Contemporary catheter ablation of complex atrial tachycardias after prior atrial fibrillation ablation: pulsed field versus radiofrequency current energy ablation guided by high-density mapping.

BACKGROUND:Catheter-ablation (CA) of post-ablation left-atrial tachycardias (LAT) can be challenging. So far, pulsed-field ablation (PFA) has not been compared to standard point-by-point radiofrequency-current (RFC) energy for LAT ablation. AIMS:To compare efficacy of PFA versus RFC in patients undergoing CA for LAT. METHODS:Consecutive patients undergoing LAT-CA were prospectively enrolled (09/2021-02/2023). After electro-anatomical high-density mapping, ablation with either a pentaspline PFA-catheter or RFC was performed. Patients were matched 1:1. Ablation was performed at the assumed critical isthmus site with additional ablation, if necessary. Right-atrial-tachycardia (RAT) were ablated with RFC. Acute and chronic success were assessed. RESULTS:Fifty-six patients (n=28 each group, age 70 ± 9 years,75% male) were enrolled.A total of 77 AT (n=67 LAT, n=10 RAT; 77% macroreentries) occurred with n=32 LAT in the PFA- and n=35 LAT in the RFC-group. Of all LAT, 94% (PFA-group) vs. 91% (RFC-group) successfully terminated to sinus rhythm or another AT during ablation (p=1.0). Procedure times were shorter (PFA: 121 ± 41 vs. RFC: 190 ± 44 mins, p<0.0001) and fluoroscopy times longer in the PFA-group (PFA: 15 ± 9 vs. RFC: 11 ± 6mins, p=0.04). There were no major complications. After one-year follow-up, estimated arrhythmia-free survival was 63% (PFA-group) and 87% (RFC-group), (Hazard-Ratio 2.91 (95-%-CI: 1.11-7.65), p=0.0473). CONCLUSION:PFA of post-ablation LAT using a pentaspline catheter is feasible, safe and faster but less effective compared to standard RFC ablation after one-year of follow-up. Future catheter-designs and optimization of the electrical field may further improve practicability and efficacy of PFA for LAT.