Congenital Heart Disease

1356474 - Examination of Diffuse Myocardial Fibrosis in Pediatric and Young Adult Fontan Circulation Patients

Friday, January 27, 2023

10:20 AM – 11:00 AM

Location: Pacific Jewel

Presenting Author(s)

EA

Ernie Arnouts, BSc

Medical Student
University of Colorado School of Medicine, Colorado, United States

Primary Author(s)

EA

Ernie Arnouts, BSc

Medical Student
University of Colorado School of Medicine, Colorado, United States

Co-Author(s)

AB

Alex J. Barker, PhD

Associate Professor
Children's Hospital Colorado
Chicago, Colorado, United States
Lorna P. Browne, MD

Professor of Radiology
Children's Hospital Colorado
Aurora, Colorado, United States
CG

Cesar E. Gonzalez de Alba, MD

Assistant Professor of Cardiology
Children's Hospital Colorado
Portland, Colorado, United States
LM

LaDonna J. Malone, MD

Assistant Professor of Radiology
Children's Hospital Colorado, Colorado, United States
Brian Fonseca, MD

Associate Professor of Cardiology
Children's Hospital Colorado
Aurora, Colorado, United States
MD

Michael V. DiMaria, MD

Associate Professor of Cardiology
Children's Hospital Colorado, Colorado, United States

Background: Little is known about the presence of diffuse myocardial fibrosis in patients with Fontan circulation. Given its potential association with ventricular dysfunction, diffuse fibrosis is important to investigate since many young adults with Fontan circulation are at risk of heart failure (1,2,3). Thus, this study investigates the use of T1 mapping and the computation of extracellular volume (ECV) in a cohort of 103 Fontan circulation patients as it correlates with clinical markers of cardiovascular function.

Methods: Standard of care CMR was retrospectively reviewed in healthy controls (N=50) and Fontan patients using Philips Ingenia scanners at 1.5T (N=75) and 3T (N=28). Modified Look-Locker Imaging (MOLLI) was used for T1 mapping of the short-axis through the basal, middle and apical ventricle. Participants were stratified by field strength and left vs right ventricular dominance (DLV vs DRV). Imaging was post-processed within Circle Cardiovascular Imaging (CVI42) to contour the myocardium. ECV calculations were obtained from participant hematocrit and pre- and post-contrast T1 values. Regions of interest (ROI) were used to exclude areas of high motion artifact or poor T1 fitting. Secondary variables were gathered from electronic health records (Table 1). Data from healthy individuals and Fontans was analyzed statistically with unpaired t-test of equal variance. Comparison was similarly made between DLV vs DRV. Finally, Pearson correlation coefficients were calculated for candidate variables and their respective T1 and ECV values (Table 2).

Results: Fontan data was collected from 75 patients at 1.5T and 28 patients at 3T as seen in Table 1. There was a significant increase in Fontan Native T1s vs healthy controls (1027.3 ± 54.4|982.9 ± 32.1, p < 0.0001); also seen at 3T (1287.5 ± 58.6|1254.4 ± 51.2, p 0.0483). Furthermore, the 1.5T Fontan group demonstrated a significant increase in Native T1s for DRV vs DLV (1040.3 ± 50.2|1015.3 ± 56.6, p .0482). ECVs were significantly increased at 3T (27.7 ± 3.9|23.6 ± 2, p < 0.0001) with similar but insignificant trends at 1.5T (25 ± 3.7|23.1 ± 1.9, p 0.1346). Correlation analysis was notable for a strong inverse relationship between Native T1 and VO2max at 1.5T, as well as ECV and VO2max at 3T.

Conclusion: Native T1 values were elevated in Fontan populations at 1.5T and 3T; ECV values were elevated at 3T. A trend toward increased fibrosis was observed among dominant right ventricles. The lack of statistical significance among ECV at 1.5T may be related to the limited number of controls and the varied clinical status of the Fontan groups. Additional healthy controls are being recruited to further power comparison. The most important finding is the strong relationships that were found between native T1 and ECV with the clinical correlates. For example, it is notable that increasing ECV was associated with a decreased VO2max, suggesting a possible relationship between myocardial fibrosis and decreased exercise tolerance or clinical status(4).