The aim – to determine clinical and echocardiographic variables that can be useful for prognosis of 6 months sinus rhythm maintenance and evolution of atrial fibrillation (AFib) into permanent form in patients with episode of persistent non-valvular AFib. Consecutive 103 patients underwent transesophageal, transthoracic echocardiography and clinical examination before cardioversion. All patients were observed for recurrence of AFib episode after cardioversion and development of permanent AFib (50 % percentile of follow up 596 days, maximum 1519 days). We found that recurrence of persistent AFib during 6 months was registered in 58.25 % of patients and permanent AFib occurred in 36.9 % of patients during follow up. Female gender, left ventricle ejection fraction < 40 %, CHA2DS2-VASc ≥ 4, Se < 6 cm/s were significantly associated with recurrence of persistent arrhythmia during 6 months. Left ventricle ejection fraction < 40 % and Е/Еm ≥ 10 were the only independent predictors for evolution of AFib into permanent form.