Slow/Fast Atrioventricular Nodal Reentrant Tachycardia Catheter Ablation Guided by Atrial Resetting: The New Insight.

Abstract

Background: Atrial resetting can be used for discerning the anterograde pathway in slow/fast atrioventricular nodal reentrant tachycardia (AVNRT).

Objectives: Assess the prevalence of right inferior extension (RIE) and left extension (LE) and the potential impact on the ablation approach.

Methods: During the electrophysiological study of patients with slow/fast AVNRT, a decremental supraventricular extrastimulus was delivered within the vulnerability window of the tachycardia cycle at two distinct sites: the infero-paraseptal area of the Koch triangle (near the RIE) and the proximal few centimeters of the coronary sinus (near the LE). The site with the latest extrastimulus (longest H-Stim) that could reset the tachycardia was defined as the site of the anterograde slow pathway.

Results: Thirty-six patients were enrolled over a 1-year period. Resetting couldn't be performed in 10 patients (28%) due to non-sustained tachycardia and one patient due to failed atrial capture. Among the remaining 25 patients (69%), 18 (72%) had the best resetting from the RIE, 5 (20%) from the LE, and 2 (8%) had two alternating AVNRT. The mean H-Stim value in the RIE position was longer when resetting favored RIE compared to LE (46±13 vs 16±21ms; p<0.001); a similar pattern was observed in the LE position (59±20 vs 15±18ms; p<0.001). Ablation of the left inferior extension could be performed from the right side but significantly closer to the His bundle compared to the RIE (9.6±3 vs. 18.5±4mm, p<0.001).

Conclusion: Left extension AVNRT is a common finding and can be ablated by a right-sided approach in most cases.