets nowhere near that in the rest of the body, perhaps 50/20mmHg, or suchlike. However, the blood vessels in the lungs were never designed to cope with high(er) blood pressure, and so damage will occur at a lower level.

When it comes to veins, if you take a vein from the leg, and use it as a coronary artery bypass graft (CABG), it will very rapidly develop atherosclerosis. Both of which prove that there is nothing inherently different about arteries and veins that normally protects veins and pulmonary arteries. It is all due to pressure.

Low pressure – no atherosclerosis

High pressure – atherosclerosis

So, surely the lower you get the blood pressure the better? Maybe, maybe not. There are many, many, other issues to be taken into account here – some of which I will discuss in the next blog.

1: Port S, et al: ‘There is a non-linear relationship between mortality and blood pressure.’ Eur Heart J, Vol 21, issue 20 October 2000