TOPLINE

Patients with overweight had lower 365-day mortality following coronary artery bypass grafting (CABG) than those with normal weight. The relationship between BMI and mortality followed a U-shaped pattern.

METHODOLOGY

• A retrospective cohort study analyzed data from 5790 adult patients (78.93% men) who underwent CABG at a Boston-based center between 2008 and 2019 to examine how BMI related to mortality after CABG.
• Patients were categorized into six BMI groups: underweight (BMI < 18.5), normal (18.5 to < 25), overweight (25 to < 30), class I obesity (30 to < 35), class II obesity (35 to < 40), and class III obesity (≥ 40).
• The outcomes were all-cause mortality within 7, 14, 28, and 365 days after CABG.
• Machine learning algorithms identified key mortality predictors, with models evaluated using area under the curve (AUC) and decision curve analysis.

TAKEAWAY

• Patients with overweight had significantly lower 365-day mortality than those with normal weight (adjusted odds ratio [aOR], 0.659; P = .018). BMI showed a U-shaped relationship with mortality.
• The protective effect of overweight persisted in patients aged ≥ 65 years (P < .05) but was not statistically significant in younger patients or female subgroups after covariate adjustment.
• Key mortality drivers varied by BMI category: acute physiology scores and coagulation markers in patients with underweight; inflammatory markers and comorbidity burden in those with normal weight; hemodynamic stability and metabolic parameters in those with overweight; and glucose control and liver function in those with severe obesity.
• The extreme gradient boosting (XGBoost) model achieved the highest predictive performance for 365-day mortality (AUC, 0.70), with the Charlson Comorbidity Index emerging as the most important predictor for long-term mortality.

IN PRACTICE

"The findings of this study indicate that the influence of BMI should be comprehensively evaluated in risk assessment following CABG," the authors of the study wrote.

SOURCE

The study was led by Tianpei Mou, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University in Wenzhou, China. It was published online on July 27 in Open Heart.

LIMITATIONS

The retrospective design prevented establishing any cause-effect relationship and may have been prone to information bias. BMI could not distinguish fat mass from muscle mass. Fewer patients in the underweight group may have introduced statistical bias.

DISCLOSURES

No specific funding was reported for the study. The authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.