Fat Mass and Cause-Specific Death in Older Patients with Heart Failure

Prior studies in patients with heart failure (HF) have reported inconsistent associations between fat mass and mortality, but they did not account for heterogeneity in causes of death. We evaluated whether higher fat mass relates differently to cardiovascular (CV) and non-CV death in older patients with HF.

We performed a secondary analysis of the multicentre FRAGILE-HF (Prevalence and prognostic value of physical and social frailty in geriatric patients hospitalized for heart failure) cohort, including patients aged ≥ 65 years hospitalized for decompensated HF. Fat mass was measured by bioelectrical impedance and indexed as fat mass index (FMI, kg/m²). Patients were stratified by sex-specific tertiles (low-FMI, middle-FMI, high-FMI). Outcomes were all-cause death, CV death, and non-CV death within 2 years. Kaplan-Meier curves with log-rank tests and Cox models assessed associations with mortality.

In total, 1332 patients were enrolled, and 900 were analyzed (median age, 81 years [interquartile range, 74-86]; 57.6% men). During the follow-up period, 171 deaths occurred, including 95 CV deaths and 76 non-CV deaths. Using low-FMI as the reference category, all-cause death was significantly lower in those with high-FMI (hazard ratio [HR] 0.60, 95% confidence interval [CI] 0.40-0.89; P = 0.011). For cause-specific death, CV death was significantly lower in high-FMI (HR 0.33, 95% CI 0.18-0.60; P < 0.001), although non-CV death did not differ in middle-FMI (HR 0.81, 95% CI 0.47-1.40; P = 0.444) or high-FMI (HR 0.89, 95% CI 0.52-1.54; P = 0.685).

Higher FMI is linked to a lower risk of CV death but not non-CV death, indicating that its prognostic value depends on cause of death.