High Residual Platelet Reactivity After Clopidogrel Loading and Long-Term Clinical Outcome After Drug-Eluting Stenting for Unprotected Left Main Coronary Disease

Abstract

Background— No data exist about the impact of high residual platelet reactivity (HRPR) after clopidogrel loading on long-term clinical outcome in patients undergoing drug-eluting stent (DES) implantation for unprotected left main disease (ULMD). Methods and Results— Consecutive patients who underwent percutaneous coronary intervention for ULMD had prospective platelet reactivity assessment by light transmittance aggregometry after a loading dose of 600 mg of clopidogrel. The primary end point of the study was cardiac mortality, and the secondary end point was stent thrombosis. From January 2005 to September 2008, 215 consecutive patients were treated with DES for ULMD. The incidence of HRPR after clopidogrel loading was 18.6%. The median follow-up was 19.3 months. The overall estimated 1-, 2- and 3-year cardiac mortality rate was 3.9±1.3%, 7.5±2.2%, and 12.2±3.4%, respectively. The 3-year cardiac mortality rate was 8.0±3.1% in the low residual platelet reactivity (LRPR) group and 28.3±10.4% in the HRPR group ( P =0.005). The 3-year stent thrombosis rate was 4.2±1.8% in the low residual platelet reactivity group and 16.0±7.3% in the HRPR group ( P =0.021). By forward stepwise regression analysis, HRPR after clopidogrel loading was the only independent predictor of cardiac death (hazard ratio, 3.82; 95% confidence interval,1.38 to 10.54; P =0.010) and stent thrombosis (hazard ratio, 3.69; 95% confidence interval, 1.12 to 12.09; P =0.031). Conclusions— HRPR after 600-mg clopidogrel loading is a strong marker of increased risk of cardiac death and DES thrombosis in patients receiving DES stenting for ULMD. Routine assessment of in vitro residual platelet reactivity after clopidogrel loading in patients with ULMD potentially suitable for DES-supported percutaneous coronary intervention should be considered to guide patient care decisions.