Increased late mortality after coronary artery bypass surgery complicated by isolated new-onset atrial fibrillation: a comprehensive propensity-matched analysis

Abstract

Objectives: The association of new-onset postoperative atrial fibrillation (POAF) and late death after coronary artery bypass grafting (CABG) has been confounded by the frequent concomitant serious complications that co-occur with POAF. We aimed to define the magnitude and time dependence of the effect of isolated POAF on late survival after uncomplicated CABG to comprehensively account for comorbidity and perioperative confounding factors.

Methods: Nonsalvage CABG patients with no history of AF, no concomitant aortic or valvular surgery, and no perioperative complications other than POAF were studied (n=6305). Patients were divided into AF (n=1211, 68 years old, 72% male) and no-AF (n=5094, 63 years old, 70% male) groups. Propensity matching was done using 55 patient variables, including coronary grafts, completeness of revascularization, and transfusion data. The AF effect was quantified using time-segmented hazard ratios by Cox regression analysis.

Results: Single (1-to-1), double (1-to-2), and triple (1-to-3) propensity matching of the AF and no-AF was achieved for 1196, 993, and 719 cases, respectively. The AF group showed significantly worse, yet time-varying, 0- to 18-year survival: 0 to 1 year, HR, 1.18 (95% confidence interval, 0.77-1.81); 1 to 6 years, HR, 1.37 (95% confidence interval, 1.12 to 1.67); and 6 to 17 years, HR, 1.25 (95% confidence interval, 1.05 to 1.49).

Conclusions: Isolated POAF was associated with a time-varying increase in mortality after CABG. Given these findings and the high incidence of POAF, efforts to reduce POAF should be pursued to potentially improve resource usage, morbidity, and mortality.