RESUMO
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 .
