Late arrhythmias following Fontan completion: insights from a Korean Multicentre Fontan Registry of over 1000 extracardiac conduit surgeries

Awareness of long-term arrhythmia complications after Fontan surgery is increasing, but the impact of surgical type and risk factors on arrhythmia development remain incompletely understood.

We retrospectively analysed 1492 Fontan patients from the Korean multicentre registry (1979–2019), categorized into atriopulmonary connection (AP) (n = 106), lateral tunnel (LT) (n = 234), and extracardiac conduit (ECC) (n = 1143) with a median follow-up of 14 years. Arrhythmias occurred in 13.3% of patients at a median age of 17.3 years (tachyarrhythmias 9.9%, bradyarrhythmias 6.8%). At 20 years, freedom from any arrhythmia, tachyarrhythmia, and bradyarrhythmia was 82.5%, 86.9%, and 90.5%, respectively. On multivariable analysis, AP (HR 5.89, 95% CI 3.75–9.25; P < 0.001) and LT (HR 2.85, 95% CI 1.93–4.21; P < 0.001) were associated with a higher risk of arrhythmia compared with ECC. Older age at Fontan surgery also independently increased arrhythmia risk (HR 1.06, 95% CI 1.03–1.10; P < 0.001). Compared with ECC Fontan, LT Fontan and AP Fontan were associated with a progressively higher risk of both tachyarrhythmias (HR 2.99 and 8.20, respectively) and bradyarrhythmias (HR 2.63 and 5.47, respectively; all P < 0.001). The all-cause mortality rate and Fontan failure rate were 9.3% (0.69 per 100 patient-years) and 20.0% (1.61 per 100 patient-years), respectively. Late-onset arrhythmias were associated with an increased risk of mortality and Fontan failure (P = 0.003 and P < 0.001).

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.