Influence of race on atrial fibrillation after cardiac surgery

Despite having fewer risk factors for atrial fibrillation (AF), white patients have a greater prevalence of AF in the community than black patients, and a genetic basis has been postulated. However, it is unknown whether occurrence of new-onset AF after cardiac surgery is different in white versus black patients, and secondarily, other non-Caucasian patients.

From 1995 through 2005, 20 282 white, 1323 black, and 1919 other non-Caucasian patients in sinus rhythm underwent coronary artery bypass grafting with or without valve surgery. To adjust for clinical and socioeconomic confounders, we performed propensity-adjusted analyses; 7093 white patients (35%) had postoperative AF, compared with 255 (22%) black patients and 550 (29%) other non-Caucasians (P<0.0001). Whites were older than black patients, had higher socioeconomic position, and greater left atrial size but were less likely to have hypertension or congestive heart failure. In 847 propensity-matched patient pairs, postoperative AF occurred more frequently in white than in black patients (odds ratio, 1.74; 95% confidence interval, 1.7-1.78). Other than higher occurrence of bradycardia requiring pacing and reintubation in white patients, occurrence of other postoperative complications, hospital mortality, and length of postoperative stay were similar. Age and valvular surgery were the strongest predictors of AF irrespective of race.

White patients had a markedly higher risk of postoperative AF than black and other non-Caucasian patients. The cause for racial differences of arrhythmic risk is unknown, but a genetic predisposition is plausible. Our results have implications for risk stratification and mechanistic understanding of postoperative AF.