Bioelectrical Impedance Analysis Identifies Patients With Worse Cardiorespiratory Fitness In Heart Failure With Reduced Ejection Fraction And Type 2 Diabetes Mellitus

Abstract

Background Cardiorespiratory fitness (CRF) is an important prognostic indicator of morbidity and mortality in patients with heart failure (HF), especially in those with comorbid type 2 diabetes mellitus (T2DM). Bioelectrical impedance analysis (BIA) is an objective and reproducible method to estimate the edema index (EI), a surrogate for extracellular volume status. Whether an increase in the EI estimated by BIA can identify patients with reduced CRF is unknown. We hypothesized that in patients with HF and reduced ejection fraction (HFrEF) and T2DM, an increased EI would inversely correlate with measures of CRF. Methods We measured peak oxygen consumption (VO2), a measure of CRF, during maximal cardiopulmonary exercise testing and the EI (percentage of extracellular water divided by total body water) with BIA in 72 patients. Subjects underwent venipuncture during the same visit to collect biomarkers. Data are reported as median and interquartile range (IQR). To determine the relationship between peak VO2 and EI, we used Spearman rank correlation and linear regression models with and without adjustments for age, sex, race, body mass index (BMI), serum creatinine, C-reactive protein (CRP), hemoglobin, NTproBNP, sodium, and comorbidities (hyperlipidemia, hypertension). Results The majority of the 72 patients were female (69%), black (47%), had age of 58 (52-62) years and median BMI of 33.9 (31.2-37.6) kg/m2. Peak VO2, EI and NTproBNP were 15.7 (12.8-18.4) mL•kg−1•min−1, 45.5 (43.8-47.9) % and 344 (111-698) pg/mL, respectively. Peak VO2 inversely correlated with EI, BMI, NTproBNP and hemoglobin at univariate analysis (R=-0.307, p Conclusion In patients with HFrEF and T2DM, edema index is an independent predictor of CRF, with a greater EI reflecting increased extracellular volume being associated with lower CRF. These findings propose that using BIA to measure the EI have potential implications from a diagnostic, prognostic and therapeutic standpoint that clearly need to be explored in future studies.