NIH News Release
National Institute of
Neurological Disorders and Stroke

Thursday, June 24, 1999
6:00 p.m. EST

Contact: Marcia Vital
(301) 496-5751

Low Doses of Aspirin and Surgery Better for Stroke Prevention

A new study shows that lower doses of aspirin given at the time of surgery work better than higher doses to prevent strokes. The Aspirin and Carotid Endarterectomy (ACE) trial, sponsored by the National Institute of Neurological Disorders and Stroke (NINDS), found that patients given 81 or 325 mg of aspirin a day for three days before and 3 months after carotid endarterectomy (CE) surgery had less risk of stroke, heart attack, or death 30 days and 3 months following the surgery than did patients given 650 or 1300 mg a day. The study will appear in the June 26, 1999, issue of the journal The Lancet1.

"While a great deal of research has established that aspirin reduces the risk of stroke in certain patients, the amount of aspirin required was not clear," says Wayne D. Taylor, M.A., a professor in the Department of Clinical Epidemiology and Biostatistics at McMaster University in Hamilton, Ontario, Canada, and lead author of the study. "This study has answered the dose question for patients who will receive carotid endarterectomy surgery."

While the results of The Lancet study are strong, the investigators warn against overgeneralizing the benefits of low-dose aspirin for stroke prevention. The amount of aspirin required to prevent stroke in the 30 days after surgery may differ from the amount of aspirin that may be taken for years to prevent strokes in the longer-term medical management of high-risk stroke patients.

"This trial demonstrates that lower doses of aspirin work well," says John R. Marler, M.D., a neurologist and program officer at the NINDS. "This is good news because lower doses are easier to take and better tolerated, so more people can get the full benefit of aspirin."

The ACE trial is the first randomized clinical trial to determine the best dose of aspirin for stroke prevention following CE surgery. The medical community first became aware of aspirin's protective effects for stroke in 1978, and, since then, several large clinical trials have shown that aspirin reduces the risk of stroke. The ACE trial resulted from the observation that aspirin seemed to decrease the risk of stroke following CE surgery in the North American Stroke and Carotid Endarterectomy Trial (NASCET).

For more information about the NASCET study and carotid endarterectomy, visit the NINDS stroke information web page at

The NINDS is the nation's premier supporter of research on the brain and nervous system. It is part of the National Institutes of Health in Bethesda, Maryland, and will celebrate its 50th anniversary in the year 2000.

This release will be posted on EurekAlert! at and on the NINDS home page at

1Taylor, W.D.; Barnett, H.J.M.; Haynes, B.R.; Ferguson, G.G.; Sackett, D.L.; Thorpe, K.E.; Simard, D.; Silver, F.L.; Hachinski, V.; Clagett, G.P.; Barnes, R.; Spence, J.D. for the ASA and Carotid Endarterectomy (ACE) Trial Collaborators. "A randomized trial of low and high dose aspirin for patients undergoing carotid endarterectomy." The Lancet, Vol. 353, No. 9171, June 26, 1999, pp. 2179-2184.