Challenging BMI: Fat Mass Indices for Improved Postoperative Risk Prediction in CABG Patients

This study investigated the effect of preoperative fat mass index (FMI), fat-free mass index (FFMI), fat mass ratio (FMR), and fat-free mass ratio (FFMR) on postoperative morbidity and mortality in coronary artery bypass grafting (CABG) patients. About 120 patients were included in this prospective study. The patients' FMI, FFMI, FMR, and FFMR were evaluated preoperatively along with other clinically significant data. The postoperative morbidities were recorded. Receiver operating characteristic (ROC) curve analyses were made to determine threshold values of FMR, FFMR, and FMI for wound dehiscence. The multivariate logistic regression analysis was made to assess the independent risk factors for infection site leakage. ROC analysis yielded threshold values of FMR 0.26, FFMR 0.73, and FMI 7.46. FMI, FMR, and FFMR were associated with parameters including body mass index (BMI), diabetes, and wound dehiscence (80.7% sensitivity and 87.3% specificity [area under the curve = 0.600, 95% CI: 0.789–0.919, p < 0.001]). FMR >0.26 and FFMR <0.73 were associated with high pulmonary embolism risk. Patients with FFMI (men: 18.7–21 kg/m2, women: 14.9–17.2 kg/m2) had significantly less postoperative atrial fibrillation and wound dehiscence. Patients with FMR >0.26 and FMI >7.46 are at a 3- to 38-fold increased risk of wound dehiscence, irrespective of their BMI. Fat mass measurements were not associated with mortality. Our study demonstrates that preoperative fat mass measurements can effectively predict postoperative morbidity in CABG patients. Fat mass measurements are valuable for risk prediction, especially in non-obese patients.