Reasonable Duration of Clopidogrel Use After Drug-Eluting Stent Implantation in Korean Patients

Current guidelines recommend that clopidogrel be given to patients for 12 months after drug-eluting stent (DES) implantation. However, the evidence is insufficient to support the benefit of long-term clopidogrel therapy, especially in Asian patients. The aim of this study was to evaluate whether different durations of clopidogrel use might influence long-term outcomes after DES implantation. A total of 844 patients from 4 medical centers in Korea who had undergone successful DES implantation from November 2004 to April 2006 were enrolled. Patients who were event free at 6-month follow-up were divided into 2 groups by clopidogrel use (575 users, 163 nonusers) and followed. The end point was a composite of death, myocardial infarction, and stent thrombosis. During 1,056.4 patient-years of follow-up (median 2.02), there were 7 deaths, 3 myocardial infarctions, and 2 episodes of stent thrombosis. No significant differences in the primary end point were observed between clopidogrel users and nonusers (cumulative incidence 2.9% vs 2.8%, p = 0.578; adjusted hazard ratio 0.67, 95% confidence interval 0.16 to 2.77). In analysis with time-dependent covariates, the incidence rates of the primary end point during observation periods with and without clopidogrel were similar, although the effect estimates were broad (9.9 with and 10.6 without clopidogrel per 1,000 patient-years; adjusted hazard ratio 0.52, 95% confidence interval 0.09 to 3.17). Interestingly, the effect estimates from propensity score analyses, although they also had wide confidence intervals, were closer to the null than those from conventional Cox analyses. In conclusion, this cohort of Korean patients failed to show an absolute benefit of long-term clopidogrel therapy after DES implantation. The benefit of clopidogrel use beyond 6 months after DES implantation remains uncertain, and hence the decision to use long-term dual-antiplatelet therapy should be based on the risk factors of each patient.