Sequential Hybrid PFA and RF Ablation of the Anterior Mitral Line to Improve Lesion Durability

Background:
Pulsed field ablation (PFA) is a non-thermal ablation technique based on irreversible electroporation and has become an established method for pulmonary vein isolation (PVI). Focal PFA is increasingly used in more complex arrhythmia cases, where targeted ablations beyond the pulmonary veins are required. For anterior mitral line (AML) ablation in particular, focal PFA has shown high acute success rates, but reconnections, especially near the base of the left atrial appendage, remain a frequent issue, due to increased myocardial thickness. To address this, we adopted a hybrid approach using focal PFA followed directly by point-by-point radiofrequency ablation (RFA) at the same sites, aiming to improve lesion durability.

Methods:
In this retrospective single-center analysis, 14 patients underwent left atrial ablation including AML ablation using a sequential hybrid technique. High-density mapping was performed followed by complete PVI. Focal PFA was applied point-by-point along the AML using the TactiCath™ Quartz catheter (Abbott Laboratories, Chicago, IL, USA) connected to the CENTAURI™ generator (CardioFocus, Marlborough, MA, USA) with 25 A R-synchronized pulse trains (10 pulses per lesion, 5 mm spacing). Following PFA, the same catheter was reconnected to an RF generator to perform LSI-guided thermal ablation (target LSI ≥5.0) at the same sites along the AML. Follow-up included scheduled Holter monitoring at 3, 6, and 12 months.

Results:
The cohort included 14 patients (mean age 69.6 ± 8.6 years), of whom 2 (14.3%) had paroxysmal atrial fibrillation (AF), 3 (21.4%) persistent AF, and 9 (64.3%) perimitral atrial flutter. In 13 cases (92.9%), the procedure was a redo ablation, with an average of 1.8 ± 1.0 prior left atrial procedures. The mean low-voltage area in the left atrium was 59 ± 17.5%. All patients received an anterior mitral line using focal PFA followed by RFA. On average, 20.6 ± 2.4 PFA tags and 20.4 ± 2.6 RFA tags were applied, with a total RF application time of 522.9 ± 64.1 seconds. Pulmonary vein re-isolation was performed in 8 patients (57.1%), and additional linear lesions (roof line and/or posterior box) were placed in 12 patients (85.7%). Mean procedure duration was 117.9 ± 33.3 minutes, with a fluoroscopy time of 9 ± 4.1 minutes. Acute procedural success, defined as complete electrical isolation of all pulmonary veins and bidirectional block across all ablation lines, was achieved in all patients. During a mean follow-up of 336.3 ± 85.2 days, no recurrence of atypical atrial flutter was observed. No serious adverse events occurred within 30 days post-procedure.

Conclusion:
To our knowledge, this is the first report of a sequential hybrid approach applying focal PFA and RFA along the same anterior mitral line within a single procedure. In contrast to previously described dual-energy protocols targeting different regions, both energies were applied at the same site to improve lesion durability. This sequential use of both modalities may help overcome limitations of each technique when used in isolation, particularly in anatomically challenging regions like the AML. In this small cohort, the approach resulted in complete procedural success without recurrence of atypical flutter or procedure-related complications during follow-up. While limited by its retrospective design and lack of a control group, the findings support further prospective evaluation.