This large, long-term registry shows that ECC Fontan confers a lower arrhythmia risk than LT or AP, and arrhythmias serve as a marker of Fontan failure and mortality in post-Fontan patients.
Arrhythmias occurred in 13.3% of Fontan patients at a median age of 17.3 years, with tachyarrhythmias more common than bradyarrhythmias.
At 20 years post-Fontan, freedom from any arrhythmia, tachyarrhythmia, and bradyarrhythmia was 82.5%, 86.9%, and 90.5%, respectively.
Atriopulmonary connection (AP) Fontan was associated with the highest arrhythmia risk compared to extracardiac conduit (ECC), followed by lateral tunnel (LT).
AP and LT Fontan were associated with progressively higher risks of both tachyarrhythmias and bradyarrhythmias compared to ECC Fontan.
Older age at Fontan surgery independently increased the risk of late arrhythmia development.
Late-onset arrhythmias were associated with significantly increased risks of mortality and Fontan failure.
The Korean multicentre Fontan registry included 1492 patients operated between 1979 and 2019, with ECC being the predominant surgical type.
This research examined long-term heart rhythm complications in over 1,400 patients who underwent Fontan surgery — a staged operation performed in children born with a single functioning heart ventricle. The study used data from a large Korean registry spanning 40 years and compared three different surgical techniques: atriopulmonary connection (AP), lateral tunnel (LT), and extracardiac conduit (ECC). After a median follow-up of 14 years, about 1 in 7 patients developed an abnormal heart rhythm, most commonly rapid rhythms (tachyarrhythmias), and this typically occurred in late adolescence. The type of surgery performed had a major impact on arrhythmia risk. Patients who received the older AP technique were nearly 6 times more likely to develop arrhythmias than those who received the newer ECC technique, while LT patients had roughly 3 times the risk. This pattern held for both too-fast and too-slow heart rhythms. Older age at the time of Fontan surgery also modestly but independently increased arrhythmia risk. These findings suggest that the shift in surgical practice toward ECC over the decades has meaningfully reduced long-term rhythm complications. This research also found that developing a late arrhythmia was a warning sign for worse outcomes overall — patients with arrhythmias had significantly higher rates of death and 'Fontan failure' (a state where the Fontan circulation stops working adequately). The Fontan failure rate was 20% and the mortality rate was 9.3% across the entire cohort. These findings highlight the importance of ongoing cardiac monitoring for all Fontan patients, particularly those who received older surgical techniques, and suggest that arrhythmias may be an early indicator that a patient's overall Fontan circulation is deteriorating.
Yoon J, Ahn K, Kim S, Lee C, Kang I, Song J, et al.. (2026). Late arrhythmias following Fontan completion: insights from a Korean Multicentre Fontan Registry of over 1000 extracardiac conduit surgeries.. Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology. https://doi.org/10.1093/europace/euag123