Patients with Higher Fat Mass Have Longer Survival in Heart Failure

Abstract

Background: Obesity is commonly thought of as a risk factor for heart failure (HF); however studies have shown that higher body mass index (BMI) and waist circumference (WC) are associated with improved prognosis in HF. This has been termed the obesity paradox. However, the role of body composition components such as lean body mass (LBM) and body fat mass (BFM) is unknown. Hypothesis: Using bioelectrical impedance analysis (BIA) to assess body composition in HF will help determine whether fat and/or lean mass are contributing to the obesity paradox. Methods: BIA assessment of body composition in 354 HF patients was performed using InBody 520 (Biospace Inc, CA), an 8-point tactile electrode system employing 5, 50, and 500 kHz . BFM and LBM were indexed by body surface area (BSA). The cohort was stratified based on median BFM indexed to BSA (BFMi, 12.5 kg/m) and LBM indexed to BSA (LBMi, 28.9 kg/m). Results: The mean age of patients studied was 56614 and the mean LVEF was 386 16. Baseline characteristics between all groups were compared and were similar (see Table below). When comparing 2 year survival from urgent transplant or death, patients with higher BFMi had improved survival over patients with lower BFMi (96% vs. 87%, p.005). There was a trend towards improved 2 year event free survival of patients with higher LBMi when compared to patients with lower LBMi, however this was not significant (93% vs. 90%, p 0.5). Two year survival was also compared in the following 4 categories of body composition: a combination of low LBMi and LBFMi (85.1%), low LBMi and high BFMi (94%), high LBMi and low BFMi (89%) and high LBMi and BFMi (100%, p 0.036). The low LBMi and BFMi category trended towards worse survival; whereas the high LBMi and BFMi category trended towards a better 2 year survival. Conclusions: Our data suggest that while higher fat mass is protective in HF, higher lean mass may be protective in HF, but not significantly. Our data also suggest that a body composition of low LBMi and low BFMi is the least protective in HF, whereas high LBMi and high BFMi is most protective in HF. For a more complete understanding of the obesity paradox in HF, further investigations of body composition and outcomes in HF are warranted.