Abstract 4479: Antiplatelet Therapy and Stent Thrombosis after Sirolimus-Eluting Stent Implantation
Influences of antiplatelet therapy discontinuation on clinical outcomes after drug-eluting stent implantation are not adequately addressed yet. In an observational study in Japan, two-year outcomes were assessed in 12,824 patients undergoing sirolimus-eluting stent (SES) implantation at 37 centers. Data on compliance and adherence to antiplatelet therapy were prospectively collected. Complete one-year (median of 494 days; interquartile range: 388 – 730 days) follow-up was achieved in 96% of patients. Incidences of definite stent thrombosis (ST) were 0.35% at 30 days, 0.59% at 1 year and 0.78% at 2 years. Thienopyridine use was maintained in 97%, 63% and 52% of pts at 30 days, 1 year and 2 years, respectively. The majority of patients (89%) of early ST were on dual antiplatelet therapy at the time of ST. The prevalence of dual therapy was 52% for late ST and 36% for very late ST, respectively. Patients who discontinued both thienopyridine and aspirin, but not those who discontinued thienopyridine only, had significantly higher rate of ST as compared with those who continued both in the intervals of 31–180 days and 366 –548 days post stent implantation (Table⇓). Among 24 patients who had ST after any antiplatelet therapy discontinuation, the majority of ST events except one occurred beyond 1 week after discontinuation. Adjusted death or myocardial infarction rates at 24 months were 4.2% for patients on thienopyridine and 4.5% for patients off thienopyridine (p=0.55) in the 6-month landmark analysis. Discontinuation of both thienopyridine and aspirin, but not of thienopyridine therapy alone, is associated with an increased ST risk. Since the majority of ST events occurred beyond 1 week after discontinuation, it seems practically important to make the duration of discontinuation as short as possible. Landmark analysis did not suggest apparent clinical benefit of thieopyridine use beyond 6 months after SES implantation.