Fat free mass index predicted clinical outcomes in patients with heart failure with preserved ejection fraction

Backgroud Sarcopenia, characterised by loss of muscle mass and strength, is a prevalent comorbidity in heart failure (HF) and negatively impacts patient outcomes. While sarcopenia is also recognised in heart failure with preserved ejection fraction (HFpEF), its prognostic significance in this population remains under-explored. Direct muscle volume assessment is clinically impractical due to its time-consuming nature. Purpose This study aimed to determine the association between fat-free mass index (FFMI), estimated using body fat percentage (BFP) calculated via the Deurenberg formula, and clinical prognosis in patients hospitalised for acute decompensated HFpEF. Methods We analysed data from 1210 patients (mean age 81±9 years, 54.9% female) enrolled in the PURSUIT-HFpEF study, a multicentre registry of patients hospitalised for decompensated HFpEF. BFP was estimated as 1.20 x [BMI] + 0.23 x [Age] – 16.2 for male, or as 1.20 x [BMI] + 0.23 x [Age] – 5.4 for female. Lean body mass (LBM) was calculated as body weight × (1 – BFP/100), and FFMI was derived by dividing LBM (kg) by height (m)². Patients were followed for a median of 740 days (IQR 281-1374 days) to assess major adverse cardiovascular events (MACE), a composite of death, HF hospitalisation, and stroke. Results The mean FFMI was 14.1 ± 2.1, and 1,089 patients (92.6%) had values below established sex-specific thresholds (FFMI <18 for males and <15 for females). In a stepwise Cox proportional hazards model adjusted for relevant risk factors, each 1-unit increase in FFMI was associated with a 7% reduction in the risk of MACE (hazard ratio [HR] 0.93, 95% confidence interval [CI] 0.88–0.99; p = 0.02) and a 10% reduction in all-cause mortality (HR 0.90, 95% CI 0.83–0.97; p = 0.006). Kaplan–Meier analysis demonstrated significant differences in event-free survival across FFMI quartiles (MACE: log-rank p = 0.02; all-cause death: log-rank p = 0.0001), with the lowest quartile (Q1) exhibiting a significantly higher event rate compared to the highest quartile (Q4) (MACE: p = 0.01; all-cause death: p = 0.00002)(Figure). Conclusions Low muscle mass, estimated by FFMI, is highly prevalent in patients hospitalised for acute decompensated HFpEF and was independently associated with adverse cardiovascular outcomes and mortality. FFMI may serve as a simple, clinically applicable prognostic tool in HFpEF.