Antiplatelet therapy and risk of stroke.

Antiplatelet therapy, especially with aspirin, reduces the risks of occlusive vascular disease, including ischemic stroke. In an overview of 25 trials of antiplatelet therapy in patients with prior cardiovascular disease, antiplatelet treatment reduced subsequent nonfatal stroke by 27% (P = 0.0001), nonfatal myocardial infarction by 32% (P = 0.0001), and all vascular deaths by 15% (P = 0.0003), with no evidence that other antiplatelet agents were more effective than aspirin, or that higher aspirin doses (900 to 1500 mg daily) were more effective than 300 mg, the lowest daily dose tested. If begun during the acute phase of myocardial infarction, aspirin reduces nonfatal stroke by 46% (P < 0.01) and vascular deaths by 23% (P < 0.00001) after 5 weeks. In primary prevention, currently available data are inconclusive regarding the effect of aspirin therapy on stroke. However, any potential benefit on ischemic stroke must be weighed against the possibility that aspirin could increase the risk of the less common, but clinically more severe, strokes of hemorrhagic etiology.