Background: After the surgical correction of tetralogy of Fallot, surgical scars and natural obstacles form pathways capable of supporting an atrial tachyarrhythmia (AT). Radiofrequency (RF) ablation is effective, although the few studies published on this topic had relatively short follow-up periods.

Aim: The aims of the study were to evaluate the acute and long-term effects of RF ablation of AT and examine the charac­teristics of arrhythmia recurrence.

Methods: Tetralogy of Fallot patients (n = 16, age 44.7 ± 10.7 years) referred for ablation of ATs, appearing 25.7 ± 9.6 years after repair, were studied.

Results: Twenty-five ATs were ablated, including 16 cavo-tricuspid isthmus atrial flutters (CTI-AFLs) and nine intraatrial reentrant tachycardia (IART). In one patient with paroxysmal atrial fibrillation (PAF), pulmonary vein isolation was also performed. Ten patients had permanent, and six had paroxysmal arrhythmia prior to the first ablation. Four patients had PAF. Regardless of the type of first ablated arrhythmia, all 16 patients required CTI-AFL ablation. The effectiveness of the first RF ablation reached 88%. The acute efficacy of RF ablation was 100% for CTI-AFL and 78% for IART. Long-term follow-up was possible in 15 out of 16 patients (mean follow-up 68.8 ± 36.6 months). Four patients were free of sustained arrhythmia, nine (60%) had AF. After the last RF ablation, an episode suggestive of CTI-AFL/IART was documented only in one patient.

Conclusions: Ablation of CTI-AFL/IART in tetralogy of Fallot patients is safe and effective. AF was observed in most patients during the long-term follow-up. Regardless of the type of the first ablated arrhythmia, all patients required CTI-AFL ablation.