Objective. To evaluate clinical, anamnestic, diagnostic and intraoperative data before and during cryoballoon isolation of the pulmonary vein orifices of the left atrium in patients with various forms of atrial fibrillation (AF) and comorbid pathology. Material and methods. A total of 284 patients who met the selection criteria were included in the study. The average follow-up period was 18.4 ± 1.8 months. Depending on the form and duration of AF paroxysms, documented by electrocardiogram and Holter monitoring, the patients were divided into two groups. Group 1 included 170 (59.8%) patients with paroxysmal AF, and group 2 included 114 (40.2%) patients with persistent AF. A statistically significant difference was revealed when analyzing the arrhythmological history of AF: 12.3 ± 2.2 weeks in patients with paroxysmal AF and 25.7 ± 3.28 weeks in those with persistent AF (p = 0.001). Results. When analyzing preoperative echocardiographic data, a significant difference was found in the parasternal (anteroposterior) size of the left atrium (LA) between patients with paroxysmal and persistent forms of AF 44 [43–46] and 46 [44–47], respectively (p < 0.001), peak atrial longitudinal strain (PALS) of LA – in patients with the paroxysmal form was 29.8 [28.6–32.3], and with the persistent form 18.85 [14.9– 26.12] (p < 0.001). According to multispiral computed tomography data, the most significant difference was found when assessing the volume of the LA taking into account the appendage 110 [102–118] in group 1 and 140 [130–155] in group 2 (p < 0.001) and indexed LA volume 54.3 [51.5–58.7] in the paroxysmal form and 67.8 [63.7–72.1] in the persistent form (p < 0.001). During cryoballoon isolation (CBI) of the pulmonary vein (PV) orifices, 1101 (96.9%) of 1136 pulmonary veins were isolated, while in 14 PVs (2.8%) it was not possible to position the cryoballoon in the PV, which in turn was associated with the anatomical features of the location of the PV in the LA. When analyzing the data obtained during the performance of CBI of the PV orifices, reliable differences were established in patients with paroxysmal and persistent forms of AF between the following parameters: the average duration of the operation of 90 [85–100] and 105 [90–110] min, as well as the average duration of the main stage of the operation (left atrial stage) of 35 [30–40] and 40 [35–40] min (p = 0.001 and p = 0.001, respectively). Conclusion. Conducting this analysis allows us to analyze the mechanism of development of more persistent forms of atrial fibrillation. In particular, the development of more stable persistence is influenced by an increase in volume (anatomical remodeling), a decrease in contractility (mechanical) and an increase in fibrously altered atrial myocardium (electrical).