Low-dose aspirin is best choice for cutting bleeding risksAmerican Heart Association A little aspirin goes a long way in helping to prevent heart attacks and strokes while reducing bleeding complications, according to a study published in today's rapid access Circulation: Journal of the American Heart Association. The new findings emerged from a large international clinical trial called Clopidogrel in Unstable Angina to Prevent Recurrent Events (CURE). The study tested a combination of two antiplatelet agents that help prevent blood clots: aspirin and clopidogrel. CURE participants had unstable angina, which is chest pain due to restricted blood flow to the heart muscle.  Blood clots are a major cause of heart attacks and strokes. The main goal of the trial was to test the effectiveness of clopidogrel and aspirin versus aspirin alone. CURE researchers reported last year that patients in the combination arm suffered significantly fewer severe cardiovascular problems than the aspirin-only group — 9.3 percent compared to 11.4 percent. However, the study also provided an opportunity to assess the safety and efficacy of various aspirin doses, with or without clopidogrel. "Experimentally, a single 100-milligram dose of aspirin is sufficient in healthy individuals to inhibit platelet aggregation," said lead author Ron J. G. Peters, M.D., of the Academic Medical Center in Amsterdam, The Netherlands. The researchers suggested that the optimal daily aspirin dose for reducing acute coronary syndromes (ACS) may be between 75 and 100 milligrams (mg). ACS is a general term for heart attack or angina. Peters said the findings from CURE could lead to a significant change in the aspirin dose recommended for ACS patients. CURE researchers said their new analysis demonstrates three important points:
The CURE study compared the daily use of aspirin alone with aspirin plus clopidogrel in 12,562 ACS patients. All patients were prescribed aspirin, with the dose determined by the participating medical institution, and the patients were randomized to receive clopidogrel or a placebo for up to a year after admission. The CURE protocol recommended a daily aspirin dose between 75 mg and 325 mg. In the present analysis, aspirin use was divided into three groups; less than or equal to 100 mg., 101 through 199 mg., and 200 mg. or greater. Among the study participants, 5,320 received a low dose of aspirin, 3,109 took the medium dose, and 4,110 got a high dose. Peters noted that there is no uniformity in the aspirin doses used in clinical practice. Within each participating institution, aspirin dosage didn't vary significantly, but across geographic regions the range was much larger, he said. The highest dose was most common in Canada and the United States, while researchers in Latin America were the second most likely to use a high-dose aspirin regimen. The medium doses were used in Australia and New Zealand, and the lowest doses were used in Eastern and Western Europe. Among the clopidogrel-treated patients, the amount of aspirin taken daily did not significantly affect the rate at which they suffered a cardiovascular death, heart attack or stroke. Nor was there a significant difference in these outcomes among the three aspirin doses in the aspirin-only group. Conversely, "major bleeding complications increased significantly with increasing aspirin dose, both in the placebo and the clopidogrel group," Peters said. "The bleeding rate was in fact slightly lower for low-dose aspirin plus clopidogrel than for high-dose aspirin alone." In the placebo group, the bleeding risk was 1.9 percent with low-dose aspirin, 2.8 percent with medium-dose aspirin, and 3.7 with high aspirin doses. Bleeding risks for the clopidogrel patients were 3.0 percent on low-dose aspirin, 3.4 percent on medium-dose, and 4.9 percent on high-dose. Peters said lowering the dose of aspirin may substantially lessen the risk of major bleeding. "This type of evidence will certainly be very important in the development of our revised guidelines for aspirin use," said Sidney C. Smith, M.D., former chief science officer and a national spokesperson for the American Heart Association. The American Heart Association recommends aspirin for patients who've had a heart attack, unstable angina, ischemic stroke (caused by blood clot) or transient ischemic attacks (TIAs or "mini-strokes"), if not contraindicated. The association cautions that people should not start aspirin therapy without first consulting a physician. The risks and benefits of aspirin therapy vary for each person. Co-authors are S. R. Mehta, M.D.; K. A. A. Fox, M.D.; F. Zhao, M.Sc.; B. S. Lewis, M.D.; S. L. Kopecky, M.D.; R. Diaz, M.D.; P. J. Commerford, M.D.; V. Valentin, M.D.; and S. Yusuf, D. Phil.
For more information, or to contact American Heart Association, see their website at: www.americanheart.org |
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