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Aspirin Shown Equal to Warfarin for Stroke Prevention in Some Patients


For release: Thursday, March 17, 1994

Results from a new study, funded by the National Institute of Neurological Disorders and Stroke (NINDS), will help physicians select optimum treatment to prevent stroke in people with atrial fibrillation, a common type of irregular heartbeat. Published in the March 19, 1994 issue of The Lancet *, the study shows that a daily adult aspirin can provide adequate stroke prevention for many of the hundreds of thousands of people with atrial fibrillation. People with this condition have five times the risk of stroke, and many are currently treated with warfarin, a drug that requires monthly blood tests and increases the risk of serious bleeding.

In a study of 1,100 men and women at 18 U.S. medical centers, the investigators compared treatment with a single daily adult aspirin, which reduces the clumping of blood cells called platelets, to treatment with warfarin, which reduces the blood's ability to clot. When routinely used, warfarin is monitored by blood tests and dosage adjustments. For most people with atrial fibrillation under 75 years old, and for those over 75 with no additional stroke risk factors such as high blood pressure or heart disease, aspirin provided adequate protection with minimal complications. The study was coordinated by Robert G. Hart, M.D., and David G. Sherman, M.D., of the University of Texas Health Sciences Center at San Antonio.

"Four years ago we showed that we could cut the risk of stroke 50 to 80 percent by giving either aspirin or warfarin to people with atrial fibrillation," said Patricia A. Grady, Ph.D., acting director of NINDS. "But we left many with the difficult choice between the two. Now we have good news. Doctors can more confidently offer a specific group of patients a therapy that prevents stroke, is less expensive, and has fewer side effects."

Atrial fibrillation occurs in 1.5 million Americans and has been associated with about 75,000 strokes each year. In this condition, the two upper chambers of the heart lack their rhythmic, forceful beat, and the pulse is irregular. This can slow blood flow, allowing clots to form. Stroke occurs if one of these clots becomes stuck in an artery and cuts off blood flow to parts of the brain. The resulting brain injury may be manifest as paralysis, weakness or loss of speech.

The NINDS, one of the National Institutes of Health located in Bethesda, MD, is the nation's principal sponsor of research on the brain and nervous system. The Institute is a lead agency for the Congressionally mandated Decade of the Brain.

*Stroke Prevention in Atrial Fibrillation Investigators. 1994. "Warfarin versus aspirin for prevention of thromboembolism in atrial fibrillation: the Stroke Prevention in Atrial Fibrillation II Study." The Lancet, Vol. 343, No. 8899, pp. 687-691.

Last Modified August 7, 2009