Anatomical and Procedural Factors of Severe Pulmonary Vein Stenosis After Cryoballoon Pulmonary Vein Ablation.

ABSTRACT

OBJECTIVES: This study examined the anatomical or procedural factors associated with severe pulmonary vein (PV) stenosis after cryoballoon PV isolation. BACKGROUND: PV stenosis is a complication associated with cryoballoon ablation. METHODS: The study included 170 consecutive patients with paroxysmal atrial fibrillation who underwent cryoballoon ablation. In addition to factors generally considered to be related to the occurrence of PV stenosis (PV size, cryoballoon application number and time, and minimum freezing temperature), we evaluated the following 4 factors 1) depth of balloon position; 2) the PV angle (internal angle between each PV and horizontal line); 3) noncoaxial balloon placement (hemispherical occlusion); and 4) contact surface area between the cryoballoon and the PV wall (defined as the balloon contact ratio). RESULTS: Severe PV stenosis (≥75% area reduction) was observed in 9 (1.3%) PVs (6 left superior and 3 right superior PVs) in 9 patients. The PV size, cryoballoon application number and time, minimum freezing temperature, and the depth of cryoballoon position were not significantly associated with occurrence of severe PV stenosis, but the PV angle was significantly smaller in PVs with severe stenosis than it was in those without stenosis (25.6 ± 9.7° vs. 34.2 ± 6.4°; p < 0.001). Hemispherical occlusion was more frequently observed and balloon contact ratio was larger in PVs with severe stenosis (55.6% vs. 14.8%; p = 0.049) than in those without stenosis (0.70 ± 0.06 vs. 0.54 ± 0.08; p < 0.001). CONCLUSIONS: A horizontally connecting PV, noncoaxial placement of cryoballoon, and a larger contact surface area of the cryoballoon were predictors of the occurrence of severe PV stenosis after cryoballoon ablation.