Objective To the date, catheter ablation basing on pulmonary vein (PVs) isolation is effective treatment for paroxysmal atrial fibrillation (PAF). In some experimental electrophysiological center, catheter ablation has been the first line for PAF. The aim of this study is to compare the variation of ostia, the antrum volume of pulmonary veins and the left atrial volume in patients with and without PAF.

Methods We consecutively enrolled 28 and 35 patients with and without PAF (PAF group and control group). All the patients were taken intravenous injection of contrast medium before evaluated by 16-slice CT (MSCT). The 3D reconstruction of PVs and left atrium was transformed into AW4.2 system, and calculated the variation of pulmonary veins by Cardiac IQ software. Diameters of PVs ostia were measured by virtual endoscopy. The antrum volume of PVs and the left atrium volume were calculated by volume rendering.

Results 3 patients (10.7%) with PAF had common ostia or trunk of PVs and right middle PVs, respectively. We compared the maximum and minimum diameter of PVs ostia in PAF group with that in control group as follows: the maximum diameters, left superior PVs (22.69±3.56 vs 18.69±2.15 mm, p<0.01), left inferior PVs (18.40±2.50 vs 16.96±2.07 mm, p<0.05), right superior PVs (20.78±3.46 vs 19.26±2.55 mm, p=0.08), right inferior PVs (20.19±4.39 vs 16.90±1.75 mm, p<0.01); the minimum diameter, left superior PVs (16.18±3.60 vs 11.12±2.55 mm, p<0.01), left inferior PVs (11.1±3.20 vs 10.40±2.10 mm, p<0.01), right superior PVs (16.18±2.57 vs 13.61±2.35 mm, p<0.01), right inferior PVs (16.26±3.16 vs 13.29±2.20 mm, p<0.01). The atrium volume of the bilateral PVs in PAF group was significantly larger than that in the control group (left, 3.53±0.74 vs 2.74±0.49 cm³, p<0.01; right, 4.57±1.59 vs 3.54±1.01 cm³, p<0.01). The left atrial volume in PAF group was also significantly larger than that in control group (99.83±15.68 vs 88.24±18.21 cm³, p<0.05). The atrium volume of bilateral PVs justified with left atrial volume had no significant difference between the two groups.

Conclusion The ostial diameter and atrium volume of PVs were increased significantly, leading to the change for anatomy of atrial sleeves and distribution of autonomic nerve, and caused reentry or focal automaticity around PVs, which eventually initiated PAF. This study suggests that patients with PAF may exist potential structural disease of atria.