Aim: Post-operative atrial tachyarrhythmias (AT) in patients with tetralogy of Fallot (ToF) are associated with congestive heart failure, stroke, and cardiac death. Effective treatment is therefore essential. The aim of the study is to evaluate long-term outcome of ablative therapy of AT in ToF patients and to study characteristics of AT recurrences.
Methods and results: Tetralogy of Fallot patients (N = 38, age 43 ± 12 years) referred for ablation of post-operative AT, appearing 26 ± 10 years after complete repair, were studied. Electro-anatomical/entrainment mapping was performed prior to ablation. Successful ablation was defined as (i) achievement of bi-directional conduction block for isthmus-dependent atrial flutter (IDAF), (ii) termination during ablation for intra-atrial reentrant tachycardia (IART) and focal atrial tachycardia (FAT). Fifty-two AT were ablated, including 37 IDAF [cycle length (CL) 294 ± 70 ms], 11 IART (CL 295 ± 46 ms), and 4 FAT (CL 371 ± 93 ms). Ablation was successful in 98%. Fifty-one of 52 AT involved the cavo-tricuspid isthmus and/or the area between scar tissue related to prior atriotomy incisions and the inferior caval vein. Multiple AT developed in 11 patients, with different mechanisms in 9. After 45 ± 24 months, 32 patients were in sinus rhythm; 5 used anti-arrhythmic drugs.
Conclusion: Ablative therapy of AT in ToF patients is an effective curative treatment modality with a high procedural success rate. Sinus rhythm during long-term follow-up was obtained in the majority of patients. Fifty-one of 52 AT originated from sites related to surgical incisions created at complete repair, suggesting that extending the atriotomy incision towards the inferior caval vein during cardiac surgery combined with surgical ablation of the cavo-tricuspid isthmus will be effective in preventing development of AT.