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By November 1989,1244 patients had been followed for a mean of 1.13 years. The event rates were 1.6 percent per year in the 393 patients who made up the two active treatment arms(warfarin and aspirin)of group 1,and 8.3 percent per year in the 195 patients who made up the placebo arm(P<0. 00005)(risk reduction,81 percent;95 percent confidence interval,56 to 91). In all 517 patients given aspirin,the rate of primary events(3.2 percent per year)was lower than that in the 528 patients given placebo(6.3 percent per year;P=0.014)(risk reduction,49 percent;95 percent confidence interval,15 to 69).However,we were unable to show a benefit of aspirin in patients over 75 years of age.These preliminary data indicate that antithrombotic therapy with warfarin or aspirin is effective in the short term in reducing the risk of stroke and systemic embolism in patients with atrial fibrillation due to causes other than rheumatic valvular disease. The relative benefits of aspirin and warfarin remain unclear,and the trial is continuing in order to address this issue. |
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