Surveillance of Fontan Associated Liver Disease in Childhood and Adolescence

Epidemiology of Fontan-associated liver disease in Japan: Results from a nationwide survey in 2021

AIM

Although the Fontan procedure has improved the survival of patients with single-ventricle heart disease, the long-term consequences of the procedure have been a concern. This study aimed to explore the patients' postoperative clinical characteristics, including a diagnosis of Fontan-associated liver disease (FALD).

METHODS

A nationwide Japanese epidemiological survey of post-Fontan patients was undertaken in 2021. The survey targets were selected from all departments of pediatrics, pediatric surgery, cardiology, cardiovascular surgery, and gastroenterology using stratified random sampling by the number of beds. Each department was asked to complete a mail-back questionnaire on the numbers of patients and their clinical characteristics. The diagnosis of FALD was made by each attending physician.

RESULTS

The estimated number of post-Fontan patients was 7810 (95% confidence interval, 5430-10 200) in 2020, with a period prevalence of 61.9 per million. During the follow-up of 13.8 years after the Fontan procedure, 40% of patients were diagnosed with FALD. An elevated γ-glutamyl transpeptidase level was the most common finding leading to the FALD diagnosis (41%), and 45% of the patients also showed liver fibrosis. Compared with non-FALD patients, FALD patients were older, had longer duration since the Fontan procedure, and had more severe cardiac or liver conditions. However, more than half of the non-FALD patients had elevated liver enzyme levels, suggesting underestimation of the number of FALD patients.

CONCLUSIONS

In 2020, approximately 40% of post-Fontan patients underwent follow-up with a diagnosis of FALD, although the lack of established diagnostic criteria for FALD could affect the reported prevalence of FALD.

EASL-ERN position paper on liver involvement in patients with Fontan-type circulation

Fontan-type surgery is the final step in the sequential palliative surgical treatment of infants born with a univentricular heart. The resulting long-term haemodynamic changes promote liver damage, leading to Fontan-associated liver disease (FALD), in virtually all patients with Fontan circulation. Owing to the lack of a uniform definition of FALD and the competitive risk of other complications developed by Fontan patients, the impact of FALD on the prognosis of these patients is currently debatable. However, based on the increasing number of adult Fontan patients and recent research interest, the European Association for The Study of the Liver and the European Reference Network on Rare Liver Diseases thought a position paper timely. The aims of the current paper are: (1) to provide a clear definition and description of FALD, including clinical, analytical, radiological, haemodynamic, and histological features; (2) to facilitate guidance for staging the liver disease; and (3) to provide evidence- and experience-based recommendations for the management of different clinical scenarios.

Non-contrast enhanced magnetic resonance imaging for characterization of Fontan associated liver disease

OBJECTIVES

To evaluate the ability of non-contrast enhanced magnetic resonance imaging (MRI) techniques to characterize Fontan associated liver disease (FALD) in adolescent and adult Fontan patients.

METHODS

Fontan patients (n = 29) and healthy controls (n = 13) underwent an MRI protocol with T₁, T₂ and Apparent Diffusion Coefficient (ADC) mapping. Routine FALD screening included abdominal ultrasound and laboratory testing.

RESULTS

Median follow-up after Fontan operation was 15.1 (IQR 12.0-16.8) years. Distinct differences in tissue characteristics were visualized. T₁ and T₂ relaxation times were prolonged in Fontan patients, particularly of the right lobe (T₁: 745 (IQR 715-784) ms vs. 586 (IQR 555-602) ms, p < 0.001; T₂: 63 (IQR 59-64) ms vs. 58 (IQR 56-60) ms, p = 0.002). Left lobe ADC was lower in Fontan patients (1.10 (IQR 1.06-1.18) x 10^-3 mm²/s vs. 1.23 (IQR 1.19-1.29) x 10^-3 mm²/s, p < 0.001). T₂ mapping was able to differentiate between controls and Fontan patients with different FALD severity. Right lobe T₂ was higher in patients with moderate or severe in comparison to those with no or mild changes and healthy controls (64 (IQR 61-67) ms vs. 60 (IQR 59-63) ms vs. 58 (IQR 56-60) ms, p = 0.001).

CONCLUSIONS

Non-contrast enhanced MRI methods are able to visualize regional differences in liver tissue characteristics. T₁ and T₂ relaxation times were prolonged in Fontan patients suggestive of fibrosis or congestive hepatopathy, while reduced ADC might reflect impaired microperfusion. These methods have promising clinical potential for detection of liver abnormalities in Fontan patients. The usefulness of T₂ mapping to grade FALD severity merits further investigation.