Both high and low platelet responses to clopidogrel are highly associated with mortality. A therapeutic window for platelet reactivity was recently determined to be an important factor for improving clinical outcomes after percutaneous coronary intervention (PCI). We evaluated the impact of the antiplatelet activity of clopidogrel on long-term clinical outcomes in Korean patients receiving PCI. We analyzed the clinical outcomes of 814 Korean patients undergoing PCI for a median of 48 months. Platelet reactivity on clopidogrel was measured with the VerifyNow P2Y12 assay. The primary endpoint was all-cause death at 4 years. Patients were classified into three groups according to the P2Y12 reaction unit (PRU): low platelet reactivity (LPR; PRU < 85), normal platelet reactivity (NPR; 85 ≤ PRU < 208), and high platelet reactivity (HPR; PRU ≥ 208). The incidence of all-cause death was 7.0% in the LPR group, 1.5% in the NPR group, and 6.2% in the HPR group (log-rank p = 0.002). Based on multivariate analyses, all-cause death was significantly higher in both the LPR and HPR groups than in the NPR group (LPR, hazard ratio [HR]: 5.095; 95% confidence interval [95% CI]: 1.360-19.080, p = 0.016; HPR, HR: 3.315; 95% CI: 1.145-9.593, p = 0.027). Both LPR and HPR were significantly associated with long-term mortality in Korean patients receiving PCI, which suggests that the therapeutic concept of PRU may be an important prognostic factor.
Keywords: Clinical outcomes; P2Y reaction unit; clopidogrel; therapeutic window.