Feasibility of electroanatomical mapping guided slow pathway modification using only an ablation catheter for the treatment of atrioventricular nodal reentry tachycardia

Fluoroscopy guided slow pathway (SP) catheter ablation is the cornerstone of invasive treatment of atrioventricular nodal reentry tachycardia (AVNRT) in adult patients. The procedure is associated with a 1-2% risk of atrioventricular (AV) block due to the close proximity of the SP to the conduction system. Electroanatomical mapping (EAM) guided SP ablation may enhance the safety of the procedure by directly demonstrating the His area and its proximity to the ablation target. The optimal mapping method for the identification of the SP by EAM has not been established. A limited number of methods have been published in the literature, with the majority of them using multipolar catheters for high-density mapping of the septal area.

In the presented study, we aimed to assess the feasibility of performing EAM guided SP ablation in patients with documented AVNRT using only an ablation catheter. The ablation target was defined as a combination three criteria (anatomical site, timing of activation and electrogram (egm) characteristics). The omission of use of multipolar catheter limits the cost of the procedure and therefore improves the widespread implementation of the technique.

This is a prospective single-center study that included patients with AVNRT, confirmed by electrophysiological maneuvers. Fast anatomical mapping (FAM) and activation mapping (LAT) in sinus rhythm was performed in the right septal area using a three-dimensional mapping system (CARTO-3, Biosense Webster Inc., Irvine, CA) and an irrigated ablation catheter (THERMOCOOL SMARTTOUCH SF, Biosense Webster, Inc., Irvine, California). The His area was marked in the created maps (His cloud). LAT maps were created with automatic annotation at the maximum negative downslope. Maps were divided in isochronal zones of 8 steps. Ablations targets were defined as the areas that fulfilled all three criteria: location in the latest activation zone, adjacent to a zone of isochronal crowding, egm showing an a to v ratio of at least 1:3. Non-inducibility of the tachycardia was the endpoint of the study.

36 patients were enrolled in the study. SP ablation guided by EAM was successful in 34 patients (94.4% success rate). No complications were reported in the cohort. The mean age of the patients was 50±13-year-old. The mean number of points of the created LAT maps was 115.4±34.75 and the mean mapping time was 6.31± 1.41 minutes. The mean distance between the targeted area and the His egm was 20.36 ± 5.18 mm with a time difference of 40.36± 13.56ms. Mean ablation time was 1.96 ± 0.67 min. Fluoroscopy time was 2.76 ± 1.17minutes.

SP ablation guided by EAM may be a valuable alternative ablation strategy for the treatment of patients with AVNRT. The technique is feasible by using an ablation catheter for both mapping and ablation purposes.