Comparative effectiveness of clopidogrel versus aspirin as a maintenance monotherapy 1 year after coronary artery bypass grafting.

Abstract

Data on the safety and efficacy of clopidogrel (CPD) monotherapy after coronary artery bypass grafting (CABG) are limited. We compared the clinical outcomes and graft patency rates during 4 years in CABG patients who maintained CPD or aspirin after 1 year of dual antiplatelet therapy (DAPT) use. A total of 671 patients who maintained 1-year DAPT after CABG with all grafts patent on one-year follow-up angiography and switched to single antiplatelet therapy (SAPT) using CPD (n = 272) or aspirin (n = 399) between January 2009 and December 2015 were enrolled. Propensity score matching analysis was used, and 227 pairs were matched in a 1:1 ratio. Overall mortality, cardiac mortality, and major adverse events, including all-cause mortality, acute myocardial infarction, coronary reintervention or reoperation, ischaemic stroke, and major bleeding, were compared. Graft patency was evaluated using graft angiography 5 years post-surgery. Overall survival and the incidence of major adverse events during the 4-year follow-up did not differ significantly between the groups when un-matched (hazard ratio [HR], 95% confidence interval [CI]=1.24, 0.71 to 2.15, P = 0.46 and HR, 95% CI = 1.22, 0.77 to 1.92, P = 0.41, respectively) or matched (HR, 95% CI = 1.05, 0.55 to 2.01, P = 0.89 and HR, 95% CI = 1.01, 0.60 to 1.73, P = 0.96, respectively). In the postoperative 5-year graft angiography, new graft occlusion was found in 3.2% and 4.7% of patients and newly occurred graft occlusion rates of distal anastomoses were 1.2% and 1.6% in the CPD and aspirin groups, respectively, and were not statistically different between the 2 groups (P = 0.39 and 0.63, respectively). Changes of antiplatelet regimen were needed in 22.8% (91 of 399) of aspirin group and in 2.2% (6 of 272) of CPD group from the initiation of SAPT (P < 0.001). In this series of patients undergoing CABG who received DAPT and remained stable for 1 year, SAPT maintenance with CPD or aspirin did not show any significant differences in 4-year outcomes such as all-cause mortality, major adverse events, and newly occurring graft occlusion. However, more patients taking aspirin required changes in antiplatelet regimens to other antiplatelet or anticoagulation therapies.