Left atrial size impacts efficacy of pulsed field ablation with the variable-loop circular catheter: insights from the VARI-RUHR multicenter real-world registry

Abstract Background Pulsed field ablation (PFA) ablation with the novel variable-loop circular catheter (VLCC) allows real-time, three-dimensional visualization of the catheter position, tissue contact and lesion delivery while performing atrial fibrillation (AF) ablation. Purpose The VARI-RUHR registry aims to provide real-world insights into procedural characteristics, outcomes and safety of PFA using the VLCC. Methods Consecutive patients with symptomatic atrial fibrillation undergoing pulmonary vein isolation (PVI) using the VLCC with integration of three-dimensional mapping were enrolled. The primary efficacy endpoint was the acute ablation success rate defined as successful electrical isolation of all targeted pulmonary veins (PVs) during the index procedure. The primary safety end point was the occurrence of a severe adverse event within 7 days of ablation. Results At two centers, 101 patients (67.9 ± 10.1 years of age; 55.4 % male; 42.6 % paroxysmal AF) underwent PFA, including 4 re-do ablations. Mapping and ablation were performed exclusively with the VLCC. Mean total procedure and fluoroscopy times were 77.5 ± 18.9 min. and 10.1 ± 6.1 min. respectively. As operator experience increased, fluoroscopy time decreased significantly (11.4 ± 6.9 vs. 8.5 ± 4.5 min; p=0.017), while the necessity of supplementary applications following remapping became increasingly apparent (61.4 vs. 25.7%; p=0.001). First pass isolation was achieved in 71.5% of treated PVs (16.6 ± 1.9 applications/patient) and was less common in patients with persistent AF (30 vs. 49% first pass isolation rate per patient; p=0.072). Acute reconnections occurred predominantly in patients with mild-to-moderate LA enlargement (83.9% of patients in the second tertile of LA-diameter, p=0.007, Cramer’s V=0.33), primarily in the left superior PV (51.0% of LSPVs, p=0.021, Cramer’s V=0.29). Acute procedural success was recorded in 98.0% of patients. There were two vascular access-related, primary serious adverse events. Conclusion In this real-world PFA registry, PFA using the variable-loop circular catheter provided a feasible, safe and efficient approach for PVI in patients with AF. However, first-pass isolation rates were modest, especially in patients with persistent AF and with mild-to-moderate LA enlargement.