MYOCARDITIS: EPIDEMIOLOGY, DIAGNOSIS, THERAPY

Аннотация

Myocarditis is an uncommon, potentially life-threatening disease that presents with a wide range of symptoms in children and adults. Viral infection is the most common cause of myocarditis in developed countries, but other etiologies include bacterial and protozoal infections, toxins, drug reactions, autoimmune diseases, giant cell myocarditis and sarcoidosis. Acute injury leads to myocyte damage, which in turn activates the innate and humeral immune system, leading to severe inflammation. In most patients, the immune reaction is eventually down-regulated and the myocardium recovers. In select cases, however, persistent myocardial inflammation leads to ongoing myocyte damage and relentless symptomatic heart failure or even death. The diagnosis is usually made based on clinical presentation and noninvasive imaging findings. Most patients respond well to standard heart failure therapy, although in severe cases, mechanical circulatory support or heart transplantation is indicated. Prognosis in acute myocarditis is generally good except in patients with giant cell myocarditis. Persistent, chronic myocarditis usually has a progressive course but may respond to immunosuppression. Keywords: Protozoal infections, giant cell myocarditis and sarcoidosis, myocyte damage, heart failure, chronic myocarditis, immunosuppression. Intraduction In 1753, inflammation of the heart and the difficulty in discerning such was described by a physician, Jean Baptiste Senac in Versailles, France, in his work entitled Traité des Maladies du Coeur (Treatise on Disease of the Heart). The term myocarditis was ultimately coined by Joseph Freidrich Sobernheim in 1837; however, the use of this term included other cardiomyopathies that were previously undocumented including ischemic heart disease and hypertensive heart disease. It was not until the 1980s that the World Health Organization and the International Society and Federation of Cardiology attempted to differentiate between myocarditis and other cardiomyopathies. 1 In general, myocarditis is identified as an inflammatory disease of the heart muscle cells and is pathologically identified by conventional histology and immunohistochemical techniques as an infiltration of mononuclear cells to the myocardium. Myocarditis can be acute, subacute, or chronic and may either involve focal or diffuse areas of the myocardium. A recent update to the definition of myocarditis has been discussed by Caforio et al in defining myocarditis, using immunohistochemical data, as individuals who exhibit ≥13 lymphocytes/mm2 including ≤4 monocytes/mm2 with the presence of CD3-positive T lymphocytes ≥7 cells/mm2. This definition uses immunohistochemical data that require endomyocardial biopsy (EMB) collection and thus is limited to a relatively smaller cohort of patients or postmortem autopsy samples. Moreover, although this definition of myocarditis has been widely accepted, it lacks information on the complexity of cellular infiltrates such as macrophage subtypes (classical/intermediate/nonclassical), effector (Th1/Th2/Th17), and regulatory (FoxP3+/CD4+) T-lymphocyte subtypes, and thus fails to differentiate a profibrotic response from a healing inflammatory response. Transcriptome-based analysis of biopsies may further our definition of myocarditis. 1064 ResearchBib IF - 11.01, ISSN: 3030-3753, Volume 2 Issue 5 Epidemiology Before the Covid-19 pandemic, the estimated global incidence of myocarditis was 1 to 10 cases per 100,000 persons per year. The highest risk was among people between 22 and 44 years of age and among men. In the 35-to-39-year-old age group, the rate was 6.3 cases per 100,000 men and 4.6 cases per 100,000 women, with similar rates in the 20-to-44-year-old age group.The increased use of cardiac MRI has led to a gradual rise in the reported incidence of myocarditis in the United States, from 9.8 to 14.6 cases per 100,000 persons. Precise data on the burden of myocarditis are available only for selected clinical settings. For instance, the incidence of myocarditis among patients with heart failure varies from 0.6% to 5.0% according to age and region. Among patients with chest pain who were seen in the emergency department, 3% had acute myocarditis and pericarditis. A diagnosis of myocarditis was made on the basis of cardiac MRI in one third of patients with a previous diagnosis of acute myocardial infarction and nonobstructed coronary arteries. Autopsy studies in young people who died suddenly have shown a variable incidence of myocarditis. The incidence was 14% in the prospective registry of northeastern Italy.Among patients with advanced cancers who were treated with immune checkpoint inhibitors, the incidence was 1.18%.During the Covid-19 pandemic, 2.6 cases of definite or probable myocarditis and 4.1 cases of definite, probable, or possible myocarditis have been reported per 1000 patients hospitalized for Covid-19.Finally, analysis of currently available data on Covid-19 messenger RNA (mRN