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 2 , 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.