Sudden cardiac death in myocarditis

Abstract

According to statistics, myocarditis is one of the leading causes of sudden cardiac death (SCD) in children and young adults. The etiology of myocarditis includes infectious and non-infectious, including autoimmune diseases, as well as toxicities and hypersensitivity to various drugs or bites of insects, spiders, snakes, etc. The risk of myocarditis among patients with COVID-19 is 15.7-fold higher than that in the general population. The most common cause of death in myocarditis is heart arrhythmia, such as ventricular tachyarrhythmia, ventricular fibrillation, or severe bradycardia. Genetic predisposition, ion and metabolic disorders, mechanisms of autoimmune response, and direct cardiotoxic action in viral diseases play a role in the pathophysiology of inflammatory myocardial damage. While the majority of patients with myocarditis, who died suddenly, was asymptomatic or had few symptoms, a timely and accurate diagnosis of myocarditis seems to be an important challenge for prevention or minimization of SCD risk. Nonetheless, at present there is no convincing evidence of an association between laboratory and instrumental parameters and the SCD risk in such patients. Endomyocardial biopsy remains the "golden standard" in the diagnosis of myocarditis. Biomarkers (troponins or creatine phosphokinase) are not highly specific. The most common electrocardiographic findings in myocarditis are sinus tachycardia and nonspecific changes in the ST-T segment. The presence of Q wave, bundle branch block, Brugada syndrome, shortened or prolonged QT interval, and early ventricular repolarization are associated with an increased risk of SCD in myocarditis. Given the absence of specific echocardiographic signs of myocarditis, special attention is paid to the assessment of the size of the cardiac chambers, wall thicknesses, global and regional systolic and diastolic function of both the left and right ventricles, visualization of pericardial effusion and intracardiac thrombi. A combined cardiac magnetic resonance imaging using T2-weighted imaging and early and late gadolinium enhancement provides high diagnostic accuracy and seems to be a useful tool in the stratification of patients with suspected acute myocarditis. With the established etiology of myocarditis, specific therapy is necessary to eliminate the pathogen. It is necessary to take into account the likely arrhythmogenic effects of the drugs used in treatment. Non-steroidal anti-inflammatory drugs are generally not indicated in patients with myocarditis because they cause renal impairment and sodium retention, which can exacerbate left ventricular dysfunction and increase the risk of SCD. In the case of severe conduction disturbances and ventricular tachyarrhythmias, implantation of a pacemaker or cardioverter-defibrillator is necessary.