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

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.

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.

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.

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.