Antiplatelet drugs for ischemic stroke prevention.

In primary prevention trials conducted in low-risk subjects, aspirin is associated with a small reduction in ischemic strokes in women. It also reduces the incidence of stroke in patients with nonvalvular atrial fibrillation (NVAF), but warfarin is more effective in patients with high blood pressure, or left ventricular dysfunction, especially those aged >75 years. According to secondary prevention trials in patients after noncardioembolic ischemic stroke or transient ischemic attacks, aspirin at any dose between 50 and 1,300 mg per day reduces the risk of new events, but doses >150 mg per day are associated with a worse gastrointestinal tolerance. Clopidogrel and a combination of aspirin plus extended-release dipyridamole are both slightly more effective than aspirin, but the combination of aspirin and clopidogrel does not reduce the risk of new vascular events and increases life-threatening bleedings. Aspirin cannot be recommended for secondary prevention in NVAF, except in the case of absolute contraindications to warfarin. The available data show that at the acute stage of ischemic stroke, aspirin is safe and slightly more effective than placebo or heparin, even in NVAF, but other antiplatelet agents have not been evaluated.