Racial Disparities in Atrial Fibrillation After Coronary Artery Bypass: Impact of Left Atrial Volume.

Background: Prior studies have demonstrated a lower prevalence of postoperative atrial fibrillation (POAF) in Black, Hispanic, Asian, and Native American patients compared with White cohorts after coronary artery bypass grafting. We hypothesized that preoperative differences in left atrial size may explain this disparity.

Methods: We assessed the incidence of new POAF in 1218 patients (215 minority patients and 1003 White patients) undergoing isolated, first-time coronary artery bypass grafting from January 2017 through September 2022. Preoperative left atrial volume index (LAVi) was assessed by transthoracic echocardiography.

Results: Minority patients were younger and more likely to be female, with more comorbidities, including diabetes, prior stroke, and dialysis. There was no difference in postoperative mortality, stroke, renal failure, or reoperation for bleeding between minority and White patients. Whereas minority patients had higher blood product use and longer intensive care unit and postoperative lengths of stay, they experienced a lower incidence of new POAF (19.5% [42/215] vs 29.5% [292/1003]; = 0.02). Mean LAVi was similar between minority and White patients (30.3 ± 12.6 mL/m vs 29.9 ± 10.1 mL/m;  = .64). However, for White patients, LAVi was higher for patients with POAF than for patients without POAF (31.3 ± 10.9 mL/m vs 29.3 ± 9.7 mL/m;  = .007), whereas for minority patients, LAVi was similar for patients with and without POAF (30.7 ± 26.0 mL/m vs 30.3 ± 11.7 mL/m;  = .84).

Conclusions: Despite more comorbidities, higher transfusion rates, and longer length of stay, minority patients had a significantly lower incidence of POAF compared with White patients but no difference in preoperative LAVi. Larger LAVi may be predictive of POAF in White patients but not in minority patients.