Post-Treatment Platelet Reactivity Predicts Long-Term Adverse Events Better Than the Response to Clopidogrel in Patients With Non-ST-Segment Elevation Acute Coronary Syndrome

Abstract

Poor response to antiplatelet therapy has been associated with adverse long-term outcomes. The objective of this study is to assess the relationship between response to clopidogrel and post-treatment platelet reactivity (PPR) and 1-year major adverse cardiovascular events (MACE) in patients with non-ST segment elevation acute coronary syndrome (NSTEACS). Patients with NSTEACS undergoing early coronary angiography were enrolled in this prospective, observational study. The VerifyNow analyzer was used to measure clopidogrel response and PPR immediately before coronary angiography. Of the 179 patients included (97 percutaneous coronary intervention, 21 coronary artery bypass graft), 161 (90%) completed 1-year follow-up and 18 (11%) incurred MACE: 10 deaths, 6 myocardial infarctions, 2 strokes, 5 revascularizations. Lower response to clopidogrel (31 +/- 21% vs. 43 +/- 21%; P.049) and higher PPR (204 +/- 60 vs. 155 +/- 67 platelet reaction units [PRU]; p= 0.006) were significantly associated with MACE occurrence. Multivariate analysis confirmed PPR (OR per 10-unit increase: 1.12, 95%CI: 1.01-1.24; P.020) as an independent predictor of MACE. A PPR cut-off value of 175 PRU was associated with an adjusted OR for 1-year MACE occurrence of 3.9 (95%CI: 1.2-15.4; P.024). PPR predicts adverse long-term outcomes better than response to clopidogrel in patients with NSTEACS. Patients with PPR values above 175 PRU were identified as being at higher risk for adverse long-term events.