Recurrent automatic atrial tachycardia can induce dilated cardiomyopathy. We present clinical and therapeutic problems of 16 years old male with ectopic left atrial tachycardia refractory to pharmacological therapy. In this patient long periods of atrial tachycardia 200-240/min due to lack of effective medication caused cardiac failure. Uncontrolled taking of various antiarrhythmic drugs and persistent tachycardia led to cardiogenic shock. The electrophysiologic study revealed focus of the tachycardia localized in the area of left cardiac auricle. The rate of the tachycardia was changing from 84 to 240/min, with periods of Mobitz I block in the AV node. In periods of 1:1 AV conduction the tachycardia had sometimes LBBB QRS morphology. The atrial tachycardia provoked unsustained ventricular one. The patient was operated. Resection of left auricle and mitral valvuloplasty were performed. After the operation the patient regained undisturbed sinus rhythm and symptoms of heart failure disappeared.