Fluid Balance and Risk of Postoperative Atrial Fibrillation after On-pump Coronary Artery Bypass Grafting Surgery

Background: Postoperative atrial fibrillation (POAF) is a common complication after coronary artery bypass grafting (CABG) and is associated with increased adverse outcomes. However, the relationship of fluid balance and POAF is not clear yet. Accordingly, this study aims to study the relationship of fluid balance and POAF, and to evaluate the other risk factors of POAF in patients undergoing elective on-pump CABG with or without valve surgery in our center. Methods: A retrospective study between October 2018 and December 2022 including 261 patients who underwent CABG undergoing cardiopulmonary bypass was performed. The fluid balance on the first 4 days in the intensive care unit (ICU) and other potential perioperative risk factors for POAF were collected and analyzed using univariate and multivariate analyses to identify risk factors following CABG. The in-hospital adverse outcomes of POAF were also evaluated. Results: 261 adult CABG patients were evaluated, of whom 22 were excluded due to a history of atrial fibrillation or other causes. Among them, 72 patients developed POAF (30.1%). The mean fluid balance was negative on the first 3 days. Negative fluid balance was less on postoperative day 0 (POD 0) in those developing POAF than in those not developing POAF (–12.88 ± 12.47 vs. –17.48 ± 10.03 mL/kg, p = 0.003). No differences were noted for POD 1 and POD 2. Multiple logistic regression analysis showed age >60 years (adjusted odds ratio (OR), 3.86 [95% confidence interval (CI): 1.99 to 7.48]), left atrial antero-posterior (AP) dimension >42 mm (adjusted OR, 2.68 [95% CI: 1.45 to 4.93]), total blood transfusions >400 mL (adjusted OR, 1.96 [95% CI: 1.05 to 3.63]), and positive fluid balance on POD 0 (adjusted OR, 2.93 [95% CI: 1.01 to 8.51]) were independent perioperative risk factors for POAF. Conclusions: The incidence of POAF is not significantly reduced even with a fluid restriction strategy after CABG, and positive fluid balance on the day of surgery is a risk factor for POAF, rather than on POD 1 and POD 2. In addition, advanced age, left atrial enlargement, and increased perioperative blood transfusion are all risk factors for POAF.