The predictive value of mean platelet volume for clopidogrel responsiveness in patients who use clopidogrel for acute coronary sydrome and percutaneous coronary artery intervention

Background: Clopidogrel therapy is the standard of care in patients with acute coronary syndrome (ACS) and stent implantation. However, concern arises because 25 % of subjects are nonresponders to clopidogrel. As this nonresponsiveness is associated with increased adverse outcome, detection of these subjects in daily practice is important in order to withhold a more aggressive therapy and closer follow up. In this study we aimed to evaluate the relation between mean platelet volume (MPV) which is an indicator of platelet activation and clopidogrel nonresponsiveness.Methods: A total of 217 patients who had been on clopidogrel therapy for any indication were enrolled in this study. Of these 217 cases, the diagnosis was STEMI in 56,2%, NSTEMI in 17,5%, stable angina pectoris (SAP) in 14,3% and unstable angina pectoris in 11,5%. Clopidogrel responsiveness was analyzed by Multiplate MP-0120 device by using the method of whole blood aggregometry. Blood samples were drawn 3,5 days after clopidogrel loading dose. The amount of ADP induced platelet aggregation was assessed as area under curve (AUC), and a cut off value of 500, above which the patient is considered as clopidogrel nonresponder, was used. MPV was analyzed from the blood which were sampled at the admission of the patient by using automatic hemocounter.Results: Among the 217 patients analyzed 45 were found to be clopidogrel nonresponder (%20,7). Mean MPV was found to be significantly higher in nonresponders compared to responders (8.651 vs. 8,163 p<0,001). When the patients were classified as stable angina (n=32) and ACS (n=185), although there was no association in SAP group (8,0 vs 8,3 p=0,5), MPV was significantly higher in nonresponders among ACS patients (8,7 vs 8,1 p<0,001). A cut of value of 8,4fl for MPV was detected in prediction of clopidogrel nonresponsiveness with a sensitivity of 66% and specificity of 68%.Conclusion: This study showed that high MPV values are associated with clopidogrel nonresponsiveness especially in patients with ACS.