Alternative Measures of Body Composition and Outcomes Following Heart Transplant

Current guidelines for heart transplant (HT) listing support body mass index (BMI) < 35 kg/m², though data supporting this recommendation is mixed. It is unclear if other more specific measurements of body composition are better predictors of outcomes post-HT. This retrospective study included patients who underwent HT between 2014 and 2019 and underwent an abdominal CT scan within 3 months of HT. Tissue characterization was performed using Slice-O-Matic software to derive measurements including BMI, fat mass index (FMI), visceral adipose tissue to subcutaneous adipose tissue ratio (VAT/SAT), fat free mass index (FFMI), and skeletal muscle index (SMI). Univariate and multivariate logistic regression analyses were used to investigate association of body composition variables by tertiles to 1 year mortality, readmission, primary graft dysfunction, length of stay, infection, and renal failure. Of the 104 patients, 80% were male and 56% were Caucasian. Highest and lowest BMI tertiles were significantly associated with an increased risk of hospital readmission within 1 year post HT (OR 3.4, [95%CI 1.1-11.4]; OR 5.9, [95% CI 1.7-25.1]; p = 0.01) as well as an increased risk of infections requiring hospitalization (OR 3.2, [95% CI 1.2-9.0]; OR 3.9, [95%CI 1.4-11.7]; p = 0.02). FMI, VAT/SAT, FFMI, and SMI were not associated with outcomes 1-year post-HT. Highest and lowest BMI tertiles were associated with increased rates of hospital readmission and infection in the first-year post HT, while other measurements of body composition were not associated with any poor outcomes post-HT. Although BMI does not predict mortality post-HT, it can differentiate risk better than all other metrics.