Previous clinical trials have shown that anti-platelet drugs, such as aspirin and ticlopidine, are approved for prevention of serious cardiovascular events in special populations who are at increased risk of cardiovascular events. Of these trials, the Antithrombotic Trialists' Collaboration (ATT) meta-analysis includes approximately 200,000 patients: Anti-platelet therapy was associated with a 34% reduction in the risk of nonfatal myocardial infarction, a 25% reduction in the risk of stroke, and a 15% reduction in the risk of vascular death. Also in patients with acute coronary syndrome (acute myocardial infarction and unstable angina), both aspirin and ticlopidine have been shown to prevent serious cardiovascular events.