What is the diagnosis and treatment for infectious myocarditis (inflammation of the heart muscle)?

From the Guidelines

Infectious myocarditis is typically diagnosed using a combination of clinical presentation, electrocardiogram (ECG), echocardiogram, cardiac biomarkers, and cardiovascular magnetic resonance (CMR) imaging, and treatment usually involves supportive care, with avoidance of strenuous exercise and nonsteroidal anti-inflammatory drugs (NSAIDs), and consideration of immunosuppression in specific cases.

Diagnosis

• The diagnosis of infectious myocarditis is based on the presence of cardiac symptoms, elevated cardiac biomarkers (such as troponin), and abnormal findings on ECG, echocardiogram, CMR, or histopathologic examination 1.
• CMR is a sensitive and non-invasive test for confirming acute myocarditis, and can identify myocardial edema, necrosis, and inflammation 1.
• Endomyocardial biopsy remains the gold standard for definitive diagnosis, especially in patients with a life-threatening course of the disease 1.

Treatment

• Treatment of infectious myocarditis typically involves supportive care, with a focus on managing symptoms and preventing complications 1.
• Patients with acute myocarditis should avoid strenuous exercise for 3 to 6 months after diagnosis, and competitive sport participation should be avoided until clinical evaluation and functional testing indicate it is safe to resume 1.
• NSAIDs should be avoided due to the risk of increased inflammation and mortality 1.
• Immunotherapy may be considered in specific cases, such as giant cell myocarditis or eosinophilic myocarditis, but is not generally recommended for acute lymphocytic myocarditis in adults 1.
• Guideline-directed medical therapy for heart failure should be initiated and continued after discharge in patients with myocarditis and heart failure symptoms 1.

From the Research

Diagnosis of Infectious Myocarditis

• The diagnosis of infectious myocarditis can be suggested by presenting symptoms, elevated biomarkers such as troponins, electrocardiographic changes of ST segments, and echocardiographic wall motion abnormalities or wall thickening 2.
• Cardiac magnetic resonance imaging is non-invasive and is the gold standard for diagnosis and clinical follow-up of these patients 3, 4.
• Endomyocardial biopsy as an invasive method is the diagnostic choice in life-threatening cases with suspicion of fulminant myocarditis where the diagnosis has not yet established or there is no adequate response to the applied therapeutic regimen 3, 4.

Treatment of Infectious Myocarditis

• The treatment of infectious myocarditis is increasingly demanding and includes conservative methods of treating heart failure, immunomodulatory and immunospressive therapy, methods of mechanical circulatory support, and heart transplantation 3.
• Approximately 75% of patients admitted with myocarditis have an uncomplicated course, with a mortality rate of approximately 0% 2.
• Immunosuppression (eg, corticosteroids) is appropriate for patients who have myocarditis characterized by eosinophilic or giant cell myocardial infiltrations or due to systemic autoimmune disorders 2.
• First-line therapy depends on acuity, severity, clinical presentation, and etiology and includes supportive care 2.

Clinical Manifestations

• The clinical manifestations of acute myocarditis vary widely--from asymptomatic changes on electrocardiogram to fulminant heart failure, arrhythmias and sudden cardiac death 4.
• Approximately 82% to 95% of adult patients with acute myocarditis present with chest pain, while 19% to 49% present with dyspnea, and 5% to 7% with syncope 2.
• The presentation pattern of viral myocarditis can range from nonspecific symptoms of fatigue and shortness of breath to more aggressive symptoms that mimic acute coronary syndrome 5.