Analysis of risk factors for adverse events in elderly patients with heart failure undergoing coronary artery bypass grafting and development of a nomogram model: A retrospective cohort study

To identify risk factors associated with adverse postoperative outcomes in elderly patients with heart failure undergoing coronary artery bypass grafting (CABG) and to develop a predictive nomogram. A retrospective analysis was conducted on 1,075 elderly patients (≥70 years) with left ventricular ejection fraction (LVEF) <40% who underwent CABG at Tianjin Chest Hospital between January 2010 and June 2025. Using R software, patients were randomly assigned to training (n=752) and validation (n=323) sets in a 7:3 ratio. Based on the occurrence of postoperative serious adverse events (PSAEs), which included reintubation/tracheostomy, perioperative myocardial infarction, stroke, cardiac arrest/ventricular fibrillation, cardiac tamponade, pulmonary embolism, pneumonia, renal failure, multiple organ dysfunction, and all-cause mortality, the training set was categorized into PSAEs (n=152) and no-PSAEs (n=600) groups. Univariate and multivariate logistic regression analyses were employed to identify risk factors for post-surgical adverse events (PSAEs), and a nomogram was constructed and internally validated. The model's performance was evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis (DCA). Univariate analysis revealed significant differences in serum creatinine, hypersensitive C-reactive protein (hs-CRP), brain natriuretic peptide (BNP), albumin, preoperative intra-aortic balloon pump (IABP) placement, mode of preoperative ventilatory support, concomitant atrial fibrillation (AF) maze procedure, left ventricular end-diastolic dimension (LVEDD), and hyperlactatemia (all P<0.05). Multivariate analysis identified preoperative IABP placement (OR=2.740, 95% CI=1.216–6.175, P=0.015), non-invasive positive pressure ventilation (NIPPV) (OR=3.435, 95% CI=1.401–8.422, P=0.007), high-flow nasal oxygen (HFNO) therapy (OR=3.039, 95% CI=1.022–9.035, P=0.046), hyperlactatemia (OR=2.829, 95% CI=1.584–5.051, P<0.001), LVEDD (OR=3.621, 95% CI=1.171–11.212, P=0.026), and concomitant AF maze procedure (OR=1.431, 95% CI=0.528–3.880, P=0.037) as independent risk factors for PSAEs. A nomogram that incorporates these five predictors demonstrated good discriminative ability, with an area under the ROC curve of 0.819 (95% CI: 0.659–0.879). Internal validation using bootstrap resampling (1,000 repetitions) and the Hosmer-Lemeshow test (χ²=1.141, P=0.888) indicated a good model fit. Decision curve analysis showed a net benefit within a threshold probability range of 12%–90%. Preoperative IABP placement, NIPPV or HFNO ventilatory support, LVEDD, concomitant AF maze procedure, and hyperlactatemia are independent risk factors for adverse outcomes in elderly patients undergoing CABG. The constructed nomogram provides a practical tool for predicting postoperative PSAEs in this high-risk population.