Fontan Outcomes Network: Baseline Findings From 1121 Participants

A regional, multi-center registry framework for Fontan patients: study design and early demographics

• The Fontan Outcomes Network (FON) is a collaborative learning health network spanning 38 congenital heart centers in the United States and Canada.
• The project aims to illuminate long-term trajectories after Fontan palliation for single-ventricle heart disease by capturing prospective data across a broad, multicenter cohort.

• Study type: cross-sectional analysis of individuals who underwent Fontan palliation.
• Enrollment window: August 2022 to August 2024.
• Population size and participation: 1121 participants enrolled, forming one of the largest prospective, multicenter Fontan data sets reported to date.
• Baseline scope: comprehensive collection of demographic, clinical, imaging, procedural, and medication information.
• Age stratification: analyses conducted overall and by three age groups—less than 12 years, 12 to less than 18 years, and 18 years or older.

• Most common primary diagnoses: hypoplastic left heart syndrome (about 38.5%) and right ventricular–dominant anatomy (roughly 54.9%), with distribution skewed toward younger individuals.
• Fontan configuration: extracardiac conduit emerged as the predominant Fontan type (approximately 66.8%).

• Fontan-related adverse events: documented in about 59% of participants, indicating substantial disease burden within this cohort.
• Specific events: chylous pleural effusions occurred in roughly 9.6%, Fontan-associated thrombosis in 7.1%, and nonperioperative stroke in 6.5%.
• Arrhythmia history: present in 41.3% of patients overall, with prevalence increasing with age.
• Acquired comorbidities: identified in 57.5% of participants, including asthma (12%) and sleep apnea (9%), with higher burden in older age groups.

Antidepressants were prescribed in 11.8% overall, with adult prevalence at 23.6%.

• Antithrombotic therapy: use was nearly universal across the cohort.
• Other medications: utilization varied by age, featuring beta-blockers, ACE inhibitors, and pulmonary vasodilators to differing extents.
• Mental health considerations: anxiety disorders were clinically diagnosed in 34.1% of the population, rising to 48.1% among adults.

• Significance: the network demonstrates capacity to generate robust, prospective, multi-institutional insights into Fontan circulation and associated care pathways.
• Limitations: as a cross-sectional report describing baseline characteristics, causal inferences or long-term outcomes are not provided within this dataset.