Catheter Ablation of Multiple Unstable Macroreentrant Tachycardia Within the Right Atrium Free Wall in Patients Without Previous Cardiac Surgery

BACKGROUND: Macroreentrant atrial tachycardia (AT) involving the right atrial free wall (RAFW) has been reported in patients without atriotomy. Catheter ablation of these ATs remains challenging due to the multiple morphologies of ATs with unstable reentrant circuits in some patients. The purpose of this study was to clarify the electrophysiological characteristics of these ATs and attempt the novel approach for catheter ablation. METHODS AND RESULTS: Electrophysiological study and catheter ablation were performed in 17 patients (14 men; 71 quartile 1, 67; quartile 3, 76 years) with reentrant ATs originating from the RAFW using 3D mapping. All patients had no history of cardiac surgery. Clinical ATs with stable cycle length and atrial activation were identified in 11 patients (group A). All ATs were successfully ablated. In the remaining 6 patients, clinical tachycardia continuously changed, with a different cycle length and P-wave morphology and atrial activation sequence during mapping or entrainment study (group B). A complete isolation of the RAFW was attempted in group B. After complete isolation was achieved in 5 of 6 patients, ATs were not induced in these 6 patients. The number of previous failed catheter ablations and induced ATs were higher in group B than in group A. During 31 (19; 37) months of follow-up, AT recurrence developed in 27% patients from group A and 33% from group B. CONCLUSIONS: Multiple and unstable macroreentrant ATs from the RAFW can occur in patients without a history of cardiac surgery. The RAFW isolation has the potential to abolish all ATs.