Fontan-associated liver disease: pathophysiology, investigations, predictors of severity and management

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.

Intrahepatic transcriptomics differentiate advanced fibrosis and clinical outcomes in adults with the Fontan circulation

Background

The molecular mechanisms underlying Fontan associated liver disease (FALD) remain largely unknown. We aimed to assess intrahepatic transcriptomic differences among patients with FALD according to the degree of liver fibrosis and clinical outcomes.

Methods

This retrospective cohort study included adults with the Fontan circulation at the Ahmanson/UCLA Adult Congenital Heart Disease Center. Clinical, laboratory, imaging and hemodynamic data prior to the liver biopsy were extracted from medical records. Patients were classified into early (F1-F2) or advanced fibrosis (F3-F4). RNA was isolated from formalin-fixed paraffin embedded liver biopsy samples; RNA libraries were constructed using rRNA depletion method and sequencing was performed on Illumina Novaseq 6000. Differential gene expression and gene ontology analyses were carried out using DESeq2 and Metascape. Medical records were comprehensively reviewed for a composite clinical outcome which included decompensated cirrhosis, hepatocellular carcinoma, liver transplantation, protein-losing enteropathy, chronic kidney disease stage 4 or higher, or death.

Results

Patients with advanced fibrosis had higher serum BNP levels and Fontan, mean pulmonary artery and capillary wedge pressures. The composite clinical outcome was present in 23 patients (22%) and was predicted by age at Fontan, right ventricular morphology and presence of aortopulmonary collaterals on multivariable analysis. Samples with advanced fibrosis had 228 up-regulated genes compared to early fibrosis. Samples with the composite clinical outcome had 894 up-regulated genes compared to those without it. A total of 136 up-regulated genes were identified in both comparisons and these genes were enriched in cellular response to cytokine stimulus, response to oxidative stress, VEGFA-VEGFR2 signaling pathway, TGF-beta signaling pathway, and vasculature development.

Conclusions

Patients with FALD and advanced liver fibrosis or the composite clinical outcome exhibit up-regulated genes including pathways related to inflammation, congestion, and angiogenesis. This adds further insight into FALD pathophysiology.

Fontan-associated liver disease: Diagnosis, surveillance, and management

The Fontan operation is a lifesaving procedure for patients with functional single-ventricle congenital heart disease, where hypoplastic left heart syndrome is the most frequent anomaly. Hemodynamic changes following Fontan circulation creation are now increasingly recognized to cause multiorgan affection, where the development of a chronic liver disease, Fontan-associated liver disease (FALD), is one of the most important morbidities. Virtually, all patients with a Fontan circulation develop liver congestion, resulting in fibrosis and cirrhosis, and most patients experience childhood onset. FALD is a distinctive type of congestive hepatopathy, and its pathogenesis is thought to be a multifactorial process driven by increased nonpulsatile central venous pressure and decreased cardiac output, both of which are inherent in the Fontan circulation. In the advanced stage of liver injury, complications of portal hypertension often occur, and there is a risk of developing secondary liver cancer, reported at young age. However, FALD develops with few clinical symptoms, a surprisingly variable degree of severity in liver disease, and with little relation to poor cardiac function. The disease mechanisms and modifying factors of its development are still not fully understood. As one of the more important noncardiac complications of the Fontan circulation, FALD needs to be diagnosed in a timely manner with a structured monitoring scheme of disease development, early detection of malignancy, and determination of the optimal time point for transplantation. There is also a clear need for consensus on the best surveillance strategy for FALD. In this regard, imaging plays an important role together with clinical scoring systems, biochemical workups, and histology. Patients operated on with a Fontan circulation are generally followed up in cardiology units. Ultimately, the resulting multiorgan affection requires a multidisciplinary team of healthcare personnel to address the different organ complications. This article discusses the current concepts, diagnosis, and management of FALD, with special emphasis on the role of different imaging techniques in the diagnosis and monitoring of disease progression, as well as current recommendations for liver disease surveillance.

Fontan Hepatopathy - Managing Unknowns

BACKGROUND AND AIMS

How to best monitor Fontan associated liver disease (FALD) remains unclear. We describe results from a prospective liver care pathway in adults (n=84) with a Fontan circulation.

METHODS

Routine assessment of the liver, by acoustic radiation force frequency and ultrasound was undertaken. Results, including liver biochemistry, systemic ventricular function (echocardiography), functional class, medication use and clinical endpoints (varices, hepatocellular carcinoma, heart transplantation and death) were collated.

RESULTS

Most individuals returned a cirrhotic range acoustic radiation force impulse imaging (ARFI) result. ARFI values were greater in the proportion of individuals with hepatic nodularity (p=0.024). Univariate analysis demonstrated moderate correlation with platelet number (Spearmans rho= -0.376, p=0.049). Patients with clinical endpoints had lower platelets (p=0.012) but only a trend to hepatic nodularity (p=0.057). Clinical endpoints were more common in those with ventricular dysfunction (p=0.011). Multivariate analysis revealed that age at Fontan and being on angiotensin converting enzyme inhibitors (ACEI) predicted ARFI score (β=0.06 (95% CI 0.01-0.09), p=0.007 and β=0.53 (95% CI 0.17-0.89), p=0.005, respectively). However, these associations were not significant once adjusted for Fontan type, age at ARFI, systemic ventricle morphology, ventricle function, or Model for End-stage Liver Disease (MELD-XI) excluding international normalised ratio (INR) (p>0.05 for all).

CONCLUSIONS

Ideal FALD monitoring remains unclear. ARFI has utility as a binary non-invasive indicator of cirrhosis, highlighting individuals who may need more frequent ongoing monitoring for hepatocellular carcinoma. However, no definite advantage to serial ARFI, once cirrhotic range ARFI results are present, has been identified.

Alcohol use is prevalent among adults with the fontan circulation but does not correlate with liver disease

Background

Alcohol consumption is associated with an increased risk of liver disease. There are limited studies on the epidemiology of alcohol use and its effects on Fontan-associated liver disease (FALD) in adulthood.

Methods

In this single-center prospective cohort study, patients were enrolled from the Fontan clinic between November 2019 and November 2020, excluding those with chronic hepatitis C or B. Alcohol consumption was quantified by Alcohol Use Disorders Identification Test (AUDIT) questionnaire and a supplementary questionnaire. Participants were stratified into alcohol consumers and non-consumers. Alcohol consumption was correlated to the magnitude of fibrosis on liver biopsy and the varices, ascites, splenomegaly, and thrombocytopenia (VAST) score.

Results

Forty-three patients (age 30 ​± ​6.5 years) were enrolled, and most were in NYHA FC 1 or 2. Twenty-six (60.5%) participants consumed alcohol regularly in the past year (twenty with low-risk consumption and six with hazardous consumption). Alcohol consumers were more likely to have better NYHA FC. Of those, half reported alcohol consumption for longer than one year before enrollment. Eleven (25.6%) participants reported underage drinking. After multivariable adjustment, male sex was associated with increased severity of liver fibrosis (OR 3.7 [1.0 to 13.6]). Alcohol consumption was not associated with liver fibrosis (OR 1.2 [0.3 to 4.9]) or VAST scores (OR 1.2 [0.01 to 2.2]).

Conclusions

Alcohol consumption is prevalent among adults with the Fontan circulation but does not correlate with FALD. However, further studies are required to validate the results in cohorts with heavier alcohol consumption. Underage drinking was prevalent and warrants screening in pediatrics.

Non-invasive biomarkers of Fontan-associated liver disease

Background & Aims

Fontan-associated liver disease (FALD) has emerged as an important morbidity following surgical palliation of single ventricle congenital heart disease. In this study, non-invasive biomarkers that may be associated with severity of FALD were explored.

Methods

A retrospective cohort of paediatric patients post-Fontan who underwent liver biopsy at a high volume at a paediatric congenital heart disease centre was reviewed.

Results

Among 106 patients, 66% were male and 69% were Hispanic. The mean age was 14.4 ± 3.5 years, and biopsy was performed 10.8 ± 3.6 years post-Fontan. The mean BMI was 20.8 ± 5 kg/m², with 27.4% meeting obesity criteria. Bridging fibrosis was observed in 35% of patients, and 10.4% of all patients had superimposed steatosis. Bridging fibrosis was associated with lower platelet counts (168.3 ± 58.4 vs. 203.9 ± 65.8 K/μl for congestive hepatic fibrosis score [CHFS] 0–2b, p = 0.009), higher bilirubin (1.7 ± 2.2 vs. 0.9 ± 0.7 mg/dl, p = 0.0090), higher aspartate aminotransferase-to-platelet ratio index [APRI] and fibrosis-4 [FIB-4] scores (APRI: 0.5 ± 0.3 vs. 0.4 ± 0.1, p <0.01 [AUC: 0.69] and FIB-4: 0.6 ± 0.4 vs. 0.4 ± 0.2, p <0.01 [AUC: 0.69]), and worse overall survival (median 2 years follow-up post-biopsy, p = 0.027). Regression modelling of temporal changes in platelet counts before and after biopsy correlated with fibrosis severity (p = 0.005).

Conclusions

In this large, relatively homogeneous adolescent population in terms of age, ethnicity, and Fontan duration, bridging fibrosis was observed in 35% of patients within the first decade post-Fontan. Bridging fibrosis was associated with worse survival. Changes in platelet counts, even years before biopsy, and APRI/FIB-4 scores had modest discriminatory power in identifying patients with advanced fibrosis. Steatosis may represent an additional risk factor for disease progression in obese patients. Further prospective studies are necessary to develop strategies to screen for FALD in the adolescent population.

Lay summary

In this study, the prevalence of Fontan-associated liver disease (FALD) in the young adult population and clinical variables that may be predictive of fibrosis severity or adverse outcomes were explored. Several lab-based, non-invasive markers of bridging fibrosis in FALD were identified, suggesting that these values may be followed as a prognostic biomarker for FALD progression in the adolescent population.

•

FALD is universal within 10 years post-Fontan, with 35% of patients having bridging fibrosis.

•

Of our adolescent patient population, 10% had concomitant hepatic steatosis, which was associated with obesity.

•

Regression modelling demonstrates that temporal changes in platelet counts correlate with severity of fibrosis in FALD.

•

AST-to-platelet ratio index and FIB-4 scores correlate with bridging fibrosis with a high specificity.

•

Bridging fibrosis in FALD is associated with worse survival.

MR imaging features and long-term evolution of benign focal liver lesions in Budd-Chiari syndrome and Fontan-associated liver disease

PURPOSE

To compare the magnetic resonance imaging (MRI) features of benign liver lesions developed on Budd-Chiari syndrome (BCS) with those on Fontan-associated liver disease (FALD) and to describe their long-term progression.

MATERIALS AND METHODS

Patients with BCS or FALD who underwent MRI between 2010 and 2020 were retrospectively included. MRI features of nodules (≥ 5 mm) at baseline and at final follow-up were reviewed. The final diagnosis of benign lesion was based on a combination of clinical and biological data and findings at follow-up MRI examination.

RESULTS

Two-hundred and thirty benign liver lesions in 39 patients with BCS (10 men, 29 women; mean age, 36 ± 11 [SD] years; age range: 15-66 years) and 84 benign lesions in 14 patients with FALD (2 men, 12 women; mean age, 31 ± 10 [SD] years; age range: 20-48 years) were evaluated. On baseline MRI, BCS nodules were more frequently hyperintense on T1-weighted (183/230, 80%) and hypointense on T2-weighted (142/230; 62%) images, while FALD nodules were usually isointense on both T1- (70/84; 83%) and T2-weighted (64/84; 76%) images (all P< 0.01). Most lesions showed arterial phase hyperenhancement (222/230 [97%] vs. 80/84 [95%] in BCS and FALD, respectively; P = 0.28) but wash-out was more common in BCS (64/230 [28%] vs. 9/84 [11%]; P < 0.01). At follow-up, changes were more frequent in BCS nodules with more frequent disappearance (P < 0.01), changes in size, signal intensity on T2-weighted, portal, and delayed phase, and in the depiction of washout and capsule (all P ≤ 0.03).

CONCLUSION

MRI features of benign lesions are different at diagnosis and during the course of the disease between BCS and FALD. Changes in size and MRI features are more frequent in benign lesions developed in BCS.