Serial change in platelet activation markers with aspirin and clopidogrel after acute ischemic stroke.

Objectives: Antiplatelet drugs are widely used for secondary prevention after cerebral ischemia of noncardioembolic origin and different anfiplatelet drugs exert different pharmacologic effects. This study investigated differences in platelet activation markers in patients taking either aspirin or clopidogrel after acute ischemic stroke. Methods: A prospective randomized case-control study evaluated 70 patients with noncardioembolic stroke treated with either aspirin (100 mg/d) or clopidogrel (75 mg/d) after acute ischemic stroke. Platelet activation markers (CD62P, CD63, and CD40L) were measured by flow cytometry at different time points (<48 hours and days 7, 30, and 90 after stroke). The markers were also evaluated in 30 at-risk control subjects. Results: Ischemic stroke patients had significantly increased circulating CD62P, CD63, and CD40L in the acute stage compared with the control group. Levels of CD62P, CD63, and CD40L were more significantly reduced in the clopidogrel group than in the aspirin group in the first week after stroke. Furthermore, differences in CD62P and CD63 levels were significant even at 1 month after stroke. Conclusions: Patients treated with clopidogrel have lower platelet activity than those taking aspirin after acute ischemic stroke. The stronger effect of clopidogrel is notable 1 week after stroke and persists for at least 1 month. Further large-scale trials are warranted to clarify optimal treatment.