ABSTRACT: Background Perioperative atrial fibrillation (POAF) is common in patients undergoing cardiac surgery. Conflicting evidence exists whether patients with POAF after cardiac surgery have an increased long-term risk of stroke and other adverse events. Methods and Results We prospectively followed for up to 5 years 4624 patients without prior atrial fibrillation who underwent coronary artery bypass grafting in an international study. POAF was defined as atrial fibrillation that occurred during the initial hospitalization for surgery, lasted for ≥5 minutes, and required treatment. Outcomes assessed were a composite of death, nonfatal myocardial infarction or nonfatal stroke, and its individual components. Median age was 67 years, and 778 (16.8%) had an episode of POAF. The incidence of the composite outcome was 6.84 and 4.10 per 100 patient-years in patients with and without POAF, and the incidence of stroke was 0.75 versus 0.45, respectively. The adjusted hazard ratios (aHRs) were 1.36 (95% CI, 1.16-1.59) for the composite outcome; 1.33 (95% CI, 1.10-1.61) for death; 1.58 (95% CI, 1.23-2.02) for myocardial infarction, and 1.27 (95% CI, 0.81-2.00) for stroke. In a landmark analysis excluding events of the initial hospital admission, the aHRs were 1.26 (95% CI, 1.03-1.54) for the composite outcome, 1.28 (95% CI, 1.03-1.59) for death, 1.70 (95% CI, 0.86-3.36) for myocardial infarction, and 1.07 (95% CI, 0.59-1.93) for stroke. At hospital discharge, 10.7% and 1.4% of patients with and without POAF received oral anticoagulation, respectively. Conclusions Patients with POAF after cardiac surgery had an increased long-term risk of adverse outcomes, mainly death and myocardial infarction. The risk of stroke was low and not increased in patients with POAF. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00463294.
