Pulmonary Vein Isolation with a Novel Size-Adjustable Cryo-Balloon Catheter: A Tailored Ablation Protocol.

Background: Pulmonary vein isolation (PVI) is a common therapeutic approach for symptomatic atrial fibrillation (AF). Among various techniques, cryo-balloon (CB) PVI is widely adopted, but, to date, established CB systems have had fixed balloon sizes. A novel size-adjustable CB, allowing balloon size adjustments during ablation, lacks sufficient data on optimal utilization in patient care. This study aims to systematically investigate this feature with a tailored ablation protocol. Methods: Our single-center prospective study included patients with paroxysmal or persistent atrial fibrillation undergoing first-time PVI with the size-adjustable CB from July 2023 to February 2024. Ablation was performed using the balloon size that provided better occlusion. The ablation protocol involved an initial occlusion test with the small balloon size (28 mm). If optimal occlusion (occlusion level 4) could not be achieved, an attempt with the larger balloon (31 mm) was initiated. Ablation was conducted using the balloon configuration that provided better occlusion of the pulmonary vein ostium. Results: Our prospective study includes 50 patients (median age [interquartile range, IQR]: 72 [65; 79] years, 24 [48.0%] females, and 35 [70.0%] patients with paroxysmal AF). The median procedure duration (IQR) was 77 (65; 96) minutes, and the median fluoroscopy time (IQR) was 17.7 (12.5; 22.0) min. PVI was successfully accomplished in each treated pulmonary vein (PV), with 87.4% of PVs isolated during the first freeze. The large balloon configuration was used to isolate 16.8% of PVs. Conclusions: The utilization of the size-adjustable CB, combined with the presented tailored ablation workflow, appears to facilitate effective and efficient pulmonary vein isolation. The use of a larger balloon configuration appears beneficial in isolating a significant proportion of the PVs.