Clopidogrel Response Variability and Its Correlation with Early Recurrent Cardiovascular Events in Chinese Patients Undergoing Percutaneous Coronary Intervention

Abstract

Background/Aims:Numerous studies conducted on Caucasian patients have reported that individual responsiveness to clopidogrel varies widely, whereas there are only a few published studies on the antiplatelet effect of clopidogrel therapy in Chinese patients undergoing percutaneous coronary intervention. The present study aimed to evaluate clopidogrel antiplatelet effects and their correlation with early recurrent cardiovascular (CV) events. Methods: Platelet aggregation (with 5 and 20 µmol/l ADP) and the expression of glycoprotein Ib and P-selectin were measured at baseline and 12 and 36 h after the clopidogrel loading dose in 111 consecutive patients. The primary outcome was a definite CV event. Results: There was marked interindividual variability in the drug response, as measured by platelet aggregation and P-selectin expression. The proportions of nonresponders at 12 and 36 h were 32 and 19%, respectively, with 5 µmol/l ADP, 38 and 28% with 20 µmol/l ADP, and 27 and 17% according to P-selectin expression. The maximal aggregation rates stimulated by 5 µmol/l ADP in nonresponders were significantly higher than those of the responders at 12 h (57.53 ± 14.24% vs. 33.91 ± 10.79%; p < 0.0001) and at 36 h (48.65 ± 15.46% vs. 30.31 ± 16.04%; p < 0.0001). During the 3-month follow-up period, 11 patients (32.4%) among the nonresponders, 2 patients (7.1%) among the low responders and none of the responders suffered a recurrent CV event (p < 0.0001). Conclusions: The antiplatelet effectiveness of clopidogrel has a wide interindividual variation, and nonresponsiveness to clopidogrel is associated with an increased risk of early recurrent CV events.