Antiplatelet therapy is used for both the management of acute ischemic stroke and for the prevention of stroke. Antiplatelet therapy reduces the incidence of stroke in patients at high risk for atherosclerosis and in those with known symptomatic cerebrovascular disease.
Antiplatelet therapy for secondary stroke prevention will be reviewed here. Antiplatelet therapy for acute ischemic stroke and for primary stroke prevention is discussed separately. (See "Antithrombotic treatment of acute ischemic stroke and transient ischemic attack" and "Overview of primary prevention of coronary heart disease and stroke".)
Prevention of recurrent stroke with antithrombotic therapy in patients with atrial fibrillation is reviewed elsewhere. (See "Atrial fibrillation: Anticoagulant therapy to prevent embolization".)
Aspirin, the most commonly used antiplatelet agent, inhibits the enzyme cyclooxygenase, reducing production of thromboxane A2, a stimulator of platelet aggregation. This interferes with the formation of thrombi, thereby reducing the risk of stroke. (See "Benefits and risks of aspirin in secondary and primary prevention of cardiovascular disease".)
The effectiveness of aspirin for preventing ischemic stroke and cardiovascular events is supported by a meta-analysis from the Antithrombotic Trialists Collaboration (ATC) published in 2002 . The ATC analyzed 195 randomized controlled trials comparing antiplatelet therapy, primarily aspirin, with placebo in the prevention of stroke, myocardial infarction (MI), and vascular death among high-risk patients with some vascular disease or other condition implying an increased risk of occlusive vascular disease. Patients treated with an antiplatelet agent (primarily aspirin) had a 25 percent relative risk reduction in nonfatal stroke compared with placebo.