Extra-cardiac conduit restriction is associated with increased liver fibrosis in adolescent Fontan patients.

Abstract

Objectives: To investigate the association between extra-cardiac conduit (ECC) restriction, as assessed by magnetic resonance imaging (MRI), and Fontan hemodynamics, exercise capacity, laboratory tests, and liver fibrosis in adolescent Fontan patients.

Methods: We retrospectively analyzed 93 Fontan patients who underwent fasting heart-liver MRIs between 2018 and 2022. ECC minimal diameter and cross-sectional area (CSA) were measured, and liver fibrosis was graded on delayed gadolinium enhancement sequences. Correlations between MRI and clinical/functional/laboratory data were explored using Spearman's correlation and Mann-Whitney test. Multivariable regression was performed to assess the effect of ECC size on liver fibrosis development.

Results: After a median of 10.2 (interquartile range, 8.1-12.7) years post-Fontan, ECC diameter had a median reduction of 27.3 (22.7-31.8)% from its original size. Minimal ECC diameter correlated with peak oxygen consumption (VO2) (ρ=0.324, p=0.004) and VO2 at anaerobic threshold (ρ=0.372, p=0.002). Patients with PLE exhibited smaller ECC diameters (14.0 (13.0-15.5) mm vs.16.0 (14.0-17.0) mm; p=0.020), compared to those without PLE. Patients with >mild liver fibrosis had smaller ECC diameters (14.0 (13.8-15.3) mm vs. 16.0 (15.0-17.0) mm, p<0.001), compared to those with none-mild fibrosis. At multivariable regression analysis, 1-mm increase in ECC minimal diameter decreased the risk of >mild liver fibrosis by 54.3% (odds-ratio=0.457, 95% confidence-interval: 0.264-0.791, p=0.005).

Conclusions: ECC restriction is associated with increased liver fibrosis, PLE, and reduced exercise tolerance in adolescent Fontan patients. These findings suggest that conduit upsizing strategies may be considered to alleviate hepatic congestion and improve functional capacity.