Axial Muscle Size as a Strong Predictor of Death in Subjects With and Without Heart Failure

BACKGROUND: The impact of skeletal muscle size, quantified using simple noninvasive images routinely obtained during cardiac magnetic resonance imaging studies on mortality in the heart failure (HF) population is currently unknown. METHODS AND RESULTS: We prospectively enrolled 567 subjects without HF (n=364), with HF with reduced ejection fraction (n=111), or with HF with preserved ejection fraction (n=92), who underwent a cardiac magnetic resonance imaging. Skeletal muscle cross‐sectional area was assessed with manual tracing of major thoracic muscle groups on axial chest magnetic resonance images. Factor analysis was used to identify a latent factor underlying the shared variability in thoracic muscle cross‐sectional area. Cox regression was used to assess the relationship between these measurements and all‐cause mortality (median follow up, 36.4 months). A higher overall thoracic muscle area factor assessed with principal component analysis was independently associated with lower mortality (standardized hazard ratio, 0.51; P<0.0001). The thoracic muscle area factor was predictive of death in subjects with HF with preserved ejection fraction, HF with reduced ejection fraction, and those without HF. Among all muscle groups, the pectoralis major cross‐sectional area was the most representative of overall muscle area and was also the most robust predictor of death. A higher pectoralis major cross‐sectional area predicted a lower mortality (standardized hazard ratio, 0.49; P<0.0001), which persisted after adjustment for various confounders (standardized hazard ratio, 0.55; P=0.0017). CONCLUSIONS: Axial muscle size, and in particular smaller size of the pectoralis major, is independently associated with higher risk of mortality in patients with and without HF. Further work should clarify the role of muscle wasting as a therapeutic target in patients with HF.