Factors Associated with Hospital Length of Stay After Coronary Artery Bypass Grafting: Perioperative Characteristics and Postoperative Complication Burden

Background: We evaluated factors associated with postoperative hospital length of stay (LOS) after elective isolated coronary artery bypass grafting (CABG), including contemporaneous associations with postoperative complications. Methods: This single-center retrospective cohort included 1493 patients undergoing elective isolated CABG from January 2020 to September 2025. Among 1449 30-day survivors, cumulative postoperative hospital days were modeled using negative binomial regression; LOS > 7 days was the data-derived, center-specific binary outcome. Secondary models assessed postoperative events. Exploratory mortality analysis used Firth logistic regression with bootstrap validation. Results: Median postoperative LOS was 7 days; 406 survivors (28.0%) had LOS > 7 days. Longer LOS was associated with higher body mass index (IRR per 5 kg/m2, 1.05), diabetes (IRR, 1.07), hypertension (IRR, 1.09), chronic obstructive pulmonary disease (IRR, 1.21), lower left ventricular ejection fraction (IRR per 5-percentage-point decrease, 1.04), lower hemoglobin (IRR per 1 g/dL decrease, 1.04), and longer cardiopulmonary bypass (CPB) duration (IRR per 30 min, 1.11). Infection (IRR, 1.46), postoperative atrial fibrillation (IRR, 1.19), and prolonged mechanical ventilation (IRR, 1.54) were contemporaneous correlates. In exploratory mortality analysis, EuroSCORE II (odds ratio per doubling, 2.01) and CPB duration (odds ratio per 30 min, 1.78) were associated with mortality; the optimism-corrected area under the curve was 0.799. EuroSCORE II alone showed moderate discrimination. Conclusions: LOS reflected baseline reserve, operative burden, and postoperative complications. Without event timing, associations with postoperative events are hospitalization-level and neither prospective nor causal.