Prevention of heart disease is still a challenge

MEDICAL MATTERS: The Score system estimates our 10-year risk of dying from cardiovascular disease

I HAVE HAD a run of patients recently who were hospitalised for acute coronary syndromes and heart attacks but who had normal cholesterol levels when they were admitted.

Last week, one of them, a man in his early 50s, expressed a not unreasonable frustration that despite normal cholesterol, normal blood pressure and never having smoked, he still ended up in the local coronary care unit.

As he saw it, he had looked after his health fairly well and was more than a little angry to have suffered cardiac damage without having “earned it” from a burger-eating, chain-smoking and beer-swilling existence.

Research published in the current issue of the American Heart Journal suggests he is not alone. The study of 137,000 patients hospitalised with a heart attack found that nearly 75 per cent had cholesterol levels that would indicate they were not at high risk of a cardiovascular event.

Specifically these patients had a low-density lipoprotein (LDL) – the bad cholesterol – level that met current guidelines. The researchers, from the David Geffen School of Medicine at University of California, Los Angeles, found that half of the people with a recent heart attack had LDL cholesterol levels below the targets that indicate a person is at moderate risk of heart disease.

So what does this mean for the prevention of heart disease? The lead author of the paper, Prof Gregg Fonarow, was in no doubt: “Almost 75 per cent of heart attack patients fell within recommended targets for LDL cholesterol, demonstrating the current guidelines may not be low enough to cut heart attack risk in most who could benefit,” he said.

It also reinforces the view that it is those at high risk who benefit most from the modification of cardiac risk factors. Indeed the 2007 prevention guidelines from the European Society of Cardiology (ESC) suggest doctors give those at most risk the highest priority.

For the rest of the population, the ESC recommends using the Systematic Coronary Risk Evaluation (Score) system. It estimates the 10-year risk of dying from cardiovascular disease and is based on sex, age, smoking, total cholesterol levels and systolic blood pressure.

Readers may wish to check out the electronic, interactive version of Score at www.heartscore.org. You will see it takes the form of a user-friendly coloured chart with four columns. It is easy to calculate your 10-year-risk of a fatal cardiac event which will vary from less than 1 per cent to 15 per cent or greater.

The system does not include additional risk factors such as obesity, diabetes or a family history of heart disease. If you have any of these, then your risk is automatically higher than that calculated by the Score system.

And, of course, if you have had a heart attack or a stroke, then you are already in a high risk category and should be seeing your doctor on a regular basis.

Because the Score system is designed to apply to a broad population base, it may underestimate the risk of disease in people with central, abdominal fat and those with low levels of “good” HDL cholesterol. Social deprivation also adds to the calculated risk and has been linked with a reduced ability to adopt lifestyle changes.

For those of us at high risk of a future heart attack or stroke, a measurement of inflammation in the body is a good idea. Blockages in coronary arteries remain stable for a long period of time, but if they become inflamed they are more likely to break off and cause a problem.

So measuring a person's high sensitivity C Reactive protein (hs CRP) may be helpful. A major study published at the end of 2008 – The Jupiter Study– found that apparently healthy subjects with elevated hs CRP levels treated with a statin drug had fewer heart attacks or strokes than those not treated. However, the number of people needed to treat to prevent one adverse event was high.

So my patient’s annoyance was understandable. Despite our extensive knowledge of coronary heart disease, implementing primary prevention remains a challenge.

Dr Houston is please to hear from readers at mhouston@irishtimes.com but regrets he is unable to reply to individual medical queries