Abstract 15864: Measured versus Estimated Resting Metabolic Rate in Heart Failure With Preserved Ejection Fraction

Abstract

Introduction: Obesity is common in heart failure with preserved ejection fraction (HFpEF) and dietary weight loss can improve functional capacity, but sarcopenia and frailty are also frequently present. Little evidence is available regarding resting metabolic rate (RMR) or how commonly used equations to estimate RMR compare to measured RMR in HFpEF. This information is vital for counseling patients on individual caloric needs. Hypothesis: Commonly used estimation equations do not accurately reflect measured RMR in patients with HFpEF. Methods: Resting metabolic rate (RMR) was measured with a metabolic cart for consecutive patients with HFpEF (EF ≥50%) referred for right heart catheterization at the University of Michigan from 2011-2015. Patients with congenital, infiltrative, hypertrophic, or restrictive cardiomyopathy were excluded. The RMR was calculated using the Weir formula: RMR= 1440*[3.94 VO 2 (l/min) + 1.11*VCO 2 (l/min)] kcal/day. Measured RMR and estimations of RMR using the Harris Benedict Equation (HBE), Mifflin-St Jeor Equation (MSJE), and World Health Organization (WHO) equation were compared using paired t-tests and Bland-Altman plots. Results: Patients (n=43) were aged (mean ± SD) 62 ± 11.6 years, 53% female, and BMI 34.9 ± 11. Mean measured RMR from Weir equation was 1514 ± 479 kcal/day. Estimated RMR by HBE was 1784 ± 530, MSJE was 1685 ± 457, and WHO equation was 1816.8 ± 485 kcal/day. All estimations significantly overestimated RMR when compared to the Weir method (>10% difference and p<0.01 for all; Figure A-C). The MSJE had the closest range of agreement to the measured RMR. Conclusions: Estimations of resting metabolic rate in patients with HFpEF demonstrated a fixed bias towards overestimation when compared to measured RMR by metabolic cart. Given HFpEF populations are often obese and are counseled routinely on weight loss, understanding the implicit bias of equations estimating RMR is vital when providing nutritional and dietary counseling.