Abstract 15302: Cardiac MRI Assessment of Cardiac Output Agrees With Simultaneous Fick Assessment in Pediatric Heart Transplant Patients

Abstract

Introduction: Systemic cardiac output (Qs) and pulmonary blood flow (Qp) can be measured by cardiac magnetic resonance (CMR) and invasive oximetry, with studies showing good agreement between the two modalities. CMR-guided right heart catheterization (MR-RHC) collects simultaneous CMR and oximetry measurements permitting direct comparison. This study assessed agreement between CMR and Fick measurements of cardiac output in the pediatric heart transplant (HT) population. Methods: Twenty-three pediatric HT patients (body surface area range 0.6-2 m 2 ) with 53 MR-RHC between 2014 -2020 were reviewed. One outlier was excluded due to erroneous pulmonary vein saturation, leaving 52 MR-RHC for analysis. Measurements of un-indexed Qs and Qp from both CMR phase contrast and invasive oximetry using Fick were collected. Bland-Altman (BA) statistical and graphical analyses compared CMR versus Fick estimates of Qs and Qp. Results: BA limits of agreement (LOA) and corresponding concordance plot demonstrate good agreement between CMR and Fick (Figure 1). Panels A and B are the BA and concordance plots for Qs, respectively. Panels C and D are the BA and concordance plots for Qp, respectively. The 95% confidence interval LOA are -1.0 to +1.8 for Qs and -1.0 to +1.7 for Qp. Average bias and Lin correlation are similar for Qs and Qp at +0.36 L/min and 0.8, respectively. Conclusions: CMR and Fick measurements of Qs and Qp are similar in pediatric HT patients, with a tendency for slightly higher values by Fick estimates and similar LOA to previously published results. CMR acquired hemodynamics offer a radiation-free modality to reduce overall radiation exposure for pediatric HT patients.