Compared with matched controls, patients with postoperative atrial fibrillation (POAF) have increased long-term AF after CABG, and POAF is further associated with increased ischemic stroke, heart failure and mortality even after adjustment for AF.

Objective: To analyze (1) associations between postoperative atrial fibrillation (POAF) after CABG and long-term cardiovascular outcome, (2) whether associations were influenced by AF during follow-up, and (3) if morbidities associated with POAF contribute to mortality.
Methods: An observational cohort study of 7145 in-hospital survivors after isolated CABG (1996-2012), with preoperative sinus rhythm and without AF history. Incidence of AF was compared with matched controls. Time-updated covariates were used to adjust for POAF-related morbidities during follow-up, including AF.
Results: Thirty-one percent of patients developed POAF. Median follow-up was 9.8 years. POAF patients had increased AF compared with matched controls (HR 3.03; 95% CI 2.66-3.49), while AF occurrence in non-POAF patients was similar to controls (1.00; 0.89-1.13). The observed AF increase among POAF patients compared with controls persisted over time (> 10 years 2.73; 2.13-3.51). Conversely, the non-POAF cohort showed no AF increase beyond the first postoperative year. Further, POAF was associated with long-term AF (adjusted HR 3.20; 95% CI 2.73-3.76), ischemic stroke (1.23; 1.06-1.42), heart failure (1.44; 1.27-1.63), overall mortality (1.21; 1.11-1.32), cardiac mortality (1.35; 1.18-1.54), and cerebrovascular mortality (1.54; 1.17-2.02). These associations remained after adjustment for AF during follow-up. Adjustment for other POAF-associated morbidities weakened the association between POAF and overall mortality, which became non-significant.
Conclusions: Patients with POAF after CABG had three times the incidence of long-term AF compared with both non-POAF patients and matched controls. POAF was associated with long-term ischemic stroke, heart failure, and corresponding mortality even after adjustment for AF during follow-up. The increased overall mortality was partly explained by morbidities associated with POAF.