Diversity Of Platelet Activation After Clopidogrel Intake In Patients With Cardiovascular Disease

Dual antiplatelet treatment with aspirin and clopidogrel is a main and widely used therapy on patients with cardiovascular disease for preventing thrombosis of treated vessels and subsequent ischemic events. However, great individual variabilitis including aspirin resistance and stenting thrombosis can be found among patients treated. No sensitive and specific assay is available to screen any dysfunction in platelet adhesion, aggregation, activation and secretion. Although there is always no clear indication, several tests are necessary to evaluate platelet function. Factors from genetic polymorphism, cellular and methodology were considered in this study. Blood concentration of clopidogrel was measure with LC-MS/MS to verify the relation between drug concentration and polymorphism. Major tools such as platelet aggregation, inhibition on Thrombelastography, platelet memberane activating marker-CD62p and vasodilator sitmulated phosphoprotein (VASP) were applied to evaluated platelet function on different time point at baseline,10h and 36h after 300mg loading dose.CYP2C19*2 (681G>A) and*3 (636G>A) were genotyped with High Resolution Melting, only one*2 mutation and no*3 were found. Subject with mutation is different with wild individuals on several parameters like ADP induced aggregation. Although both wild and mutation subject(s) were inhibited at 10h after 300mg loading dose, no further time depended effect was found in the mutation. In addition, it showed not only slow drug metabolism, but also decreasing inhibition. Therefore, dividing 600mg loading dose into two days may not achieve enough inhibition.Genetic screening of risk factors have not become clinical routine test, however, polymorphism is important to recurrent of cardiovascular events in certain individual. Thus, screening of major functional mutation will lead to determination of reference range and optimization of therapy. Lack of criteria on platelet function analysis will lead to aberration judgement of platelet reaction, even clinical desicition. Platelet inhibition based on Thrombelastography improves reproducibility and standardization much more than aggregation, but the change of parameter is different from the latter. VASP phosphrilation could reflect inhibition of P2Y12 receptor secificly, no relation can be found between VASP and CD62p. As to monitoring on antiplatelet therapy, it is important to choose assays according drug intake, correlation analysis may not feasible to all method for different principle, even lead to wrong decision.