Background and objectives The prognostic significance and optimal cutoff of HPR might differ according to a given clinical condition such as acute myocardial infarction (AMI) and ethnicity. We compared the prognostic role of high on-clopidogrel platelet reactivity (HPR) in predicting thrombotic events in a Korean population undergoing percutaneous coronary intervention (PCI) in the AMI and non-AMI setting.
Methods On-treatment platelet reactivity was measured using a VerifyNow P2Y12 assay (Accumetrics, San Diego, CA) in 1226 patients (824 males; 65짹10 years), including 413 AMI cases, 12–24 h after PCI between March 2008 and March 2010. The prevalence of cardiovascular (CV) events defined as a composite of death from CV causes, non-fatal myocardial infarction, or stent thrombosis at 1-year follow-up were compared according to HPR between patients with and without AMI.
Results The optimal cutoff for HPR 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 HPR [14 (8.8%) vs. 1 (0.4%), P<0.001] (Figure, left) whereas there was no difference in the composite endpoint based on HPR in patients without AMI [7 (2.8%) vs.8 (1.4%), p=0.193] (Figure, right).
Conclusion Increased residual platelet reactivity is related to post-discharge CV events in subjects with AMI whereas the prognostic significance of HPR seems to be attenuated in patients with stable coronary disease after PCI.