What does this research mean for the field?

Using the 31 mm cryoballoon size achieves complete pulmonary vein occlusion in significantly more patients (70.7%) than the 28 mm size (56.7%), particularly in superior veins. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

The study aims to determine the optimal cryoballoon size for effective pulmonary vein occlusion during ablation procedures for atrial fibrillation by identifying anatomical predictors.

March 9, 2026Open Access

Anatomical Predictors of Optimal Cryoballoon Size Selection: A Prospective Comparison of 28 mm Versus 31 mm Size‐Adjustable Balloon Modes

Key Result

Using the 31 mm cryoballoon size achieved complete pulmonary vein occlusion in 70.7% of patients versus 56.7% with the 28 mm size, especially in superior veins.

Key Points

The study aims to determine the optimal cryoballoon size for effective pulmonary vein occlusion during ablation procedures for atrial fibrillation by identifying anatomical predictors.
Prospective study involving 150 patients undergoing cryoballoon ablation for atrial fibrillation.
Assessment of pulmonary vein occlusion grades using contrast injection for both 28 mm and 31 mm balloon sizes.
Computed tomography measurements taken pre-procedure included pulmonary vein dimensions and associated anatomical factors.
Generalized Estimating Equations analysis was employed to account for within-patient correlations.
Complete occlusion achieved in 70.7% with 31 mm versus 56.7% with 28 mm (p = 0.016).
Superior pulmonary veins showed higher occlusion rates compared to inferior veins with significant differences in 31 mm mode.
Identification of independent predictors of occlusion including balloon size, pulmonary vein diameter, ovality index, and trunk length.
Only 3.3% of patients required different balloon sizes for different pulmonary veins.

Structured PICO

Does the 31 mm cryoballoon mode improve pulmonary vein occlusion compared to the 28 mm mode in patients undergoing ablation for atrial fibrillation?

Population

150 consecutive patients undergoing cryoballoon ablation for atrial fibrillation

Intervention

31 mm size-adjustable cryoballoon mode (POLARx FIT)

Comparator

28 mm size-adjustable cryoballoon mode (POLARx FIT)

Outcome

Complete pulmonary vein (PV) occlusion assessed using contrast injectionsurrogate

The 31 mm cryoballoon mode significantly improves pulmonary vein occlusion rates compared to the 28 mm mode, particularly in superior pulmonary veins.

Main Result

Absolute Event Rate: 0% vs 0%

Abstract

ABSTRACT Background 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. Methods 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. Results 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. Conclusion 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.