The treatment of fulminant myocarditis with immunomodulatory therapies adapted to specific subtypes may improve outcomes for patients. A scientific statement published in Circulation and endorsed by the Heart Failure Society of America and the Myocarditis Foundation provides resources for the management of the broad spectrum of fulminant myocarditis.

According to researchers, signs and symptoms of fulminant myocarditis range from infection or inflammatory disorder, dyspnea, and arrhythmias, to sudden death. Low QRS voltage, ST-segment elevations, PR-segment depression, ventricular arrhythmias, and conduction abnormalities may be indicative of fulminant myocarditis on electrocardiograms, which can be associated with elevated serum cardiac troponin, a useful indicator of the early stages of the disease. Natriuretic peptides, erythrocyte sedimentation rate, and C-reactive protein levels can also be leveraged in diagnosing myocarditis.

Echocardiography is the most used initial diagnostic test to assess fulminant myocarditis and can help assess the level of cardiac compromise, as it allows to evaluate left ventricle wall thickness, pericardial effusion, diastolic dysfunction, right ventricular dysfunction, and cardiac thrombus, all of which can be used to monitor progression, and establish a prognosis. Gadolinium contrast-enhanced cardiac magnetic resonance can also be used to assess myocardial edema and fibrosis. Contrast-enhanced cardiac computed tomography may be used to evaluate coronary artery disease, and extracellular volume fraction mapping may serve as an adjunct diagnostic biomarker. Nuclear imaging tools may be used to evaluate perfusion defects, and positron emission tomography, to evaluate myocardial metabolism and inflammation.

According to researchers, endomyocardial biopsy can also help diagnose and assess subtypes of fulminant myocarditis. This test should be performed if heart failure is unexplained, associated with hemodynamic compromise, recent (ie, <2 weeks), occurs at a 2 to 3-week frequency, or is associated with a dilated left ventricle, new bradyarrhythmia, or new ventricular arrhythmias. Endomyocardial biopsy accuracy can be improved when combined with imaging.

Initial management and stabilization are essential to increase the likelihood of recovery and survival. Patients often present with cardiogenic shock, arrhythmia, bradyarrhythmia caused by heart block, sudden cardiac death, and syncope. Initial management should focus on resuscitation and stabilization, which may include hemodynamic and respiratory support. Initial testing should include measurement of venous blood gas for pH, lactate, complete blood count, basic metabolic panel, and the presence of cardiac biomarkers. In many cases, extracorporeal life support is the quickest way to stabilize patients with fulminant myocarditis, after which, neurohormonal antagonist therapy and diuretics should be initiated.

Lymphocytic myocarditis is a clinicopathological disorder that leads to heart inflammation with histological and immunohistochemical findings. Giant cell myocarditis most often affects young and middle-aged adults, and most commonly presents as acute heart failure with ventricular arrhythmias and progressive hemodynamic deterioration. Both conditions are autoimmune. Acute necrotizing eosinophilic myocarditis affects mainly adolescents and adults with the most common presentation being heart failure or sudden cardiac arrest with ventricular thrombosis and arterial emboli. This subtype is most commonly caused by drug hypersensitivity, but some cases are associated with hypereosinophilic syndrome, granulomatous polyangiitis, and other causes of systemic eosinophilia. Cardiovascular toxicity can also be caused by immune checkpoint inhibitors used in new cancer therapies.

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“Understanding the fundamental biology leading to a given autoimmune response will help us learn how to more precisely treat these potentially deadly syndromes with a high degree of specificity,” noted the statement authors.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Kociol RD, Cooper LT, Fang JC, et al. Recognition and initial management of fulminant myocarditis: a scientific statement from the American Heart Association [published online January 6, 2020]. Circulation. doi: 10.1161/CIR.0000000000000745