Comparison of 2 point-of-care platelet function tests, VerifyNow Assay and Multiple Electrode Platelet Aggregometry, for predicting early clinical outcomes in patients undergoing percutaneous coronary intervention

Background: Various platelet function tests are currently used to measure responsiveness to antiplatelet therapy. We sought to compare 2 point-of-care platelet function tests, VerifyNow Assay (Accumetrics, San Diego, CA) and Multiple Electrode Platelet Aggregometry (MEA) (Dynabyte, Munich, Germany), for predicting early clinical outcomes after percutaneous coronary intervention. Methods: Platelet reactivity in the arachidonic acid-induced and adenosine diphosphate (ADP)-induced platelet aggregation was measured simultaneously with the VerifyNow Assay and MEA in 222 patients undergoing percutaneous coronary intervention between August and October 2009. We investigated the correlations between the 2 tests and performed receiver operating characteristic curve analysis for major adverse cardiovascular events (MACE), a composite of death, myocardial infarction (MI), stroke, and target vessel revascularization, at 30 days. Results: Major adverse cardiovascular events occurred in 19 patients (8.6%), including 14 patients with periprocedural MI and 5 patients with stroke. Correlations were weak between the 2 tests in the arachidonic acid-induced (Spearman r = 0.189, P = .006) and ADP-induced platelet reactivity (Spearman r = 0.390, P < .001). Although the VerifyNow P2Y12 Assay (Accumetrics) was able to predict periprocedural MI (area under the aggregation curve 0.680, P = .024) and 30-day MACE (area under the aggregation curve 0.649, P = .032), VerifyNow Aspirin Assay (Accumetrics), MEA ASPI test, and MEA ADP test failed to predict such clinical events. Hyporesponsiveness to clopidogrel based on the VerifyNow Assay was associated with about a 6-fold increased risk of MACE at 30 days. Conclusions: Hyporesponsiveness to clopidogrel measured by VerifyNow Assay was able to identify patients with dual antiplatelet therapy who were at higher risk for periprocedural MI and MACE at 30 days. Further randomized studies are required to validate the effectiveness of different platelet function tests for predicting long-term clinical outcomes.