Focal pulsed field ablation in complex cases of atrial tachycardia - feasibility, outcome and safety of a novel technology
Authors: Bahlke F , Englert F , Popa M , Krafft H , Tunsch Martinez A , Syvaeri J , Tydecks M , Telishevska M , Lennerz C , Abdiu E , Lengauer S , Hessling G , Deisenhofer I , Erhard N 
Published: May 2024

Abstract

Introduction
The importance of pulsed-field ablation (PFA) is rising in the field of catheter ablation. Nevertheless, the use of a single-shot devices is limited to pulmonary vein isolation (PVI). Thus, significance of technologies implementing point-by-point PFA is growing. A commercially available system uses radiofrequency (RF) catheters in combination with a PFA-generator. Data on the use is sparse, especially for treating atrial tachycardia (AT). The aim of this study was to evaluate feasibility, safety and mid-term outcomes of point-by-point PFA in complex cases of AT.

Methods
All consecutive patients treated with a focal PFA-catheter (N = 34) suffering from AT were included. A high density map was created in all patients. Established RF catheters were employed as PFA catheters with the PFA generator. Except for the ablation generator, the standard setting at our clinic for ablation of AT was not changed. In case of sinus rhythm at the beginning, burst stimulation was performed in order to induce the clinical AT. Acute procedure success was defined as creation of ablation lesions preventing the mechanism of the clinical tachycardia and/or non-inducibility of the clinical AT. Outcome and safety was evaluated during the hospital stay and visits at our outpatient clinic, including 7d-Holter-ECG.

Results
In all 34 included patients, acute procedure success was achieved. Baseline characteristics are listed in table 1. In average, patients had 1,21 ± 0,88 ablations before, 67,6% of patients had linear lesions in the past. Mean procedure duration was 102,7 ± 30,3 min, the LA dwell time was 75,0 ± 24,7 min (table 2).
Any desired lesion set was accomplished (pulmonary vein isolation, linear lesions or ablation of focal AT/localized reentry) with the focal PFA technology. Linear lesions were ablated in 32 (94,1%) patients, while a pulmonary vein isolation was performed in 12 patients (35,3%). Ablation of localized reentries was necessary in two patients (5,9%). In total, 51 linear lesions were created: 27 anterior lines, 18 roof lines, 5 CTI-lines and one posterior box; bidirectional block was proven in all cases. Furthermore, three patients suffered a macro-reentry due to reconnected pulmonary veins. The site of termination of the tachycardia is shown in Figure 1.
No procedure-related minor or major complications occurred (no groin complications, no stroke, no pericardial tamponade). After a mean follow-up of 179,4 ± 107,8 days, 8 patients (23,5%) suffered a recurrence of any atrial arrhythmia.

Conclusion
Applying focal PFA with well-known radiofrequency ablation catheters is safe and efficient, also in cases of atrial tachycardia. The integration of the new system into clinical practice is feasible and did not prolong the procedures. Acute procedure success was achieved in all cases. For further evaluation of efficacy and safety, a control group of patients treated with radiofrequency or a randomized trial is needed.