In a significant proportion of patients, atrial fibrillation and other arrhythmias develop some time after surgical treatment of valvular heart defects. Incisional atrial tachycardia significantly worsens the hemodynamics of the heart in the postoperative period. Taking into account the difficulties in treatment, resistance to antiarrhythmic therapy and, in this regard, the urgency of the problem of incisional cardiac arrhythmias, we present this clinical case. Patient 68 years old, was admitted to the clinic with complaints of rapid heartbeat. Laboratory methods of research – all indicators within the physiological norm. The patient was taken to the X-ray surgery on the rhythm of atrial flutter. The ablation electrode was transferred to the left atrium (LA), and the activation and amplitude maps of the left atrium were constructed. Critical areas of arrhythmia, as well as the "early meets late" zones, are recorded along the anterior wall. In this zone, linear radiofrequency exposure was performed, followed by restoration of the sinus rhythm. The presented clinical case may be of interest, due to the fact that the detected complex rhythm disturbances localized along the anterior wall of the LA, in the area of the mitral valve cuff, were successfully eliminated by linear radiofrequency ablation.