Catheter ablation of atypical left atrial flutter - Comparison of outcomes between pulsed field ablation and radiofrequency ablation

Abstract Background Outcomes after catheter ablation of left atrial flutter (LAF) are still suboptimal. Challenges include limitations in both mapping and ablation technologies. Pulsed field ablation (PFA) compared to radiofrequency ablation (RFA) results in larger and more homogeneous ablation lesions. The use of PFA may influence operators to modify their treatment strategies during LAF ablation and affect outcomes. Purpose To compare procedural and outcome characteristics of LAF ablation using either PFA or RFA. Methods We included patients undergoing LAF ablation between Jan 2021 and Jun 2023 at our institution. Baseline and procedural data, including lesion sets, were collected, and patients were followed with 7-day Holter ECG at 3, 6, and 12 months. The primary endpoint was recurrence of any atrial arrhythmia lasting longer than 30 seconds. Results 147 patients were analyzed (median age 71 years, IQR 65-75 years, 65% male). The aetiology of the LAF was deNovo LAF in 22%, LAF after PVI alone in 37% and LAF after PVI plus linear lesions in 42%. The ablation was performed with PFA in 50% and with RFA in 50%. Patients undergoing PFA had fewer prior left atrial ablation procedures (median 1 vs. 1, p=.025). Diabetes was more prevalent in the PFA group (23% vs. 8%, p=.013), other baseline characteristics were similar among the groups. In the PFA group, posterior wall isolation was performed more frequently (81% vs. 15%, p<0.001) and focal substrate modification was performed more frequently in the RFA group (32% vs. 11%, p<0.002). Additional RFA was used in 34 (47%) cases of the PFA group to complete linear lesions, resulting in similar procedure times in both groups (165 min and 167 min). Freedom from arrhythmia at 12 months was similar after RFA and PFA, (66%, CI 55-79% vs. 44%, CI 33-59%, p=0.067). Conclusion When using PFA for LAF instead of RFA, the posterior wall is more frequently targeted for ablation, but the outcomes are similarly suboptimal.