Background: Preoperative atrial fibrillation has been identified as a risk factor for reduced long-term survival after coronary artery bypass grafting. This study sought to determine whether atrial fibrillation is merely a marker for high-risk patients or an independent risk factor for time-related mortality.
Methods: From 1972 to 2000, 46,984 patients underwent primary isolated coronary artery bypass grafting; 451 (0.96% prevalence) had electrocardiogram-documented preoperative atrial fibrillation (n = 411) or flutter (n = 40). Characteristics of patients with and without atrial fibrillation were contrasted by multivariable logistic regression to form a propensity score. With this, comparable groups with and without atrial fibrillation were formed by pairwise propensity-matching to assess survival.
Results: Patients with preoperative atrial fibrillation were older (67 +/- 9.0 versus 59 +/- 9.8 years, p < 0.0001), had more left ventricular dysfunction (66% versus 52%, p < 0.0001) and hypertension (73% versus 59%, p < 0.0001), but less severe angina (39% moderate or severe versus 49%, p < 0.0001). Many of these factors are themselves predictors of increased time-related mortality. In propensity-matched patients, survival at 30 days and at 5 and 10 years for patients with versus without atrial fibrillation was 97% versus 99%, 68% versus 85%, and 42% versus 66%, respectively, a survival difference at 10 years of 24%. Median survival in patients with atrial fibrillation was 8.7 years versus 14 years for those without it.
Conclusions: Atrial fibrillation in patients undergoing coronary artery bypass grafting is a marker for high-risk patients; in addition, atrial fibrillation itself substantially reduces long-term survival. Thus, if patients in atrial fibrillation require surgical revascularization, it is appropriate to consider performing a concomitant surgical ablation procedure.