Different Prognostic Significance of High On-Treatment Platelet Reactivity as Assessed by the VerifyNow P2Y12 Assay After Coronary Stenting in Patients With and Without Acute Myocardial Infarction

ObjectivesThis study compared the prognostic role of high on-treatment platelet reactivity (HTPR) in predicting thrombotic events in a Korean population undergoing percutaneous coronary intervention (PCI) in the acute myocardial infarction (AMI) and non-AMI setting.BackgroundThe prognostic significance and optimal cutoff of HTPR might differ according to a given clinical condition, such as AMI and ethnicity.MethodsOn-treatment platelet reactivity was measured with a VerifyNow P2Y12 assay (Accumetrics, San Diego, California) in 1,226 patients (824 men; age 65 ± 10 years), including 413 AMI cases, 12 to 24 h after PCI between March 2008 and March 2010. The prevalence of cardiovascular (CV) events defined as a composite of death from CV causes, nonfatal myocardial infarction, or stent thrombosis at 1-year follow-up were compared according to HTPR between patients with and without AMI.ResultsThe optimal cutoff for HTPR was 272 IU of the P2Y12 reaction unit (PRU) (area under the curve: 0.708; 95% confidence interval [CI]: 0.607 to 0.809, p = 0.03), which was the upper-tertile threshold. Among AMI patients, 1-year CV events occurred more frequently in patients with versus without HTPR (n = 14 [8.8%] vs. n = 1 [0.4%], p < 0.001), whereas there was no difference in the composite endpoint on the basis of HTPR in patients without AMI (n = 7 [2.8%] vs. n = 8 [1.4%], p = 0.193).ConclusionsIncreased residual platelet reactivity is related to post-discharge CV events in subjects with AMI, whereas the prognostic significance of HTPR seems to be attenuated in patients with stable coronary disease after PCI.