Takeheart Health Check      

Cholesterol and Heart Attack Prevention

The incidence of coronary heart disease is very high in the United Kingdom, but elsewhere in the world it is often much lower. Epidemiological studies show a strong correlation between the average serum cholesterol of a population and its rate of CHD. (479)

Large clinical trials have demonstrated that lipid-lowering therapy reduces cardiovascular morbidity and mortality, and overall mortality, in both patients with established coronary heart disease and those at high risk of developing it. The debate about cholesterol lowering has, therefore, moved from the questions of efficacy and safety to those of cost, cost-effectiveness and patient selection. (478). For a readable summary of the evidence for the use of statins see 503.

A normal cholesterol is taken as below 5·2 mmols per litre. It is wise for you to aim for a level somewhat below this. If your level is consistently high it can usually be reduced by dietery measures and by desisting from smoking.

Mean cholesterol level of young adults in London is 5.8, in South Italy it is 4.7 and in South Japan 3.9 (The Oxford Textbook of Medicine).

There is no normal range for lipids, but a continuous gradation of risk.

High levels resistant to diet may require medication under the supervision of your physician.

Some families have a tradition of very high cholesterol levels. They should be under medical supervision. For a succint resumé of the familial hypercholestyerolaemia story.

Favourable changes in the lipid profile of Finnish MPs indicates that national cholesterol campaigns have impacted even on decision makers. (466)

In the United Kingdom cholesterol is usually expressed as so many mmols per litre. In other places it is sometimes expressed as mgs per decilitre. 5·2 mmols per litre is the same as 200 mgs per decilitre (multiply or divide by 39 to convert from one to the other).

Total cholesterol and high density lipoprotein cholesterol (HDL) can both be measured on a random (ie non-fasting) specimen of blood. The patient should have been on their habitual diet for two weeks, have no major illness, operation or injury for 2-4 weeks and no febrile illness for one week (The Oxford Textbook of Medicine).

The Statins

• The Scandinavian Simvastatin Survival Study - 4S (323)
  Coronary heart disease patients with blood cholesterol levels between 5.5 and 8.0 mmols/l (215-312 mgs/100 mls) treated with simvastatin (Zocor) have their cardiac mortality reduced by 42% and their overall mortality by 30%.
• The Cholesterol and Recurrent Events Study (CARE) (353).
  Post infarct patients with blood cholesterol levels below 6.0 mmols/l (234 mgs/100mls) treated with pravastatin (Lipostat) have a 24% reduction in fatal coronary events, a 26% reduction in bypass grafting, a 23% reduction in angioplasty and a 30% reduction in stroke. Their overall mortality is not reduced.
• The Heart Protection Study (HPS) (511).
  Patients with coronary heart disease, other occlusive arterial disease or diabetes, treated with simvastatin (Zocor) have a 12% reduction in all-case mortality, an 18% reduction in coronary mortality, a 25% reduction in stroke and a 22% reduction in revascularisation..
• The West of Scotland Coronary Prevention Trial (WOSCOP) (355)
  In people with raised cholesterol but without clinical heart disease, treatment for five years with pravastatin (Lipostat) reduces their mortality by 22% from 4.1 to 3.2%.

Sounds Good?

But

• It takes a very large trial to show these effects.
• A 33% relative reduction in mortality in a population at 3% risk of death per year is an absolute benefit of 1%. This is one less death per year - 99 people out of 100 will get no benefit that year.
• Statins do have side effects. They have not been around long enough for long term troubles to show up. Cerivostatin (Lipobay) has already been withdrawn.
• Statins are expensive. They could bankrupt the NHS. It has been estimated that the cost of a life-year gained to be in the order of £350,000 for a woman of 50 with angina and £1,000,000 for a man in his thirties without apparent coronary heart disease. Compare this with £100 per life-year gained with aspirin. (510).