Cryoballoon ablation of the pulmonary vein ostia is a causative treatment of atrial fibrillation. The senes of publications included in the PhD thesis, analyzed in detail the clinical context of the qualified patients, the course of the procedure and the prognosis after ablation. The local protocol of pre- and postoperative care developed over the years as well as a detailed practical description of the procedure itself are presented. The long-term effectiveness of the procedure was analyzed, as well as the possibility of sequential use of two single-application techniques in the case of reablation after recurrence of atrial fibrillation. The most important clinical factors related to the long-term ineffectiveness of cryoablation were investigated - the fmal result was the creation of a orginal risk scale of atrial fibrillation recurrence after isolation of the pulmonary ostia - 0-1-2 PL Score. Based on the transthoracic and transesophageal echocardiographic examination, the relationship between postoperative atrial fibrillation recurrence and left atrial enlargement, the presence of a patent foramen ovale and a reduced value of the left atrial appendage emptying flow velocity was established. The senes of publications provides a clinically useful compendium of knowledge of cryoballoon ablation for both ablationists and physicians who take outpatient care of ; patients with atrial fibrillation.