Objective To investigate the risks and benefits of prolonged dual antiplatelet therapy (DAPT: thienopyridine plus aspirin) following placement of drug-eluting stents (DES). The optimal duration of DAPT is not well established.
Methods We analyzed a prospective registry of 2,050 patients with sirolimus-eluting stents during a 5-year follow-up. We divided 1,691 patients into two groups according to DAPT duration (DAPT ≤12 months (n=749) and DAPT >12 months (n=942)) and compared the clinical outcomes using a landmark analysis.
Results The frequencies of major adverse cardiac events (MACE: 15.6% vs. 18.2%), death (10.0% vs. 11.5%), myocardial infarction (2.3% vs. 2.1%), target lesion revascularization (4.5% vs. 6.3%) and stent thrombosis (0.8% vs. 0.8%) were similar between the two groups. However, the frequency of bleeding was higher in the DAPT >12 months group (1.1% vs. 2.6%, p=0.030). The adjusted 12-month landmark analysis showed no differences in the incidence of MACE (hazard ratio (HR) 0.892; 95% confidence interval (CI) 0.689-1.155; p=0.385) or a composite of target vessel revascularization, cardiac death and myocardial infarction (target vessel failure: HR 0.922; 95% CI 0.678-1.255; p=0.606). There were no differences in the frequency of stent thrombosis between the two groups during years 2 to 5 after stenting; however, with regard to bleeding, an increase in the frequency of hemorrhage events was observed after four years from the index procedures in the DAPT >12 months group.
Conclusion DAPT performed beyond 12 months is associated with increased an frequency of bleeding complications and does not prevent the incidence of MACE, including stent thrombosis, during five years of follow-up after sirolimus-eluting stent implantation. Conducting larger, randomized studies will therefore be needed to confirm this finding.