Prognostic impact of respiratory sarcopenia in older patients with heart failure: a post hoc analysis from the SONIC-HF registry

AIM: Respiratory sarcopenia, characterised by reduced respiratory muscle mass and function, can impair ventilatory reserve and physical capacity, potentially worsening outcomes. However, its prevalence and prognostic significance in older patients with heart failure remain unclear. This study aimed to investigate the clinical significance of respiratory sarcopenia in this population. METHODS: This was a post hoc analysis of the compariSON of various methods In evaluatIon of sarCopenia in patients with Heart Failure (SONIC-HF) study, a multicentre prospective observational study. Among 435 patients hospitalised for heart failure (median age: 81 [interquartile range 74-85] years; 41.8% female), we defined respiratory sarcopenia as the presence of both low resting diaphragm thickness, assessed using ultrasonography, and reduced percent predicted forced vital capacity (FVC), a surrogate for respiratory muscle strength. The primary outcome was 2-year all-cause mortality. RESULTS: Respiratory sarcopenia was observed in 47 patients (10.8%). During the 2-year follow-up, 78 patients (17.9%) died. All-cause mortality was significantly higher among patients with respiratory sarcopenia than those without (P < 0.001). In Cox proportional hazards analysis, respiratory sarcopenia was independently associated with increased mortality risk (hazard ratio: 2.51; 95% confidence interval: 1.40-4.50; P = 0.002), even after adjustment for conventional risk factors. Low diaphragm thickness or reduced percent predicted FVC alone were not associated with mortality. CONCLUSIONS: In older patients with heart failure, respiratory sarcopenia was uncommon but associated with significantly higher mortality. Simultaneous assessment of respiratory muscle mass and function may aid in identifying high-risk individuals and enhance risk stratification beyond structural assessments alone.