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.