[Impact of prolonging dual antiplatelet therapy on long-term prognosis of elderly patients with coronary heart disease complicated with diabetes mellitus undergoing drug-eluting stent implantation]

Objective: To explore and compare the effect of standard or prolonged dual antiplatelet therapy (DAPT) on the long-term prognosis of elderly patients with coronary heart disease complicated with diabetes mellitus after drug-eluting stent (DES) implantation. Methods: Consecutive patients with diabetes mellitus, ≥65 years old, underwent DES implantation, and had no adverse events within 1 year after operation underwent percutaneous coronary intervention (PCI) from January to December 2013 in Fuwai Hospital were enrolled in this prospective cohort study. These patients were divided into three groups according to DAPT duration: standard DAPT duration group (11 ≤ DAPT duration≤ 13 months) and prolonged DAPT duration group (13<DAPT duration≤ 24 months; DAPT duration>24 months). All the patients were followed up at 1, 6 months, 1, 2 and 5 years in order to collect the incidence of major adverse cardiovascular and cerebrovascular events (MACCE), and type 2 to 5 bleeding events defined by the Federation of Bleeding Academic Research (BARC). MACCE were consisted of all cause death, myocardial infarction, target vessel revascularization or stroke. The incidence of clinical adverse events were compared among 3 different DAPT duration groups, and Cox regression model were used to analyze the effect of different DAPT duration on 5-year long-term prognosis. Results: A total of 1 562 patients were enrolled, aged (70.8±4.5) years, with 398 female (25.5%). There were 467 cases in standard DAPT duration group, 684 cases in 13<DAPT duration≤ 24 months group and 411 cases in DAPT duration>24 months group. The patients in standard DAPT duration group and the prolonged DAPT duration groups accounted for 29.9% (467/1 562) and 70.1% (1 095/1 562), respectively. The 5-year follow-up results showed that the incidence of all-cause death in 13<DAPT duration≤ 24 months group (4.8%(33/684) vs. 8.6%(40/467),P=0.011) and DAPT duration>24 month group(4.1%(17/411) vs. 8.6%(40/467),P=0.008) were significantly lower than in standard DAPT group. The incidence of myocardial infarction in 13<DAPT duration≤ 24 months group was lower than in standard DAPT duration group (1.9%(13/684) vs. 5.1%(24/467),P=0.002). The incidence of MACCE in 13<DAPT duration≤ 24 months group was the lowest (standard DAPT duration group, 13<DAPT duration≤ 24 months group and DAPT duration>24 month group were 19.3% (90/467), 12.3% (84/684), 20.2% (83/411), respectively, P<0.001). There was no significant difference in the incidence of stroke and bleeding events among the three groups (all P>0.05). Multivariate Cox analysis showed that compared with the standard DAPT group, prolonged DAPT to 13-24 months was negatively correlated with MACCE (HR=0.601, 95%CI 0.446-0.811, P=0.001), all-cause death (HR=0.568, 95%CI 0.357-0.903, P=0.017) and myocardial infarction (HR=0.353, 95%CI 0.179-0.695, P=0.003). DAPT>24 months was negatively correlated with all-cause death (HR=0.687, 95%CI 0.516-0.913, P=0.010) and positively correlated with revascularization (HR=1.404, 95%CI 1.116-1.765, P=0.004). There was no correlation between prolonged DAPT and bleeding events. Conclusions: For elderly patients with coronary heart disease complicated with diabetes mellitus underwent DES implantation, and had no MACCE and bleeding events within 1 year after operation, appropriately prolonging of the DAPT duration is related to the reduction of the risk of cardiovascular adverse events. Patients may benefit the most from the DAPT between 13 to 24 months. In addition, prolonging DAPT duration does not increase the incidence of bleeding events in this patient cohort.