Monitoring residual platelet activity among patients with acute coronary syndrome

Several medicines are currently used to inhibit the platelet activity. We aim to monitor the residual platelet activity (RPA) despite antiplatelet therapy and assess its relationship with major adverse events. The impedance platelet aggregation was employed to determine RPA. Totally, 202 patients with acute coronary syndrome (ACS) were followed up for 10 months for major clinical events of myocardial infarction, cerebrovascular accident (CVA), and all cause mortality, and RPA after clopidogrel loading was assessed in 30 patients. The RPA at 2 hours after 300 mg clopidogrel loading was 1 Ω (± 2.3 Ω) induced by adenosine diphosphate. Residual platelet activity of patients who experienced death, MI, or CVA was significantly higher than those who did not experience (P < .05). Cutoff values of RPA showed optimal negative predictive values (96%-97%) and poor positive predictive values (16%-29%). Therefore, RPA monitored by whole blood impedance platelet aggregation may have high exclusionary predictive value for the occurrence of major clinical events in patients with ACS.