By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

The statin group of drugs (also known as HMGcoA reductase inhibitors) has proven to be very effective at lowering blood cholesterol levels and also at preventing heart attacks, which is one of the main consequences of a high cholesterol. The process by which cholesterol causes the damage is known as atherosclerosis and involves the build-up of cholesterol-containing plaques in the walls of the arteries, which can eventually block them altogether. The plaque in the arteries supplying the heart results in a heart attack, and in the arteries supplying the brain, it causes a stroke. However, not all strokes are caused by blockage of a major artery, and cholesterol is less important as a risk factor for strokes than heart attacks.

Dr. Heiner Bucher and his colleagues have performed an analysis of the results of 28 clinical trials that compared the effects of a statin drug and an inert placebo on patients who already had coronary heart disease or were at very high risk for it. The intention of all of the trials was to see if the statin drugs would reduce the occurrence of heart attacks, but they also evaluated the effect on strokes. The authors of this analysis also reviewed the results from comparable studies in which cholesterol was lowered by other drugs or by diet alone.

The combined results from the different studies showed that statins lowered the risk of stroke (fatal or non-fatal) by 24%, while the risk of a fatal heart attack was cut by 31%. Studies in which cholesterol was lowered either by other drugs (such as cholestyramine and gemfibrozil) or by diet did not show any consistent effect on the rate of either strokes or heart attacks.

Doctor's comments

This study is technically a meta-analysis, i.e. - a study in which the results of several studies examining the same question are pooled to give a single estimate of the effect, which in this case was the extent to which statin drugs protect against strokes. We point out that prevention of stroke was not the primary objective of any of the studies; the participants were selected because they already had manifestations of heart disease (such as angina or a previous heart attack) or were at high risk for it as a result of high cholesterol and other risk factors. The findings, while encouraging, do not necessarily apply to people who are at risk of a stroke simply because they have high blood pressure.

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