Catheter Ablation of Atypical AV Nodal Reentrant Tachycardia
What is the efficacy and safety of conventional slow pathway ablation in atypical atrioventricular nodal reentrant tachycardia (AVNRT)?
Retrospective data were pooled from databases of seven high-volume electrophysiology laboratories. A total of 2,079 patients with AVNRT were subjected to slow pathway ablation. In 113 patients, atypical AVNRT or co-existent atypical and typical AVNRT without other concomitant arrhythmia was diagnosed. Ablation data and outcomes were compared with a group of age- and sex-matched control patients with typical AVNRT.
Fluoroscopy and radiofrequency current delivery times were not different in the atypical and typical groups (20.3 ± 12.2 vs. 20.8 ± 12.9 min, p = 0.730 and 5.9 ± 5.0 vs. 5.5 ± 4.5 min, p = 0.650), respectively. Slow pathway ablation was accomplished from the right septum in 110 patients, and from the left septum in three patients, in the atypical group. There was no need for additional ablation lesions at other anatomical sites, and no cases of AV block were encountered. Recurrence rates of the arrhythmia were 5.6% in the atypical (6/108 patients), and 1.8% in the typical (2/111 patients) groups, in the next 3 months following ablation (p = 0.167).
The authors concluded that the conventional ablation at the anatomical area of the slow pathway is the therapy of choice for both typical and atypical AVNRT.
The present study represents the largest series of patients with atypical AVNRT, who comprise about 6% of all patients with AVNRT, and confirms prior and smaller reports, that the same slow pathway participates in both AVNRT varieties. Importantly, mapping and ablation attempts at the coronary sinus os or higher in the septal area were not necessary for the elimination of the arrhythmia. The study suggests that the slow pathway ablation is equally safe and effective in both types of AVNRT, although the relatively small number of patients and short follow-up may have resulted in an overestimate of the ablation efficacy.
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