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.