Monitoring Residual Platelet Activity Among Patients With Acute Coronary Syndrome Post-PCI by Modified Impedance Whole Blood Platelet Aggregation and Release Method

Antiplatelet medicines have been one of the cornerstones in the treatment of patients with acute coronary syndrome (ACS). However, adverse cardiovascular events still occur in some patients on standard antiplatelet therapy. Therefore, a reliable laboratory test to monitor the residual platelet activity (RPA) is urgent. We aim to modify the impedance whole blood platelet aggregation (WBA) assay associated with release assay to monitor RPA, despite antiplatelet therapy and assess their relationship with clinical ischemic events. In this study, RPA was tested in 133 patients with ACS postpercutaneous coronary intervention between 24 and 36 hours after a 300-mg clopidogrel loading dose by modified assay. Then, these patients were followed up for 3 months for clinical ischemic events. Meanwhile, platelet activity of 58 healthy volunteers was also tested by modified assay. Results showed that in modified assay the point of platelet magnified activation time (MAT) and maximal platelet adenosine triphosphate release values (RV) have significant differences between healthy volunteers and patients ([90.86 ± 27.60 seconds] vs [206.44 ± 58.97 seconds] and [2.07 ± 0.64 nmol] vs [0.98 ± 0.49 nmol];P< .001 andP< .001, respectively). During follow-up, 5 patients present ischemic events. Receiver-operator characteristic curve showed that the cutoff values for MAT and RV were 156.5 seconds and 1.05 nmol, respectively, with the sensitivity and specificity of 60.00% and 83.30% and 80.00% and 67.50%, respectively; when MAT combined with RV, the sensitivity can be increased to 100%. Therefore, modified impedance WBA and release assay may be a potentially recommended reliable laboratory assays for monitoring the RPA.