(February 2001)

If you have had a heart attack or a mild form of stroke (called a TIA - transient ischemic attack), taking aspirin under a doctor’s guidance can reduce the risk of a full blown stroke or another heart attack by about 25 percent.

The important question that is still not resolved is whether an apparently healthy person with no symptoms of a stroke or evidence of coronary heart disease benefits from taking low doses of aspirin daily or several times a week. That is the subject of an article in the British Medical Journal July 1, 2000. The investigators from the British Medical Research Council followed 5,499 men ages 45 to 69 years for six to eight years, some of whom received aspirin 75 milligrams (a low dose) daily. These men were considered to be in the top 20 percent in regard to risk of heart attack. Aspirin did reduce the risk of non-fatal heart attack by 32 percent. The intriguing finding was that all the benefit was found for those with lower blood pressures. If the systolic blood pressure was less than 130 millimeters of mercury, the risk of heart attack was reduced by 45 percent (due mainly to a reduction in non-fatal heart attacks) and stroke by 59 percent. A smaller reduction in risk of coronary heart disease (25 percent) was found for those with blood pressure between 130 and 145 millimeters of mercury.

On the other hand, for those with systolic pressures of 145 millimeters of mercury or above, there was no benefit at all in regard to heart attack and a 42 percent increase in risk of stroke.

The reduced risk of non-fatal heart attack appeared to occur primarily in younger men. There was no benefit from aspirin and perhaps even increased risk of death from heart attack in the oldest men studied, those 65 to 69 years of age.

The authors noted that those with higher blood pressures not only show no benefit from aspirin, but also may be exposed to the risk of bleeding into the brain or the intestinal tract from the aspirin.

They concluded "the benefit of low dose aspirin may occur mainly in those with lower systolic pressures, although it is not clear even in these men that the benefit outweighs the potential hazards".

Commentary: This is a very interesting study. It seems to say that, if you have a major risk factor for heart attack and stroke, high blood pressure (or even high normal blood pressure), aspirin will not overcome that risk factor and prevent a heart attack or stroke. For those with higher blood pressures (even in the high normal range), not only was there no benefit, but also there was increased risk of serious bleeding into the brain or intestinal tract.

For those with lower systolic pressures (130 millimeters or less), there seems to be clear benefit in younger men (under age 65) in regard to non-fatal heart attacks and stroke. But, even here, the authors are not willing to advocate aspirin use. The reason for this is that only a small minority of the men suffered a heart attack or stroke. Those not destined to have a stroke or heart attack will still have to worry about an increased risk of bleeding. Besides the overall death rate from heart attack was not reduced by aspirin, indicating that aspirin did not protect from the more severe heart attacks; and fatal strokes occurred twice as frequently among aspirin takers.

This study, showing that blood pressure is an important variable in regard to possible benefits of aspirin, needs confirmation by other studies, but, at present, anyone with no history of coronary heart disease or stroke with a blood pressure over 145 millimeters of mercury systolic should not use aspirin to prevent heart attack or stroke. Those with lower blood pressures must balance modest potential benefit against modest potential harm. Those over age 65 with no history of coronary heart disease should not be using aspirin to prevent heart attacks regardless of blood pressure.

Until there are more data available, Healthful Life will not recommend aspirin for apparently healthy adults to prevent heart attack or stroke. The findings here apply to men; presumably, the same is true of women.

Meade, T.W. and Brennan, P.J. Determination of who may derive most benefit from aspirin in primary prevention. British Medical Journal. Vol 321 (July 1) Pgs 13-17. 2000.