Incidence and predictors of atrial fibrillation after coronary artery bypass surgery: detection by event loop recorder monitoring from a contemporary multicentre cohort

Background Atrial fibrillation (AF) is a frequent complication after cardiac surgery. We explored the incidence and predictors of post-operative AF at 30-day follow-up in an unselected multi-centre cohort of patients undergoing elective coronary artery bypass grafting (CABG) in contemporary practice. Methods and results We enrolled 740 consecutive patients scheduled for elective CABG with or without valve surgery. Cardiac rhythm was continuously monitored for 15 days after surgery by an ambulatory event loop recorder. Clinical follow-up for the occurrence of arrhythmias was performed for the next 15 days by office visits. The primary end point was the incidence of AF at 30-day follow-up. Mean age was 56.5 +/- 8.9 years; 69.5% were males; 80% had diabetes. All patients completed 30-day follow-up. At the end of 30 days, AF occurred in 77 patients (10.4%). Most episodes (47 out of 77 episodes, 61%) of AF occurred during post-operative day 2. Episodes of AF were very rare after the first 5 post-operative days (3 out of 77 episodes, 3.9%). Multivariable regression analysis identified the following independent predictors of AF at 30-day follow-up: the lack of beta blocker use (hazard ratio 0.37, 95% confidence interval 0.21-0.64, P < 0.001), and the preoperative left atrial volume index (hazard Ratio 2.21, 95% confidence interval 1.79-2.74, P < 0.001). Conclusions In patients undergoing elective CABG, the incidence of post-operative AF at 30-day follow-up is rather low; the lack of beta blocker use in the perioperative period, and the preoperative left atrial volume index independently predicted the occurrence of AF at 30 days.