A multiple variable index and extracardiac-Fontan associated hepatic fibrosis

Background The serial follow-up of Fontan-associated liver disease is challenging, as laboratory values are frequently normal, especially with mild to moderate liver disease. Objective We investigated a composite index's correlation with hepatic biopsy total fibrosis scores in extracardiac Fontan patients. Methods We identified extracardiac Fontan patients undergoing cardiac catheterization and transvenous hepatic biopsies between June 2013 and September 2023 and liver shear wave elastography between January 2017 and July of 2023. We developed a composite index from the following: 1) elastography values, 2) sex, 3) history of a neonatal aortopulmonary shunt for pulmonary flow obstruction, 4) pacemaker, 5) Fontan duration, 6) bilirubin values, 7) univentricular dysfunction, 8) atrioventricular valvar regurgitation, 9) mean Fontan pressures, and 10) venovenous collaterals presence. We correlated the index with hepatic total fibrosis scores (0–8), the sum of pathology grading (0 to 4) performed for sinusoidal and portal fibrosis. We defined a hepatic total fibrosis score of 0–3 as none to mild and 4–8 as moderate to severe fibrosis. Results We identified 62 patients who underwent 92 transvenous liver biopsies, with 30 patients undergoing 2 biopsies. The average age at biopsy was 15 ± 2 years. We found a strong correlation (rho = 0.8, p = .00001) between liver total fibrosis scores and composite index values. A receiver operating characteristic analysis demonstrated that an index cut-off value of ≥26 predicted a total fibrosis score of ≥4 with a sensitivity of 71 % and a specificity of 75 % (AUC = 0.73, 95 % CI 0.63, 0.83, p = .0001). Conclusions We developed a composite index with a moderate predictive ability to discriminate none to mild from moderate to severe hepatic fibrosis. Nevertheless, additional data is needed to assist further validation and determine its clinical utility in the serial follow-up of Fontan associated liver disease.