Ablation of Atrial Arrhythmias After the Atriopulmonary Fontan Procedure: Mechanisms of Arrhythmia and Outcomes.

OBJECTIVES: This study sought to describe atrial arrhythmia mechanisms, acute outcomes, and long-term arrhythmia burdens following catheter ablation in adult atriopulmonary (AP) Fontan patients.

BACKGROUND: Atrial arrhythmias are a significant cause of morbidity and mortality in the AP Fontan population.

METHODS: Sixty consecutive atrial arrhythmia ablations were reviewed in 42 AP Fontan patients (31 ± 8 years of age), performed between 1998 and 2017. The number of induced and ablated tachycardias was recorded for each case, as well as the ability to ablate the suspected clinical tachycardia. Longer-term arrhythmia burden was assessed by using a 12-point clinical arrhythmia severity score.

RESULTS: Intra-atrial re-entrant tachycardia (IART) was induced in 93% of cases (n = 56), atrioventricular re-entrant tachycardia in 2 (3%) and atrioventricular nodal re-entrant tachycardia in a single case. The mean number of tachycardias induced per case was 2.3. The critical isthmus for IART was mapped to the lateral (n = 10), inferolateral (n = 8), posterior/posterolateral (n = 16), or septal (n = 10) systemic venous atrium, or to the pulmonary venous atrium (n = 4). Ablation of all inducible tachycardias was achieved in 62%, ablation of at least one (but not all) inducible tachycardias in 25%, with failure to ablate any tachycardias in 13%. The suspected clinical arrhythmia was ablated in 50 cases (83%). Catheter ablation resulted in a significant reduction in arrhythmia score at 3 to 6, 12, and 24 months, irrespective of whether all inducible tachycardias were ablated, or the suspected clinical arrhythmia only. Twelve patients (29%) underwent at least one repeat ablation procedure, with a mean time between ablations of 2.7 ± 3.0 years. There were no cases of periprocedural death, stroke or cardiac tamponade.

CONCLUSIONS: Catheter ablation can be a safe and effective intervention that will significantly reduce arrhythmia burden in the AP Fontan patient.