Atrial fibrillation (AF) in the post–cardiac surgery setting has several known risk factors, but the recent report by Lahiri et al proposes that African Americans benefit from a reduced incidence of this common postoperative arrhythmia. We would like to contest the investigators’ statement that “to date, there have been no published studies searching for differences in the risk for postoperative AF between African Americans and European Americans.” In general, AF has been found to have a lower prevalence among blacks, and although the investigators contend that their finding is an initial report in the postoperative setting, it should be highlighted that previous studies in post–cardiac surgery patients have found consistently similar results.
For instance, in a nested case-control study of patients who underwent coronary artery bypass grafting, it was shown that African Americans, despite having significantly longer hospitalizations postoperatively, were less likely to experience postoperative AF than Caucasians (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.49 to 0.84). Similarly, in a large cohort of post–cardiac surgery patients, Zacharias et al found white race to be an independent predictor of postoperative AF (adjusted OR 1.33, 95% CI 1.07 to 1.66). More recently, Nazeri et al in propensity-matched patients after isolated coronary artery bypass graft surgery found that Caucasian race was an independent predictor of postoperative AF (OR 1.7, 95% CI 1.3 to 2.2). Last, in a recent examination of 10,390 post–cardiac surgery patients, Caucasian race was found to be significantly and independently associated with postoperative AF (adjusted OR 1.51).
Therefore, on the basis of ≥5 available studies addressing race and ethnicity and risk for postoperative AF, black race appears to confer approximately an adjusted 30% to 40% lower risk for developing postoperative AF compared to Caucasian race. The 4 aforementioned studies add support to the findings of Lahiri et al and substantiate that blacks regularly demonstrate a lower prevalence of AF, including studies specifically addressing post–cardiac surgery patients.