Effect of postoperative atrial fibrillation on early and mid-term outcomes of coronary artery bypass graft surgery

OBJECTIVES: The long-term prognostic role of postoperative atrial fibrillation (POAF) in cardiovascular outcomes in patients undergoing cardiac surgery is uncertain. Our goal was to investigate the impact of new-onset POAF on midterm adverse cardiovascular events after coronary artery bypass graft (CABG) surgery. METHODS: We performed a retrospective cohort study of patients who underwent isolated CABG without a preoperative history of atrial fibrillation/flutter. POAF was defined as episodes of AF lasting >= 30s during the hospitalization period. The effect of POAF on midterm all-cause mortality and cerebrovascular accidents/transient ischaemic attacks (CVA/TIA) was assessed using a Cox proportional hazard regression model in a competing risk setting. Additional analyses were performed on patients surviving an event-free early postoperative period (i.e. within 30 postoperative days after the index operation). RESULTS: A total of 9,310 patients were followed for a median duration of 48.7 months. New-onset POAF was associated with an increased risk of midterm all-cause mortality (HR = 1.648, 95% confidence interval: 1.402-1.937; P < 0.001) and CVA/TIA (subdistribution-HR = 1.635, 1.233-2.167; P = 0.001). After excluding patients who died during the early postoperative period, POAF remained significantly associated with higher late all-cause mortality (HR = 1.518, 1.273-1.811; P < 0.001). However, the risk of late CVA/TIA in patients who survived the early postoperative period without having a stroke was similar between those with and without POAF (subdistribution-HR = 1.174, 0.797-1.729; P = 0.418). CONCLUSIONS: New-onset POAF after CABG is associated with an increased risk of midterm overall mortality and stroke. However, late stroke risk is likely similar between patients with and without POAF who survive an event-free early postoperative period.