Prolonged Clopidogrel Use is Associated with Improved Clinical Outcomes Following Drug-Eluting But Not Bare Metal Stent Implantation

Background Guidelines recommend clopidogrel use for 6–12 months following drug-eluting stent (DES) implantation and 1–12 months following bare metal stent (BMS) implantation. The role of clopidogrel beyond 12 months is unclear. Methods We linked hospital administrative, community pharmacy and cardiac revascularization data to determine clopidogrel use and outcomes for all patients (those with acute presentations and those with stable angina) receiving a coronary stent in British Columbia 2004–2006, with follow-up until the end of 2008. Cox proportional hazard regression was performed to evaluate the effect of clopidogrel duration (≤12 vs. >12 months) on outcomes following BMS or DES implantation. Patients who died ≤12 months from index stent placement were excluded. Results A total of 15,629 patients were included in the study. Of 3599 patients who received at least one DES and 12,030 patients who received only BMS, 1326 (37 %) and 2121 (18 %), respectively, filled a prescription for clopidogrel >12 months from the index procedure. The mean duration of clopidogrel was 406 ± 35 days and 407 ± 37 days in the prolonged use (>12 months) DES and BMS cohorts, respectively, compared with 224 ± 112 days ( p < 0.001) and 122 ± 117 days ( p < 0.001), respectively, for patients receiving clopidogrel ≤12 months. Clopidogrel use beyond 12 months was associated with a reduction in mortality [hazard ratio (HR) 0.66, 95 % confidence interval (CI) 0.45–0.97] and the composite of mortality and readmission for myocardial infarction (HR 0.72, 95 % CI 0.55–0.94) in patients treated with DES, but not BMS alone. Prolonged clopidogrel use was not associated with bleeding-related mortality. Conclusions Clopidogrel use beyond 12 months was associated with a reduction in death and hospitalization for myocardial infarction following DES, but not BMS, implantation. Our findings support a longer duration of clopidogrel therapy for patients treated with DES.