Heart attacks are caused by a disease called atherosclerosis, which clogs and narrows the arteries to the heart (coronary arteries) and elsewhere, including the brain.

Having a high level of cholesterol in the blood, or other abnormal levels of fats (especially low levels of a 'good' type of cholesterol called HDL-cholesterol), is one of the main factors leading to atherosclerosis.

Other important factors include smoking, high blood pressure, being overweight, being inactive and having diabetes.

If you've had one heart attack, you have a greater than 30 per cent (ie one in three) risk of dying or developing complications from heart disease in the next ten years. Fortunately, you can reduce this risk with a combination of lifestyle changes and drug treatments, including statins.

Lowering cholesterol

Statins are drugs that help to reduce cholesterol levels and alter fat levels in the blood to a more normal profile. They work by blocking an enzyme needed for cholesterol production, mostly in the liver.

Medical trials have shown that lowering cholesterol reduces the risk of cardiovascular disease (CVD) and death in those at increased risk (such as yourself). In a round up of 14 trials of statins which included more than 90,000 patients, the Cholesterol Treatment Trialists' Collaboration showed that by reducing the blood level of the harmful type of cholesterol (low-density lipoprotein or LDL cholesterol) by 1 mmol/l it was possible to reduce the risk of dying from coronary heart disease by 23 per cent. The risk of stroke was also reduced by about 21 per cent (these benefits have also been shown with other ways of lowering cholesterol, not just by use of statins).

The general aim of treatment is to reduce cholesterol levels by 20 to 25 per cent, or to below 5mmol/l (which adds up to a lowering of around 1 mmol/l as the Collaboration recommended). Some experts simply say that the lower the cholesterol the better.

NICE, the National Institute for Clinical Excellence, has made the following recommendations about the use of statins to prevent cardiovascular events such as heart attacks.

• All adults with clinical evidence of CVD should receive statin treatment. (This means adults who have had a heart attack or who have a condition such as angina or peripheral arterial disease.)
• Adults who have a 20 per cent or greater risk of developing CVD in the next ten years should receive statin treatment.

It's usually a long-term treatment - you may have to take statins (or find some other way to reduce your cholesterol) for the rest of your life.

Side-effects

Tummy upsets, muscle aches and liver problems are among the common side-effects of statins. Most of these settle with time. But, as with any other medicine, if you have problems which you think are the result of your treatment, you should seek the advice of your GP, who may be able to recommend an alternative.

Statins can't be used by people who have liver disease or drink heavily. People who are using statins should make sure their GP tests their liver with a blood test at regular intervals.

Lifestyle changes

It's essential that at the same time as taking statins, you make some lifestyle changes to reduce the risks:

• Stop smoking: lifelong smokers are twice as likely to have, or die from, heart disease as non-smokers. The risk falls rapidly after stopping smoking, although it may be 20 years, if ever, before the risk is completely reversed. Giving up can nearly halve your risk and may mean that you no longer need statin treatment.
• Dietary changes: reduce the amount of fat (especially saturated fat), eat five portions of fresh fruit and vegetables a day, cut salt by a third and have two portions of fish (one oily) a week.
• Take regular exercise: moderate activity reduces your risk by one third.
• Control high blood pressure or diabetes.

This article was last medically reviewed by Dr Trisha Macnair in July 2008