Myocarditis, due to the heterogeneity of manifestations and, quite often, the course unpredictability, is one of the most difficult for timely diagnosis of disease groups in modern cardiology. At the same time, myocardial inflammatory diseases often have a severe course, requiring hospitalization, monitoring and treatment in the in tensive care unit, mechanical circulatory support, temporary cardiac pacing, artifi cial ventilation, renal replacement therapy, etc. The paper presents the experience of treating patients admitted to the Kommunarka Multidisciplinary Clinical Center with acute left ventricular failure and arrhythmias caused by myocarditis of vari ous origin. The approach to initial therapy and differential diagnosis is described. © 2025, Silicea-Poligraf. All rights reserved.