Abstract 15268: Development of a Reliable Means of Assessment of Liver Function After the Fontan Operation: Dual Cholate Clearance Assay

Abstract

Introduction: Currently there is no biomarker or test to accurately measure liver function in Fontan-associated liver disease. The dual cholate test (HepQuant SHUNT) is a noninvasive, flow-dependent assay measuring hepatic clearance of a bile acid, cholate, and may serve as a useful measure of liver function in the Fontan. We aim to measure cholate clearance in a cohort of Fontan patients and compare to normal controls. Methods: Single center, prospective pilot study of Fontan patients ≥ 18 years. Hepatic clearance of orally administered d4-cholate and intravenously administered 13C-cholate were measured in peripheral venous samples after 5, 20, 45, 60, and 90 minutes. Portal hepatic filtration rate (HFR), systemic HFR, shunt fraction (systemic HFR/portal HFR), and disease severity index (DSI) were calculated. Decline in HFRs and increase in shunt fraction or DSI is indicative of impaired liver function. Two-sided t-tests were used to compare values between Fontans and controls. Results: Twelve Fontan patients were enrolled (33% female, median age 29.9 [range 23.6 - 41.0] years). Median total bilirubin was 0.8 (range 0.3-2.1) mg/dL, AST 30.5 (range 16-55) U/L, ALT 32 (range 11-53) U/L, alkaline phosphatase 87 (range 42-191) U/L and platelets 177 (range 130-428) 10 3 /μL. Mean cardiac index was 3.0 ± 0.5 L/min/m 2 . Cholate clearance was lower in Fontans compared to controls (Figure). Mean portal HFR (mL/min/kg) in Fontans was lower than controls (15.1 ± 10.9 vs 29.1 ± 9.0; p<0.001) as well as systemic HFR (3.7 ± 1.3 vs 6.5 ± 1.5; p<0.001) whereas shunt fraction (%) was not (29.2 ± 11.4 vs 24.1 ± 7.5; p=NS). DSI was higher in Fontans compared to controls (19.4 ± 6.1 vs 9.2 ± 3.4; p<0.001). Conclusions: Fontan patients demonstrate reduced hepatic function compared to normal controls but there is considerable variability. Future studies using the dual cholate test will examine the relationship between liver and cardiac function, as well as risk of adverse clinical outcome, in the Fontan.