1. Bioelectric impedance analysis-measured edema index (EI) is a feasible, non-invasive technique for measuring fluid overload.
2. EI is an independent predictor of cardiorespiratory fitness in heart failure patients with reduced ejection fraction and type 2 diabetes mellitus.
Evidence Rating Level: 2 (Good)
One of the prominent features of heart failure (HF) is fluid overload, which is difficult to measure in a noninvasive manner. However, the edema index (EI), a surrogate for extracellular volume status, can be estimated with bioelectrical impedance analysis. This cross-sectional study investigated the relationship between EI and cardiorespiratory fitness (CRF) in patients with HF with reduced ejection fraction (EF) and type 2 diabetes mellitus. Measures included peak oxygen consumption, exercise time, serum creatinine, C-reactive protein, hemoglobin, NT-proBNP, and sodium. A quality of living measure (Minnesota Living With HF Questionnaire) was also used. A total of 72 patients (median [IQR] age = 58 [52-62] years, 69% female, 47% Black) were included in this study. Approximately 88% of this sample had hypertension and 77% had hyperlipidemia. Median body mass index (BMI) was 33.9 kg/m2 (IQR 31.2 to 37.6). Men demonstrated a higher median EI than their female counterparts (p = .013) and Black participants had significantly greater EI than White participants (p = .020). EI was positively associated with BMI (ρ = .388; p = .001) and negatively associated with age (ρ = -.239; p = .040), serum creatinine (ρ = -.296; p = .011), and hemoglobin (ρ = -.329; p = .004). Using univariate quantile regression, each 1% absolute increase in EI was associated with a decrease in median peak VO2 (β = −0.613; 95% CI −0.885 to −0.340; p<.001), and a significant decrease in median exercise time in seconds (β = −24.0; 95% CI −35.3 to −12.7; p<.001). Greater EI was also associated with worse functional capacity, as a measure of exercise time. Overall, and in spite of a relatively small sample size, this study demonstrated that bioelectrical impedance analysis, to measure EI, can be an effective tool in predicting CRF in individuals with HF and type 2 diabetes mellitus.
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