Optimal diameter of the pulmonary vein ostium for second-generation 28-mm cryoballoon ablation of atrial fibrillation.

Background: Large pulmonary veins (PVs) have the risk of excessive cooling when the cryoballoon is moved into them, whereas smaller PVs may not be isolated because of insufficient balloon-tissue contact. We previously reported that the effective nadir balloon temperature (NBT) was <- 44°C for predicting early PV reconnections. However, the ideal PV and left atrial (LA) diameters for cooling temperatures during cryoballoon ablation (CBA) are unknown.

Methods: We measured the PV ostium (PVos) and LA diameters on computed tomography images in 71 atrial fibrillation patients who underwent a 28-mm CBA. We defined -60°C ≤ NBT <- 44°C as the optimal NBT. The optimal PVos diameters and elliptical area were determined using the receiver operating characteristic curve cutoff values for the optimal NBT.

Results: The maximum PVos diameter (PVmax), minimum PVos diameter (PVmin), and PV elliptical area correlated negatively with the NBT (PVmax: r = -.34, P < .0001; PVmin: r = -.41, P < .0001; PV elliptical area: r = -.41, P < .0001). Based on the NBT-derived definition, the optimal PVmax, PVmin, and PV elliptical area were 19 < PVmax ≤ 21 mm, 14 < PVmin ≤ 16 mm, and 186.83 < PV elliptical area ≤ 254.34 mm , respectively. In addition, a positive correlation between the LA longitudinal diameter and NBT was observed in the right superior PV (r = .34, P = .004), and the LA transverse diameter correlated inversely with the NBT in the left inferior PV (r = -.34, P = .004).

Conclusions: We identified the optimal PV diameters and elliptical area to establish the optimal NBT during the second-generation 28-mm CBA. These data will help for the preclinical judgment for a successful CBA.