Abstract W P114: Assessment of Platelet Thrombus Formation in Patients with Carotid Disease Administered Clopidogrel

Background: Many studies have demonstrated that high residual platelet function in patients administered clopidogrel is associated with cardiovascular events, although, the majority of those studies examined the patients with coronary artery disease. We studied platelet function in patients with ischemic stroke treated by clopidogrel, and compared residual platelet function according to the severity of carotid disease. Methods: We measured platelet aggregation induced by ADP, VerifyNow P2Y12 assay (PRU), phosphorylation of vasodilator-stimulated phosphoprotein (PRI), platelet-leukocyte complex (PLC), and platelet p-selectin expression (PS) in 30 patients with ischemic stroke administered clopidogrel (21 males and 9 females, mean age was 65 years). We also measured platelet thrombus formation under arterial flow conditions using newly developed microchip-based flow chamber system. In this system, platelet thrombus formation was analyzed by measuring flow pressure changes due to occlusion of microchip and was quantified by calculating area under the flow pressure curve (AUC). Each marker was compared between patients with severe carotid stenosis (15 cases) and those with mild to moderate carotid stenosis (15 cases). Results: Platelet function tests such as percentages of platelet aggregation induced by ADP, PRU, PRI, and PS was not significantly different between different severities of carotid stenosis. On the other hand, AUC values and PLC of patients with severe major carotid stenosis were significantly higher than those with mild to moderate stenosis. Conclusions: These results suggested that clopidogrel inhibits platelet aggregation irrespective of the severity of carotid stenosis. On the other hand, platelet thrombus formation under arterial flow conditions and platelet leukocyte interactions were higher in patients with severe carotid stenosis than those with mild to moderate stenosis.