Antiplatelet therapy for prevention of recurrent stroke

Stroke is a common public health problem. About 25% of strokes are recurrent ones. Stroke subtype should be defined to determine the best evidence-based antithrombotic treatment option for preventing recurrent stroke. When choosing an antiplatelet agent for this purpose, clinicians should take into account cost, side effect profile, medical comorbidity, and patient preference. To prevent recurrent stroke, aspirin alone (50-325 mg/d), a combination of aspirin (25 mg) plus extended-release dipyridamole (200 mg), given twice daily, or clopidogrel (75 mg/d) may be used as initial treatment. Aspirin is an efficacious, relatively safe, widely available, inexpensive, and easy-to-use antiplatelet agent. Current evidence suggests that administration of low-dose aspirin (< 325 mg/d or < 100 mg/d in various studies) is at least as efficacious as higher-dose aspirin (eg, > 325 mg/d) but is safer. The combination of aspirin plus extended-release dipyridamole is more efficacious than low-dose aspirin alone (eg, 50 or 75 mg/d) in preventing recurrent stroke. Clopidogrel (75 mg/d) may be more efficacious than aspirin alone (325 mg/d) for prevention of recurrent stroke. Clopidogrel is a prodrug that must be converted in the liver to its active metabolite by cytochrome P450 enzymes. Certain polymorphisms (eg, CYP2C19) may prevent this conversion and lead to failure of clopidogrel to prevent major cardiovascular events. In patients with well-controlled or treated cardiovascular risk factors, aspirin plus extended-release dipyridamole and clopidogrel may provide similar results in preventing recurrent stroke, but aspirin plus extended-release dipyridamole may be associated with a slightly higher risk of major hemorrhage. Careful control of vascular risk factors is an important strategy for prevention of recurrent stroke, and blood pressure control reduces the risk of both brain hemorrhage and infarction. Prasugrel, a new thienopyridine derivative, more quickly and consistently inhibits platelets than clopidogrel. In stroke patients, prasugrel may be associated with a higher risk of brain hemorrhage, so it may not be indicated when there is a history of cerebrovascular disease.