Fewer 1st Heart Attacks Occur in Aspirin Study
A major new study has found that an aspirin every other day may be highly effective in preventing first heart attacks.
In an article scheduled for Thursday publication in the New England Journal of Medicine, researchers said that aspirin was so effective in reducing the risk of a heart attack that they prematurely terminated the long-term study so that all 22,071 participants, half of whom did not take aspirin, could benefit from the newly gained knowledge.
An editorial by Dr. Arnold S. Relman, the highly respected editor of the weekly journal, called the study “a milestone in the continuing struggle” against heart attack.
The finding has broad implications because an estimated 1.5 million Americans suffer first heart attacks each year and a third of them die as a result.
In the 57-month study, whose participants all were male physicians, 104 out of the 11,034 who took aspirin had heart attacks, compared to 189 heart attacks in the 11,037 who took only a sugar pill, or placebo. Statistically, these numbers mean that ordinary aspirin reduced the heart attack risk for healthy individuals by as much as 47%.
Previous studies have shown that daily aspirin use by heart attack victims could reduce the number of second heart attacks and thereby save as many as 50,000 lives per year. Such aspirin therapy is now routine for heart attack victims.
But the new study is the first to show that aspirin can reduce the risk of first heart attacks.
Despite that finding, however, physicians Tuesday were not ready to recommend that everyone take aspirin.
Caution Urged
“There are a number of people who can benefit from this treatment, but I hope not everybody in the U.S. is going to take aspirin every morning,” said Dr. Claude Lenfant, director of the National Heart, Lung and Blood Institute, which sponsored the study.
Researchers are concerned about the possibility of such widespread use because aspirin has many side effects.
For one thing, the incidence of stroke was about 15% higher in the aspirin group, with 80 strokes, compared to 70 in the placebo group.
But the increase in strokes was so small that “it may be only chance, while the decrease in heart attacks was very clear,” said cardiologist George B. Hutchinson of Harvard Medical School.
“All we can conclude is that it will be necessary for physicians to balance the risk of stroke and heart attack for each patient,” he added.
Also, prolonged aspirin use can cause stomach and gastrointestinal upset and bleeding. Other medical conditions that would bar the use of aspirin include kidney or liver disease, peptic ulcer, gastrointestinal or other bleeding problems and a history of certain types of stroke.
Effect on Women
Further, there is virtually no evidence that aspirin would confer a similar protection to women, although “there is no reason to believe women will respond differently,” Hutchinson said. Women were not included because their risk of heart attack is only about 25% that of men, and thus would have required a much larger study population.
Scientists have long known that aspirin can impair the clotting ability of blood by stimulating the production of hormone-like molecules called prostaglandins throughout the body. It is apparently unique in this ability.
No evidence has been found that aspirin substitutes such as acetaminophen (Tylenol) or ibuprofen (Advil) have similar abilities.
Because most heart attacks are caused by the formation of a clot that blocks a blood vessel supplying the heart, cardiologists speculated that aspirin could reduce the danger of attacks by inhibiting clot formation.
At least seven long-term studies of more than 11,000 heart attack victims have shown that one-half or one aspirin per day can reduce the risk of a second attack by as much as 20%.
A similar number of studies have also shown that daily doses of aspirin can reduce the risk of strokes caused by clot formation in the brain by as much as 40%.
Causes of Strokes
Such strokes, called ischemic strokes, account for 70% to 80% of all strokes, according to the American Heart Assn. The remainder of strokes are caused by excessive bleeding, and aspirin would increase their severity.
In the new study, six in the aspirin group had strokes caused by bleeding, compared to only two in the control group.
Based on the earlier studies involving heart attack and stroke patients, the Physicians’ Health Study Research Group was formed at the Harvard Medical School in 1982 to study whether aspirin could prevent heart attacks in healthy individuals and whether a drug called beta carotene could prevent cancer.
A total of 33,223 healthy physicians between the ages of 40 and 85 were recruited. After an initial 18-week study, the researchers excluded 11,152 who did not comply with the daily pill-taking regimen or who reported adverse reactions to either aspirin or beta carotene.
Half of the remainder received an aspirin (Bufferin) every other day. A special committee monitored the number of heart attacks and deaths on a regular basis.
By last December, the committee had concluded that it was not ethical to continue the study, said Hutchinson, who chaired it. “We couldn’t keep going because the number of (heart attacks) was so much decreased that we were obliged to let the subjects and the general public know,” he said.
Letters to Participants
Letters explaining the results were sent to the participants to coincide with publication of the results in the New England Journal. Officials of the National Heart, Lung and Blood Institute were to hold a press conference today in Bethesda, Md., to discuss the results.
Earlier this week, results of the impending report were being widely circulated by aspirin manufacturers, and Reuter news agency Tuesday reported those results, citing anonymous industry sources.
The beta carotene study, however, will be continued until its scheduled end in 1990, Hutchinson said.
Drug companies expected to profit from new aspirin study. Story in Business.
