Atrioventricular nodal reentrant tachycardia ablated from left atrial septum: clinical and electrophysiological characteristics and long-term follow-up results as compared to conventional right-sided ablation.

Radiofrequency catheter ablation or modification of the slow pathway is almost always performed on the right atrial side of the interatrial septum, however, this is not possible in rare cases. We evaluated the clinical and electrophysiological characteristics and long-term follow-up results of patients whose AVNRT could only be ablated from the left posterior atrial septum after repeated unsuccessful attempts on the right atrial side and to observe if they differ from those undergoing ablation with the conventional right-sided approach. Of 587 cases with symptomatic typical AVNRT, 9 patients (1.5%) in whom RF energy delivered to the right atrial septum with the integrated approach failed to ablate or modify the slow pathway were enrolled in the study group (group 1) while the others served as controls (group 2). There was no significant difference between the groups regarding clinical characteristics, dual AV nodal physiology, sinus cycle lengths, AH and HV intervals, procedural complication rates, or recurrence rates in the mean follow-up duration of 34 +/- 11 months. Only tachycardia cycle length (TCL) was significantly higher in group 1 than in group 2, which was mainly due to the difference in AH intervals (P < 0.001 for both). Slow pathway ablation was performed at the posteroseptal aspect of the mitral annulus in 6 and the midseptal aspect in 2 cases. In 1 case, attempts at ablation on the left atrial septum also failed. When the conventional right-sided approach fails to ablate or modify the slow pathway conduction, left-sided ablation can safely and effectively be employed, with success rates and long-term follow-up results comparable to the conventional right-sided approach.