Impact of Right Superior Pulmonary Vein Anatomy and 31‐mm Cryoballoon Use on the Risk of Phrenic Nerve Injury During Cryoablation for Atrial Fibrillation

BACKGROUND: Phrenic nerve injury (PNI) is a common complication of cryoballoon pulmonary vein isolation, especially during right superior pulmonary vein (RSPV) ablation. The impact of a newly introduced size-adjustable 31-mm cryoballoon on PNI and its anatomical predictors remain unclear. METHODS AND RESULTS: This retrospective study included 249 patients who underwent first-time cryoballoon ablation with successful RSPV isolation: 153 with a conventional 28-mm balloon and 96 with a size-adjustable balloon in the 31-mm configuration. Preprocedural computed tomography assessed RSPV anatomical features, including ostial diameters, cross-sectional area, and the RSPV-left atrium (LA) angle, defined as the angle between the RSPV and anterolateral LA wall on axial slices. The overall incidence of PNI did not differ between groups (28-mm: 10%; 31-mm: 15%; p = 0.330). However, persistent PNI, defined as dysfunction beyond the procedure, occurred only in the 28-mm group (5%). Multivariate analysis showed that the RSPV-LA angle independently predicted PNI in both groups (28-mm: odds ratio 3.819, 95% confidence interval 1.825-7.926, p < 0.001; 31-mm: odds ratio 3.633, 95% confidence interval 1.538-8.594, p = 0.003). No other anatomical parameters showed consistent associations. CONCLUSION: The RSPV-LA angle is a robust anatomical predictor of PNI during RSPV cryoballoon ablation, regardless of balloon size. Use of the 31-mm cryoballoon may help to reduce the risk of persistent PNI.