S5915 The Hidden Burden of Fontan-Associated Liver Disease: Unmasking a Predictable Pathophysiologic Pattern – A Case Report

Introduction: The Fontan procedure, a palliative surgical intervention for single-ventricle congenital heart defects, redirects systemic venous return directly to the pulmonary arteries. While it improves survival in patients with complex congenital heart disease, it predisposes patients to Fontan-associated liver disease (FALD), a spectrum of hepatic abnormalities ranging from congestion and fibrosis to cirrhosis and hepatocellular carcinoma (HCC). Case Description/Methods: A 23-year-old woman with congenital tricuspid atresia and hypoplastic right ventricle, status post-Fontan procedure at age 3, presented with fever, chills, abdominal pain, and dysuria. She had been recently treated for a urinary tract infection. Laboratory studies revealed elevated liver enzymes (alkaline phosphatase 163 U/L, aspartate aminotransferase 79 U/L, alanine aminotransferase 84 U/L), with a normal white blood cell count and stable hemodynamics. Imaging revealed hepatosplenomegaly, nodular liver contour, ascites, and elevated liver stiffness (13.3 kPa on elastography), suggestive of advanced chronic liver disease. MRCP showed no biliary obstruction or discrete lesions. Workup for other causes of cirrhosis including viral and autoimmune hepatitis was negative except for anti-smooth muscle antibody positivity. At this time, a diagnosis of congestive hepatopathy due to elevated right heart pressures was favoured. Patient was referred to tertiary care center for right heart cath and further evaluation for liver transplant. Discussion: FALD is driven by chronic hepatic congestion due to elevated central venous pressure in Fontan physiology, leading to sinusoidal dilation, fibrosis, and ultimately cirrhosis. This condition is being increasingly recognized as a cause of liver cirrhosis especially as the burden of Fontan procedure continues to go up. The progression is often subclinical, with preserved liver function until late stages. In this case, liver disease was incidentally discovered during workup for unrelated symptoms. This underscores the need for heightened clinical vigilance and routine hepatic monitoring in Fontan patients, even when asymptomatic. The absence of specific serologic markers and often non-distinctive clinical presentation necessitate a high index of suspicion, with imaging and elastography playing key roles in diagnosis. Early recognition is crucial for guiding management, preventing complications, and assessing transplant candidacy when appropriate.