Background: Pulmonary vein isolation (PVI) is an effective treatment for symptomatic atrial fibrillation (AF). 3D-Mapping-System guided radiofrequency (RF) based point-by-point ablation results in favorable clinical outcome, although its complexity demands a long learning curve and multiple procedures are oftentimes required to achieve durable PVI. Balloon-based ablation systems, applying either cryothermal or laser energy, have been developed to possibly solve these limitations, reduce procedure time and increase safety and efficacy of PVI. Visually guided laser balloon (VGLB) ablation by the Cardiofocus© HeartLight system allows for precise PVI under direct endoscopic control and has shown clinical efficacy comparable to 3D-Mapping guided RF ablation. Recently, the next generation of this system (Excalibur^TM) was introduced. This system provides a more compliant balloon to possibly improve visibility during PVI. Procedural data of this promising system are sparse. We sought to determine the safety, efficacy, and learning curve effects of the Excalibur^TM VGLB for the treatment of AF.

Methods: Since April 2018 45 patients (n=5, 11% paroxysmal AF, median age: 68 (Q1: 61, Q3:76) years) underwent PVI using the Excalibur^TM by two operators. The operators were experienced in RF-based and cryothermal procedures, but have not performed any VGLB ablations before. Laser energy was titrated from 5.5-12W. After ablation of a circular lesion a 15-20mm spiral mapping catheter was placed inside the target PV to verify PVI.

Results: A total of 182 PVs were identified and 179/182 PVs (98%) were successfully isolated utilizing the Excalibur^TM. In one patient additional irrigated RF current catheter touch-up was needed, because of pinhole balloon rupture to achieve complete isolation of the right superior (RS) and right inferior (RI) pulmonary vein (PV). A total of 12 pinholes were detected. During the first four procedures 6 of 12 (50%) pinholes occurred. 162/182 (89%) of PVs showed PVI after the first application of a circular lesion around the PVs. Median procedure time was 110 (100, 132) minutes, while the median fluoroscopy time was 18 (15, 24) minutes. Periprocedural complications occurred as follows: one (2.2%) pericardial tamponade requiring epicardial puncture was detected, that was not related to the utilization of the VGLB system. Furthermore two cases (4.4%) with an asymptomatic pericardial effusion, not requiring pericardial puncture were detected. All patients recovered without any sequelae. One patient (2.2%) experienced phrenic nerve palsy during ablation of the RSPV. No periprocedural stroke, or atrioesophageal fistula were observed.

Conclusion: The Excalibur ^TM system was effective for PVI even for operators without any previous experience in VGLB ablation. Although the increased compliance of the system may improve the visibility of the PVs during the procedures a relatively high rate of pinhole ruptures has been observed. Further investigation is necessary to draw final conclusions and to judge on safety and efficacy of this new promising system.