Body Composition After Cardiac Transplantation via Bioimpedance Spectroscopy

Abstract

<h3>Purpose</h3> Little is known about changes in body composition and their relationships to functional status in patients following cardiac transplantation. In this prospective study, we evaluated markers of nutrition, body composition, and functional status at baseline (pre-transplant) and during the first year after cardiac transplantation. <h3>Methods</h3> Bioimpedance spectroscopy (BIS) measures electrical impedance across a spectrum of frequencies and provides estimates of fat-free mass (FFM), fat mass (FM), and phase angle (PhA) which is a direct marker of cell membrane integrity. Fifty nine adults undergoing cardiac transplantation underwent BIS, subjective global assessment (SGA) evaluation, and measurement of BMI, mid-arm muscle circumference, tricep skinfolds, handgrip strength (HGS), and 6-minute walk (6MW) at baseline and after transplantation (≤10 days, 1, 3, 6, and 12 months). <h3>Results</h3> Over one year, mean PhA and FM increased while FFM decreased (all p<0.001) (Fig 1). Functional status (HGS & 6MW) improved after transplantation (all p<0.001) (Fig 2). Among all of the markers measured, the strongest correlation was between PhA and HGS at all time points (p<0.001). There was no statistical significance noted with respect to changes in the other markers. <h3>Conclusion</h3> PhA by BIS improves in the year following cardiac transplantation. HGS and 6MW also improve after cardiac transplantation suggesting that resolution of heart failure may lead to nutrition and functional improvements. Reduction in FFM and increase in FM suggests weight gain may be associated with fat vs. lean tissue. Further research is needed to determine if these changes affect outcomes.