Background: This retrospective multicenter study investigates the impact of obesity on short-term surgical outcomes in patients with heart failure and reduced ejection fraction (HFrEF) undergoing coronary artery bypass grafting (CABG). Given the rising global prevalence of obesity and its known cardiovascular implications, understanding its specific effects in high-risk groups like HFrEF patients is crucial. Methods: The study analyzed data from 574 patients undergoing CABG across four German university hospitals from 2017 to 2023. Patients were stratified into ‘normal weight’ (n = 163) and ‘obese’ (n = 158) categories based on BMI (WHO classification). Data on demographics, clinical measurements, health status, cardiac history, intraoperative management, postoperative outcomes, and laboratory insights were collected and analyzed using Chi-square, ANOVA, Kruskal–Wallis, and binary logistic regression. Results: Key findings are a significant higher mortality rate (6.96% vs. 3.68%, p = 0.049) and younger age in obese patients (mean age 65.84 vs. 69.15 years, p = 0.003). Gender distribution showed no significant difference. Clinical assessment scores like EuroScore II and STS Score indicated no differences. Paradoxically, the preoperative left ventricular ejection fraction (LVEF) was higher in the obese group (32.04% vs. 30.34%, p = 0.026). The prevalence of hypertension, COPD, hyperlipidemia, and other comorbidities did not significantly differ. Intraoperatively, obese patients required more packed red blood cells (p = 0.026), indicating a greater need for transfusion. Postoperatively, the obese group experienced longer hospital stays (median 14 vs. 13 days, p = 0.041) and higher ventilation times (median 16 vs. 13 h, p = 0.049). The incidence of acute kidney injury (AKI) (17.72% vs. 9.20%, p = 0.048) and delirium (p = 0.016) was significantly higher, while, for diabetes prevalence, there was an indicating a trend towards significance (p = 0.051) in the obesity group, while other complications like sepsis, and the need for ECLS were similar across groups. Conclusions: The study reveals that obesity significantly worsens short-term outcomes in HFrEF patients undergoing CABG, increasing risks like mortality, kidney insufficiency, and postoperative delirium. These findings highlight the urgent need for personalized care, from surgical planning to postoperative strategies, to improve outcomes for this high-risk group, urging further tailored research.
