Background: Postoperative atrial fibrillation (POAF) is a common complication after coronary artery bypass grafting (CABG), linked to oxidative stress from cardiopulmonary bypass. This study evaluated the association between preoperative high-dose vitamin C supplementation and POAF incidence. Methods: A prospective observational study was conducted in 2005 on 312 patients undergoing elective CABG. Based on surgeon preference, 148 patients received oral vitamin C (2g daily) for ≥5 days preoperatively (Vitamin C Group), and 164 received none (Control Group). All received standardized anesthesia and surgery. The primary outcome was the incidence of POAF within the first 5 postoperative days, confirmed by telemetry/ECG. Secondary outcomes included duration of POAF, hospital length of stay (LOS), and complications. Statistical analyses used Chi-square, t-tests, and logistic regression. Results: The incidence of POAF was significantly lower in the Vitamin C group (22.3% vs. 34.8%, p=0.012). Postoperative LOS was also shorter in the Vitamin C group (7.8 ± 2.1 days vs. 8.7 ± 3.0 days, p=0.003). The median duration of AF and complication rates were not significantly different. After adjustment for confounders, vitamin C supplementation remained an independent predictor of reduced POAF risk (OR 0.55, 95% CI 0.33-0.91). Conclusion: Preoperative high-dose vitamin C supplementation was associated with a significant reduction in POAF incidence and hospital stay after CABG. This supports further investigation of antioxidant strategies in perioperative care.

Postoperative Atrial Fibrillation; Coronary Artery Bypass Grafting; Vitamin C; Antioxidants; Oxidative Stress.