Role of Fat-Free Mass-Adjusted Cardiorespiratory Fitness in Predicting Hospitalization Risk in Patients with Heart Failure

Abstract

Purpose: Reduced cardiorespiratory fitness (CRF) is associated with hospitalization risk in heart failure (HF). Traditional peak oxygen uptake (VO2) scaling uses total body weight (TBW), potentially underestimating CRF due to adiposity. The prognostic value of fat-free mass (FFM)-adjusted peak VO2 remains unclear, particularly in Asian populations. Materials and Methods: A retrospective cohort study included HF patients who underwent cardiopulmonary exercise testing and bioelectrical impedance analysis. Two peak VO2 cutoffs-14 mL/TBW kg/min and 19 mL/FFM kg/min-were applied to predict all-cause and HF-specific 1-year hospitalization. The prognostic performance was assessed using Cox proportional hazards models adjusted for the Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) risk score. Likelihood ratio tests were conducted to evaluate the incremental value of adding the FFM-adjusted cutoff. Results: A total of 83 patients (mean age, 60.0 years; 14 female; 37 obese) were analyzed. Both TBW-and FFM-adjusted cutoffs were significantly associated with increased risk of all-cause hospitalization [hazard ratio (HR)=3.86, 95% confidence interval (CI), 1.40-10.63 vs. HR=5.02, 95% CI, 1.98-12.72] and HF-specific hospitalization (HR=4.00, 95% CI, 1.00-16.05 vs. HR=7.26, 95% CI, 1.92-27.46). Adding the FFM-adjusted cutoff significantly improved model fit when added to a model with the TBW-adjusted cutoff (p<0.05). The difference in c-indices between the two cutoffs after bootstrapping was not statistically significant. Conclusion: The FFM-adjusted cutoff can complement the traditional TBW-adjusted cutoff by correcting the confounding bias of excessive adiposity or low muscle mass, providing incremental prognostic value for risk stratification in Asian patients with HF.