Extracardiac conduit restriction is associated with increased liver fibrosis in adolescent Fontan patients

The study objective was to investigate the association between extracardiac conduit restriction, as assessed by magnetic resonance imaging, Fontan hemodynamics, exercise capacity, laboratory tests, and liver fibrosis in adolescent Fontan patients.

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

After a median of 10.2 (interquartile range, 8.1-12.7) years post-Fontan, extracardiac conduit diameter had a median reduction of 27.3% (22.7%-31.8%) from its original size. Minimal extracardiac conduit diameter correlated with peak oxygen consumption (ρ = .324, P = .004) and peak oxygen consumption at anaerobic threshold (ρ = .372, P = .002). Patients with protein-losing enteropathy exhibited smaller extracardiac conduit diameters (14.0 [13.0-15.5] mm vs 16.0 [14.0-17.0] mm; P = .020) compared with those without protein-losing enteropathy. Patients with more than mild liver fibrosis had smaller extracardiac conduit diameters (14.0 [13.8-15.3] mm vs 16.0 [15.0-17.0] mm, P < .001) compared with those with none-mild fibrosis. At multivariable regression analysis, 1-mm increase in extracardiac conduit minimal diameter decreased the risk of more than mild liver fibrosis by 54.3% (odds ratio, 0.457, 95% CI, 0.264-0.791, P = .005).

Extracardiac conduit restriction is associated with increased liver fibrosis, protein-losing enteropathy, 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.