• adult congenital heart disease
• arrhythmia
• catheter ablation
• Fontan
• remote magnetic navigation
• TCPC

Background and aims: The atrio-pulmonary (AP) Fontan and its modern counterpart, the total cavo-pulmonary connection (TCPC), are palliative operations for patients with functionally single-ventricle physiology in which a two-ventricle repair is not possible. Despite the success of the cardiac surgery and modern medicine, post-surgical supraventricular tachycardias (SVTs) remain significant contributors to morbidity and mortality and present considerable management challenges. This study aims to assess the efficacy and safety of catheter ablation, using three-dimensional (3D) image integration and other advanced technologies in patients with a Fontan circulation.
Methods: All patients with a Fontan circulation who underwent ablation for SVTs between February 2008 and November 2024 were enrolled in this study. All electrophysiological and ablation data were collected. Procedures were carried out with electro-anatomical mapping and 3D image integration, either manually or using remote magnetic navigation (RMN). Acute success, procedural complications, and recurrences were assessed.
Results: A total of 71 patients [41 male (58%), 24 with AP Fontan (34%), mean age at first procedure 29 (IQR 23-37) years] with a Fontan circulation were enrolled in the study. One hundred twenty-eight electrophysiological studies (59 in AP Fontan patients) and 125 ablation procedures were performed. RMN was carried out in all TCPC with no trans-baffle puncture. A total of 274 distinct arrhythmia substrates (151, 55% in AP Fontan patients) were identified. The majority of SVTs in AP Fontan were macro re-entrant atrial tachycardia (MRATs) and focal atrial tachycardias (FATs) in the right atrium (46% and 47% respectively). A similar incidence of MRATs (39%, in about half of cases cavotricuspid isthmus-like related) and FATs (37%, in about half of cases from the right atrium) were induced in patients with TCPC. Acute success was achieved in 107 ablation procedures (84%), 81% in the AP Fontan and 86% in the TCPC group (p=NS). There were 4 intra-operative complications. Over a median follow-up duration of 11 (IQR 4-48) months, 37 patients (52%) had recurrences, with a major incidence in AP Fontan (87.5% versus 34%, p<0.001), and in 14 cases a new arrhythmia was observed. At multivariable regression analysis, the risk of arrhythmia recurrence was significant in patients with AP Fontan (HR 3.372, 95% CI 1.451-7.839, p=0.005) with a freedom from recurrences of 35% in AP Fontan and 60% in TCPC at 24 months.
Conclusions: In adult patients after the Fontan procedure, SVTs ablation with a RMN approach is a safe and effective procedure in specialized centres. In patients with multiple procedures, SVTs originated from different atrial sites and/or with different mechanisms, suggesting a progressive atrial disease in this cohort of patients. Despite the rate of recurrences is significant, catheter ablation improves freedom from arrhythmias, especially in patients after TCPC procedure.