Postoperative atrial fibrillation is associated with late mortality after coronary surgery, but not after valvular surgery.

BACKGROUND: Numerous studies have attempted to determine the etiology and prophylactic measures concerning atrial fibrillation (AF) after cardiac surgery. However, limited data are available analyzing the association between postoperative AF and late mortality. We sought to determine if AF after cardiac surgery affects postoperative survival.
METHODS: All cardiac surgery patients (n = 9,495) undergoing cardiac surgery between January 1994 and December 2004 were studied. The study population comprised coronary artery bypass graft surgery (CABG [n = 7,621]), valvular surgeries (n = 995), and their combination (n = 879). Patients affected by postoperative AF were identified, and long-term survival was obtained from Swedish population registry and evaluated using Cox proportional hazards methods to adjust for baseline differences.
RESULTS: The overall AF incidence was 26.7%, subdivided into 22.9%, 39.8%, and 45.2% for CABG, valve surgery, and combined procedures, respectively. The median follow-up for the entire study population was 7.9 years (maximum, 13.4). Postoperative AF independently affected long-term survival in CABG patients (hazard ratio 1.22; 95% confidence interval: 1.08 to 1.37). For isolated valvular surgery or combined procedures, AF was not significantly associated with long-term survival (hazard ratio 1.21, 95% confidence interval: 0.92 to 1.58; and hazard ratio 1.15, 95% confidence interval: 0.90 to 1.46, respectively).
CONCLUSIONS: Postoperative AF increases late mortality after isolated CABG surgery only. This finding was not statistically confirmed after isolated or combined valvular procedures. Our results draw the attention to possible AF recurrence after hospital discharge, indicating a strict postoperative surveillance.