Prevention of vascular events in patients with cerebrovascular disease: efficacy and appropriate duration of antiplatelet therapy.

Antiplatelet therapy has shown consistent benefit in the prevention of secondary stroke. The paucity of head-to-head studies of different antiplatelet regimens, assessment of comparative efficacy, and optimal treatment duration requires evaluation and comparison of clinical studies that vary extensively in design and follow-up. Evidence for aspirin benefit in secondary stroke prevention is strong, but existing studies provide little guidance with regard to treatment duration. The efficacy of clopidogrel in secondary event prevention is significantly greater than that of aspirin for patients with a history of peripheral artery disease, but does not differ from that of aspirin for patients with a history of stroke or myocardial infarction. Relative to clopidogrel alone, the addition of aspirin to clopidogrel results in increased risk for life-threatening bleeding episodes similar in absolute magnitude to the reduction of secondary event risk in patients with stroke. Benefits associated with clopidogrel occur early in the course of therapy; few data support clopidogrel use for longer than 1 year after stroke. Monotherapy with extended-release dipyridamole (ER-DP) provides reduction in secondary stroke risk similar to aspirin; however, the combination of aspirin plus ER-DP significantly reduces risk relative to either agent alone. Compared with placebo and monotherapy with either agent, risk reduction for the aspirin plus ER-DP combination continued through 24 months, with no concomitant increase in bleeding risk. Additional clinical studies should provide needed comparisons of efficacy and guidance with regard to optimal duration of therapy.