PO-04-157 PREVALENCE AND PREDICTABLE FACTORS OF LATE ARRHYTHMIAS AFTER THE FONTAN COMPLETION

Abstract

Many patients with highly complex congenital heart disease could survive thanks to the Fontan operation. However, there is growing awareness of its long-term complications, including arrhythmias. This study aims to demonstrate the prevalence of late arrhythmia and identify predictors of developing arrhythmias in Fontan patients with long-term follow-up. We conducted a Retrospective analysis of patients with Fontan surgery between 1979 and 2019 using the Korean multi-center Fontan registry (N=1673). Arrhythmias were presented in 201 patients with a median age of 19.8 years, who were 42% of total atriopulmonary (AP) Fontan, 24% of total lateral tunnel (LT) Fontan, and 6% of total extracardiac conduit (ECC) Fontan. The median follow-up duration since Fontan surgery was 13.6 years. Tachyarrhythmia was developed in 141 patients. The most common tachyarrhythmia was intra-reentrant atrial tachycardia in 70 patients, followed by re-entrant supraventricular tachycardia in 35 patients. Direct cardioversion was performed in 40 patients(28%), and catheter ablation was performed in 22 patients (16%). Twenty-two patients(16%) and 48 (34%) underwent arrhythmia surgery and Fontan conversion each. Bradyarrhythmia occurred in 88 patients, sinus node dysfunction in 54 patients, and high degree atrioventricular block in 34 patients. Most patients required permanent pacemakers. Twenty year-freedom survival from any arrhythmia, tachyarrhythmia and bradyarrhythmia was 81.9% (95% CI, 79.1-84.8), 88% (95% CI, 85.6-90.4), and 91.9% (95% CI, 90.1-93.9), respectively. On multivariable analyses, age at Fontan surgery and left isomerism were significant predictive factors of developing an arrhythmia (HR 1.07 [1.04-1.09], P<0.001, HR 1.81 [1.15-2.82], P=0.01). The patients with ECC Fontan were less likely to develop arrhythmia than AP or LT Fontan. (HR 0.48 [0.35-0.65], P<0.001). The older age at Fontan surgery and non-ECC Fontan patients were highly susceptible to developing tachyarrhythmia( HR 1.1 [1.05-1.20], P<0.001, HR 3.0 [2.01-4.49], P<0.001). For bradyarrhythmia, left isomerism and the longer time after Fontan surgery was identified significant risk factor of developing bradyarrhythmia. (HR 2.29 [1.24-4.25], P=0.008, HR 1.39 [1.01-1.07], P=0.02). Arrhythmia is a significant burden and inevitable complication in Fontan patients during long-term follow-up, especially those who underwent Fontan surgery in old age and non-ECC Fontan patients for tachyarrhythmia.