Adding Plavix to Aspirin Doesn't Help Guard Against Second Stroke: Study
WEDNESDAY Aug. 29, 2012 -- Adding the clot-busting drug Plavix to a daily dose of aspirin is no better than taking aspirin alone to prevent a second stroke in people who have had a type of stroke that is typically caused by chronic high blood pressure, a new study shows.
In fact, the combination increased the risk of gastrointestinal bleeding and death, the Canadian researchers report.
"Antiplatelet therapy is standard for the prevention of a second stroke," said study author Dr. Robert Hart, a professor of neurology at McMaster University in Hamilton, Ontario. "We wanted to see if combining two antiplatelet drugs, aspirin with clopidogrel [Plavix], would work better and prevent more strokes."
"We were disappointed that the combination of aspirin plus clopidogrel only showed a non-significant trend in reducing stroke," Hart said. "On the other side, the two together caused more bleeding and higher mortality. The higher mortality was completely unexpected."
"It is clear that the two drugs together should not be routinely used in people with lacunar stroke," he added.
Lacunar strokes occur in the small blood vessels in the brain and are most likely due to chronic high blood pressure; they account for roughly one-fifth of all strokes and are more common in blacks, Hispanics and people with diabetes.
Although lacunar strokes tend to be small, they can cause disability depending on where in the brain they occur.
The report was published in the Aug. 30 issue of the New England Journal of Medicine.
In the trial, researchers randomly assigned more than 3,000 patients who had suffered a lacunar stroke to a combination of aspirin and Plavix or aspirin and a placebo.
Patients were also randomly selected to receive aggressive blood pressure control or standard blood pressure control, the researchers noted.
Over eight years of follow-up, the rate of second strokes among those on the two drugs was 2.5 percent, compared with 2.7 percent among those taking just aspirin, they found.
Most of these second strokes were lacunar strokes, they noted. Overall, the number of second strokes in both groups was cut threefold, which was a bigger reduction than expected.
However, the rate of serious bleeding was 2.1 percent in the aspirin/Plavix group and 1.1 percent in the aspirin-only group, the researchers noted.
Moreover, there were more deaths among those taking both drugs, with 77 deaths in the aspirin group and 113 deaths in the aspirin/Plavix group, the researchers found. The reasons for the increased death rate isn't known, but is being investigated, Hart said.
In August 2011, the trial was stopped because of the results. The U.S. National Institutes of Health (NIH), which funded the study, warned at the time that there was "little likelihood of benefit in favor of aspirin plus clopidogrel [Plavix] [for] recurrent stroke should the study continue to conclusion."
The blood pressure treatment part of the trial is ongoing, and the patients have been encouraged to continue taking aspirin without Plavix, according to the NIH.
Current guidelines recommend aspirin alone, Plavix alone, or aspirin plus dipyridamole (Permole) for preventing new strokes after most types of stroke, Hart noted.
Whether a combination of Plavix and aspirin is effective in preventing other types of stroke isn't known, but is being studied, he added.
"I am a little surprised, but not shocked by this finding," said Dr. Kirk Garratt, director of interventional cardiovascular research at Lenox Hill Hospital, in New York City. "It's another disappointing finding for antiplatelet drugs. The lesson here is we shouldn't start writing prescriptions for Plavix to those patients with lacunar strokes. Practitioners have to pay attention to these negative trials."
For more on stroke, visit the American Stroke Association.
Posted: August 2012
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