Atrial fibrillation (AF) is a supraventricular arrhythmia characterized by chaotic contraction of the atrial myocardium with a frequency of 350 to 700 bpm and irregular conduction to the ventricular myocardium. Worldwide, AF is the most common arrhythmia, according to preliminary data, from 5 to 7% of the population suffer from this disease. The search for optimal tactics for treating patients has been going on for several decades. At this moment there are medical, interventional and surgical directions in the treatment of AF. A new stage in the treatment was the emergence of the Maze procedure, which today is the "gold standard" in the surgical treatment of AF in patients with concomitant valvular pathology. According to various sources, the effectiveness of the Maze procedure reaches 90–95%. However, in a certain number of patients, the appearance of incisional arrhythmias is observed. This clinical case demonstrates the successful elimination of atypical incisional left atrial flutter using nonfluoroscopic high-density mapping in a patient after successful elimination of long-term persistent AF by cryomodification of the Maze procedure.