Sarcopenic Obesity Is Associated With Reduced Cardiorespiratory Fitness Compared With Nonsarcopenic Obesity in Patients With Heart Failure With Reduced Ejection Fraction

Background: Sarcopenia impairs cardiorespiratory fitness (CRF) in patients with heart failure with reduced ejection fraction (HFrEF). Obesity has also been shown to impair CRF; however, the effects of sarcopenia on CRF in patients with obesity and HFrEF are unknown. The aim of this analysis was to examine differences in CRF between patients with sarcopenic obesity (SO) and non-SO (NSO) with HFrEF. We also assessed associations between skeletal muscle mass index (SMMI) and CRF.

Methods: Forty patients with HFrEF and obesity underwent cardiopulmonary exercise testing to collect measures of CRF including peak oxygen consumption (VO₂), circulatory power, oxygen uptake efficiency slope, O₂ pulse, and exercise time. Body composition was performed in all patients using bioelectrical impedance analysis to quantify fat mass index and divide patients into SO and NSO based on SMMI cutoffs. Results are presented as mean (SD) or median [interquartile range] as appropriate.

Results: Nearly half (43% [n=17]) of patients had SO. Patients with SO had a lower SMMI than those with NSO, and no differences in fat mass index were observed between groups. Those with SO achieved a lower absolute peak VO₂ (NSO, 1.62±0.53 L·min^-1 versus SO, 1.27±0.44 L·min^-1, P=0.035), oxygen uptake efficiency slope (NSO, 1.92±0.59 versus SO, 1.54±0.48, P=0.036), and exercise time (NSO, 549±198 seconds versus SO, 413±140 seconds, P=0.021) compared to those with NSO. On multivariate analysis, SMMI remained a significant predictor of absolute peak VO₂ when adjusted for age, sex, adiposity, and HF severity.

Conclusions: In patients with HFrEF and obesity, sarcopenia, defined as low SMMI, is associated with a clinically significant reduction in CRF, independent of adiposity.