Background-In contrast with traditional radiofrequency ablation, little is known about the influence of cryoballoon ablation on the morphology of pulmonary veins (PVs). We evaluated the influence of cryoballoon ablation on the PV dimension (PVD) and investigated the factors associated with a reduction of the PVD. Methods and Results-Seventy-four patients who underwent cryoballoon ablation for paroxysmal atrial fibrillation were included in the present study. All subjects underwent contrast-enhanced computed tomography both before and at 3 months after the procedure. The PVD (cross-sectional area) was measured using a 3-dimensional electroanatomical mapping system. Each PV was evaluated according to the PVD reduction rate (ΔPVD), which was calculated as follows: (1−post-PVD/pre-PVD)×100 (%). Ninety-two percent of the PVs (271/296) were successfully isolated only by cryoballoon ablation; the remaining 8% of the PVs required touch-up ablation and were excluded from the analysis. Mild (25%-50%), moderate (50%-75%), and severe (≥75%) ΔPVD values were observed in 87, 14, and 3 PVs, respectively, including 1 case with severe left superior PV stenosis (ΔPVD: 94%) in a patient who required PV angioplasty. In multivariable analysis, a larger PV ostium and lower minimum freezing temperature during cryoballoon ablation were independently associated with PV narrowing (odds ratio, 1.773; P=0.01; and odds ratio, 1.137; P<0.001, respectively). Conclusions-A reduction of the PVD was often observed after cryoballoon ablation for atrial fibrillation. A larger PV ostium and lower minimum freezing temperature during cryoballoon ablation were associated with an increased risk of PVD reduction.

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Objectives One of the mechanisms of early recurrence of atrial fibrillation (ERAF) after AF ablation is considered to be the inflammatory reaction of the atrial tissue. The aim of this study is to compare the clinical significance of ERAF at each stage for true AF recurrence between cryoballoon (CB) and radiofrequency (RF) ablation. Methods Among 798 paroxysmal AF patients who underwent an initial ablation, 460 patients (CB, n = 230; RF, n = 230) were selected by propensity score matching. Very ERAF (VERAF), ERAF-1M, ERAF-3M and true AF recurrence were defined as AF recurrence at 0–2, 3–30, 31–90 days and more than 90 days after the procedure, respectively. Results The patient characteristics of the two groups were similar. ERAF was observed 21% and 27% in the CB and RF groups, respectively. In both the CB and RF group, VERAF, ERAF-1M and ERAF-3M were more frequently observed in patients with true AF recurrence than in those without. In a multivariable analysis, ERAF-1M and ERAF-3M were found to be independent predictors of true AF recurrence in both the CB (P = 0.04 and P<0.001, respectively) and RF groups (P = 0.02 and P = 0.001, respectively). However, while VERAF was associated with true AF recurrence after RF ablation (P = 0.03), it was not associated with true AF recurrence after CB ablation (P = 0.19). Conclusion The relationship between ERAF and true AF recurrence differed between the RF and CB ablation groups. While VERAF was associated with true AF recurrence after RF ablation, it was not a predictor of true AF recurrence after CB ablation.

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