Determinant of functional independence in older patients with heart failure: physical function vs. muscle mass

Aim: While sarcopenia affects functional independence in older patients with heart failure (HF), the differential impact of its components-including muscle mass (MM), muscle strength (MS), and physical function (PF)-remain underexplored. We investigated these components' independent and synergistic associations with functional independence in older patients with HF, including sex-specific differences. Methods: We studied 587 older patients with HF (299 women; mean age, 79 +/- 7 years). MM, MS, and PF were assessed using dual-energy X-ray absorptiometry, handgrip strength, and physical performance tests (gait speed, five-times sit-to-stand test [FTSS], short physical performance battery [SPPB]), respectively. Cutoffs for each component followed the Asian Working Group for Sarcopenia 2019 criteria. Functional independence was assessed using the Barthel Index (BI). Results: Sarcopenia was associated with lower BI scores. Poor PF independently predicted reduced BI scores (slow gait speed: 8.4 points; prolonged FTSS: 10.9 points; low SPPB: 14.8 points; all p < 0.001), whereas low MM and weak MS did not. Low MM amplified the negative impact of poor PF on BI scores consistently across sexes. Machine-learning analysis revealed MM status-specific predictors of PF: clinical factors (female sex, HF symptoms) and comorbidities predicted poor PF in patients with normal MM; renin-angiotensin system inhibition, and cardiomyopathy were associated with preserved PF in patients with low MM. Conclusions: In older patients with HF, sarcopenia is closely and negatively associated with BI score primarily through poor PF; MM potentially modifies this relationship independent of sex. MM status-specific factors associated with PF suggest the importance of phenotype-specific approaches in facilitating functional independence.