Left Atrial Substrate Modification for Long-Standing Persistent Atrial Fibrillation and Left Atrial Macro- or Micro-Reentrant Tachycardia Using a Single-Shot Pulsed Field Ablation System—A Case Series

<b>Background:</b> Pulsed field ablation [PFA] is a novel ablation technique for pulmonary vein isolation [PVI] in patients with paroxysmal and persistent atrial fibrillation. However, data for the efficacy and safety of PFA for left atrial substrate modification using a single shot PFA system, in patients with long-standing persistent atrial fibrillation [AF] and left atrial macro- as well as micro-reentrant atrial tachycardia [LAMRT], are scarce. Here, we provide a small, single-center case series regarding the efficacy and safety of left atrial substrate modification using a single-shot PFA system. <b>Methods:</b> Nine patients with long-standing persistent AF and LAMRT underwent redo-PVI and left atrial substrate modification using a single-shot PFA system. Patients were subsequently followed up for 1 year. <b>Results:</b> The median age was 64 years [IQR 55.5-75], with 44% of the participants being female. The median time since the first diagnosis of AF was 7 years [IQR 4-15.5]. After re-PVI, posterior wall isolation was performed in five patients, roof isolation in six patients, and anterior wall ablation between the superior mitral annulus and the right superior pulmonary vein [RSPV] in five patients. In two patients, cavotricuspid isthmus ablation was additionally performed to treat typical atrial flutter. The acute procedural success rate was 100%, with all LAMRTs and typical flutters successfully terminating by ablation. At 1-year follow-up, four patients [44%] experienced a recurrence of any atrial arrhythmia. Median time to recurrence was 164 days [138-212.8]. Importantly, no acute or chronic complications were observed. <b>Conclusions:</b> In this small, single-center case series, left atrial substrate modification for long-standing persistent AF and AT using a single-shot PFA system was safe and showed an excellent acute success rate.