Yale study shows aspirin as effective as anti-clotting drug in reducing post-heart attack risk

November 09, 1999

New Haven, Conn. -- Heart attack sufferers can benefit as much from taking one aspirin a day after their trauma as from taking aspirin along with a powerful anti-clotting drug, a Yale study shows.

The study, one of the largest of its kind, appears to settle the controversy over the best long-term treatment for heart attack sufferers ­ aspirin or the anti-clotting drug, Coumadin. The study recommends aspirin alone; it is cheaper and, unlike Coumadin, does not require monitoring to regulate the dosage.

The six-year randomized study included 5,059 subjects, all of them U.S. veterans. Half of the patients in the trial were given 162 mg of aspirin and the other half were administered 81 mg of aspirin plus a variable dose of Coumadin.

"There was no difference between the two groups in terms of total mortality, cardiovascular mortality, non-fatal myocardial infarction, and non-fatal stroke," said Michael Ezekowitz, M.D., professor of internal medicine and cardiology at the Yale School of Medicine. "It means that there is no added value to adding Coumadin to aspirin."

The Combined Hemotherapy and Mortality Prevention study (CHAMP) was released at the American Heart Association meeting in Atlanta.

The hypothesis of the study, which was designed and conducted with co-principal investigator Louis Fiore, M.D., a hematologist at the Veterans Administration Hospital in Boston, was that aspirin and the anti-coagulant Coumadin taken together would give the subjects added benefit. But the researchers found otherwise.

"Aspirin and Coumadin are the two strongest candidates to prevent blood clotting in the coronary vessels after patients have had a heart attack," Ezekowitz said. "The study shows that aspirin is equally effective as the combination. Also, aspirin is recommended over a combination of aspirin and Coumadin because aspirin is less costly and does not require monitoring to regulate the dose."

The study's subjects were selected from among 20,036 potential trial participants, all of whom had suffered heart attacks. Patients were excluded from the study because, among other reasons, they already were taking Coumadin, they suffered from another serious disease, or they were considered at high risk for bleeding.

The study, funded by the U.S. Veterans Administration, was started in 1992 and ended at the end of 1998. The biostatistician on the research project was Peter Peduzzi, M.D., assistant professor in epidemiology and public health at Yale and director of the clinical trials coordinating center at the VA Hospital in West Haven, Conn.

Ezekowitz said further analyses will be performed to see if there are subgroups of patients who had a heart attack and may benefit from the combination or whether there are groups of patients in whom higher doses of Coumadin may be of value.

Coumadin is the leading orally active blood-thinning medication. It came on the market about 50 years ago. Aspirin has been available for a century.

Ezekowitz said that Coumadin is the drug of choice for most patients who have atrial fibrillation, which is a condition where the receiving chamber of the heart, the atrium, shivers rather than contracting normally. He reported in a study published in the New England Journal of Medicine in 1992 that Coumadin reduces strokes in patients with atrial fibrillation.

"We showed then that we could reduce the incidence of stroke by 79 percent in these patients," Ezekowitz said. "We're not saying that patients should not take Coumadin. It has very important indications that are very valuable. But in this particular situation, it doesn't seem to have any benefit over aspirin alone."

Yale University

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