Left atrial size is a critical factor for selection of the optimal catheter ablation system for pulmonary vein isolation - pulsed field ablation or cryoballoon?

Background Anatomy and size of the left atrium (LA) are important factors influencing performance of pulmonary vein isolation (PVI) procedures, especially when using single-shot devices. Due to unfavourable angles in enlarged atria, achievement of pulmonary vein (PV) occlusion may be challenging using cryoballoon (CB) systems. In smaller atria, there is sometimes less space for placing the device on the PV. Both situations may result in prolonged procedural and fluoroscopy times (FT). Purpose The aim of this study was to determine which catheter system is most suitable for different atrial sizes. Methods We retrospectively analysed data from a cohort of 305 consecutive patients undergoing PVI between 11/2023 and 09/2024, including 206 with paroxysmal and 99 with persistent atrial fibrillation. Patients were divided into three groups: group A (n=210) were ablated with a CB catheter, group B (n=50) with a pentaspline pulsed field ablation (PFA) catheter, and group C (n=45) with a circular PFA catheter. The LA dwell time, and the required FT were chosen as surrogate parameters for procedural feasibility. Values are shown as median [IQR]. Results PVs were isolated in all patients. Groups B and C demonstrated shorter LA dwell times compared to group A (46 [37-55.3] min and 53 [44.5-61.5] min vs. 58.5 [50-70.3] min; p<0.001 and p=0.006, respectively). This effect was particularly evident for enlarged LA (40.5 [33-52] min and 55.5 [46-66.3] min vs. 61.5 [52-74.5] min; p=0.001 and p=0.037, respectively). In normal-sized LA an advantage was observed only for group B but not for group C vs. group A (46.5 [38-56] min and 48 [43-58] min vs. 55.5 [48-66] min; p<0.001 and p=0.074, respectively). In contrast, groups B and C required more FT than group A (12.3 [9-14.5] min and 11.28 [9.7-13.7] min vs. 9.0 [6.6 12.4] min; p<0.001 and p=0.002, respectively). This was more apparent in normal-sized LA (12.4 [9.1-14.5] min and 10.6 [10.1-13.1] min vs. 8.2 [6.2-10.5] min; p<0.001 and p=0.008, respectively). For enlarged LA, there was no difference in FT between the groups. Further analyses showed that an enlarged LA in group A was associated with longer LA dwell and fluoroscopy times (enlarged vs. normal-sized LA: LA dwell time 61.5 [52-74.5] min vs. 55.5 [48-66] min, p=0.011; FT 9.7 [7.7-13.2] min vs. 8.2 [6.1-10.5] min, p=0.001). This effect was not evident for patients in groups B and C. Conclusion In enlarged LA, both PFA systems showed shorter LA dwell times without adverse FT compared to the CB system. Due to the difficulty in sufficiently occluding PVs with the CB in some patients with dilated LA, the PFA systems appear to be the better alternative. In normal-sized LA the CB system appears to be more favourable with a lower radiation exposure, especially compared to the pentaspline catheter. A reason for the increased radiation exposure in PFA systems may be attributed to the more frequent repositioning of the PFA devices.