Cryoablation of atrioventricular nodal reentry tachycardia with utilization of three-dimensional electroanatomic mapping system
Authors: Podlogar V , Prolic Kalinsek T , Topalovic M , Stublar J , Kuhelj D , Lakic N , Jan M 
Published: May 2023

Abstract

Funding Acknowledgements
Type of funding sources: None.

Introduction
Catheter ablation for atrioventricular nodal reentry tachycardia (AVNRT) is usually performed with radiofrequency (RF) energy, which carries a risk of collateral conduction system injury. Cryoablation is a safer, but less effective alternative. Utilization of the three-dimensional electroanatomic mapping (3D EAM) system can potentially overcome some limitations of cryoablation and possibly improve procedural outcome.

Purpose
We retrospectively analyzed the feasibility, efficacy, and safety of cryoablation of AVNRT guided by 3D EAM system.

Methods
In this retrospective study, we analyzed consecutive patients who underwent cryoablation of AVNRT in our institution from April 2017 to May 2022. All procedures were performed with either magnetic-based or impedance-based system. A 3D model of the right atrium was created and important structures were annotated. Cryomapping was performed at the presumed slow pathway location, followed with cryoablation when appropriate. Location of cryoablation was annotated either with a dot superimposed from the distal electrode of the cryoablation catheter to the surface of the 3D model or the position of the cryoablation catheter was snapshotted. Intracardiac echocardiography (ICE) was utilized at the operator’s discretion. Procedural endpoint was AVNRT noninducibility, with up to one atrial echo beat allowed. Follow-up was performed with a visit to an outpatient clinic or with a telephone interview.

Results
The study included 122 consecutive patients (49/122 male; 33/122 pediatric patients, mean age 40.4 ± 22.1 years; mean BMI 25.0 ± 5.7 kg/m2). Altogether, 128 procedures were performed and 124 slow-fast AVNRT were diagnosed, 4 patients had slow-slow AVNRT. In six patients the procedure was repeated due to the recurrence of AVNRT. In two procedures, cryoablation was performed in the left atrium. Impedance-based 3D EAM system was used in 89.8% (115/128) of cases, while magnetic-based 3D EAM system was used in 10.2% (13/128) of cases. In 21.9% (28/128) of cases ICE was utilized. Median number of cryoablations was 3 (2 – 4) and median ablation time was 720 s (480 – 960 s). Cryomapping during ongoing AVNRT was possible in 52.3% (67/128) of cases, with mean time to termination of 13.4 ± 6.5 s. Mean procedural time was 80.9 ± 39.3 minutes. There were no major complications related to the procedure. Endpoint was achieved in 100% (128/128) of cases. Follow-up was completed in 96.7% (118/122) of cases, mean follow-up time was 484.7 ± 342.0 days. Arrythmia-free survival rate after first procedure was 88.1% (104/118). When all repeated procedures were included, the arrhythmia-free survival rate was 94.9% (112/118).

Conclusion
Cryoablation of AVNRT with utilization of the 3D EAM system is feasible, effective, and safe. Although, the success rate after first procedure is lower than expected, the procedure can be safely repeated to improve the outcome.