Anatomical Predictors of Optimal Cryoballoon Size Selection: A Prospective Comparison of 28 mm Versus 31 mm...

Complete pulmonary vein (PV) occlusion is critical for successful cryoballoon ablation. The POLARx FIT size-adjustable cryoballoon adjusts diameter from 28 to 31 mm. This study aimed to compare PV occlusion grades between balloon modes and identify anatomical predictors for optimal size selection.

This prospective study included 150 consecutive patients undergoing cryoballoon ablation for atrial fibrillation. PV occlusion was assessed using contrast injection (Grades I-IV) for both balloon sizes before ablation. Pre-procedural computed tomography measurements included PV dimensions, ovality index, trunk length, and PV angles in frontal and transversal planes. Generalized Estimating Equations analysis accounted for within-patient correlation.

Complete occlusion in all four PVs was achieved in 106/150 patients (70.7%) with 31 mm versus 85/150 (56.7%) with 28 mm mode (p = 0.016). Superior PVs demonstrated significantly higher occlusion rates (LSPV: 97.3% vs. 88.7%, p = 0.0002; RSPV: 93.3% vs. 71.3%, p < 0.0001), while inferior PVs showed no significant difference (LIPV: p = 1.000; RIPV: p = 0.070). GEE analysis identified 31 mm mode (OR 2.41, p < 0.001), smaller PV diameter (OR 0.59, p < 0.001), lower ovality index (OR 0.60, p < 0.001), and longer trunk length (OR 1.49, p = 0.001) as independent predictors of complete occlusion. Post hoc analysis revealed 3.3% of patients required different balloon sizes across their PVs. Acute PV isolation was achieved in all targeted PVs.

The 31 mm mode significantly improves occlusion rates, particularly in superior PVs, while 28 mm is adequate for inferior PVs. Larger PV diameter and higher ovality index predict incomplete occlusion, supporting preferential use of 31 mm mode for larger, more oval PVs. Validation in multicenter cohorts is required.