Higher Aspirin Doses May Protect Recurrent Strokes
January 28th, 2008 | 
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Vadim Karepov, M.D., Ph.D., and his colleagues at the Tel Aviv Medical Center in Israel, examined the patient profiles of 3,140 consecutive stroke patients, 2,239 of whom had a first ischemic stroke, and 901 of whom had experienced a second ischemic stroke. They found that aspirin failed to act in 126 of the 2,239 with a first stroke and 157 of the 901 with a second stroke. Aspirin doses in these patients ranged from 100 to 1,000 milligrams (mg) daily.
An ischemic stroke is one caused by a reduction or cessation of blood flow, usually resulting from a clot that plugs up an artery that feeds blood to the brain.
The researchers found that individuals who have hyperlipidemia (elevated cholesterol and other lipids) were most prone to aspirin failure and might benefit from higher doses than typically used (aspirin doses usually range from 125 - 1,000 mg daily).
Karepov presented these results today at the AHA’s 21st International Joint Conference on Stroke and Cerebral Circulation.
“Our results show a possible way of preventing a second stroke in these patients who will require higher doses or other aggressive therapy,” says Karepov, noting that the effectiveness of aspirin increased with doses of 350 mg/day or more. Aggressive therapy in such cases could include such actions as: higher aspirin doses; use of the drug Ticlid (which keeps platelets — blood- clotting components — from sticking together); treatment with anticoagulants; and combination drug therapy, Karepov says.
Cathy Helgason, M.D., professor of neurology at the University of Illinois College of Medicine in Chicago, comments that the Tel Aviv study’s results were consistent with other research showing that aspirin is effective in preventing stroke recurrence in some, but not all, stroke survivors.
“It provides another piece of the puzzle as to why some people fail with aspirin,” says Helgason. “It suggests that some are not taking the right doses and that there might be a particular dose for a particular person.”
Karepov is one of a team of researchers involved in the Tel Aviv Stroke Study, a project focusing on stroke prevention
In the study Karepov explored causes of aspirin failure, including age, ischemic heart disease, cholesterol and lipid levels and inadequate aspirin dose. The 3,140 men and women who participated in the trial were grouped according to whether they had had one or more strokes and if they had taken aspirin regularly as a preventive treatment
Hyperlipidemia and aspirin dose were the only striking links to aspirin failure. Among patients who had suffered a single stroke, hyperlipidemia was associated with aspirin failure in 23 percent of cases. Hyperlipidemia was present in only 7.8 percent of patients who responded to aspirin.
Similar trends were found among patients with recurrent strokes. Hyperlipidemia was observed in 14 percent of the aspirin-failed group versus 6.4 percent of those whom aspirin did not fail.
“We have seen that aspirin prevents mortality and severity of recurrent strokes, but it is less effective in patients with such ischemic heart disease risk factors as hyperlipidemia. These patients need more aggressive therapy or bigger doses,” concludes Karepov.
Although aspirin has been used for about 15 years as preventive therapy against second strokes, it averts only about 25 percent of recurrent strokes. Aspirin also has not been shown effective against first strokes, according to Karepov.
Stroke is the third leading cause of death and the leading cause of serious disability in the United States.
By: Onuri Tun
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Posted in Critical Care