What is the recommended management for a patient with myocarditis?

Management of Myocarditis

All patients with definite myocarditis—whether mild or moderate in severity—should be hospitalized, ideally at an advanced heart failure center, while those with fulminant myocarditis (cardiogenic shock, sustained ventricular arrhythmias, or advanced atrioventricular block) require management at centers with expertise in mechanical circulatory support and advanced therapies. 1

Initial Diagnostic Workup

When myocarditis is suspected, the following tests should be obtained immediately:

• ECG to identify ST-segment elevation without reciprocal depression, diffuse T-wave inversions, or QRS prolongation 1
• High-sensitivity cardiac troponin (cTn) measurement 1, 2
• Echocardiogram to assess left ventricular systolic function and identify wall motion abnormalities 1, 2
• Cardiology consultation is mandatory for patients with rising troponin and/or ECG or echocardiographic abnormalities 1

Cardiac magnetic resonance imaging (CMR) should be performed in all hemodynamically stable patients with suspected myocarditis, as it can provide definitive diagnosis and is now considered sufficient for diagnosis without requiring endomyocardial biopsy in many cases 1, 3.

Severity Stratification and Hospital Setting

The severity determines the appropriate care setting:

• Mild-to-moderate myocarditis: Hospitalization at an advanced heart failure center 1
• Fulminant myocarditis (hemodynamic compromise, cardiogenic shock, sustained ventricular arrhythmias, advanced AV block): Transfer to centers with mechanical circulatory support capabilities, including V-A ECMO 1, 2

Approximately 75% of hospitalized myocarditis patients have an uncomplicated course with near-zero mortality, while those with acute heart failure or ventricular arrhythmias face 12% in-hospital mortality or transplant rates, and hemodynamically unstable patients requiring mechanical support have 28% mortality at 60 days 2.

Medical Management

Supportive Care (All Patients)

Guideline-directed medical therapy for heart failure should be initiated when appropriate and continued after discharge 1. This includes:

• Beta-blockers may be used in hemodynamically stable patients, particularly those with supraventricular arrhythmias, though they can precipitate cardiogenic shock in severely compromised patients 1
• Aldosterone system inhibitors may be used empirically in patients with mildly reduced LV systolic function and stable hemodynamics 1

Corticosteroid Therapy (Context-Specific)

Corticosteroids should be administered to patients with myocarditis who have concurrent COVID-19 pneumonia requiring supplemental oxygen 1.

Intravenous corticosteroids may be considered in the following specific scenarios 1:

• Hemodynamic compromise with suspected or confirmed COVID-19 myocarditis
• Multisystem inflammatory syndrome in adults (MIS-A)
• Endomyocardial biopsy evidence of severe myocardial infiltrates or fulminant myocarditis (balanced against infection risk)
• Eosinophilic or giant cell myocarditis 2
• Myocarditis due to systemic autoimmune disorders 2

Pericardial Involvement

For patients with concurrent pericardial involvement, NSAIDs, colchicine, and/or prednisone are reasonable treatment options 1. NSAIDs help alleviate chest pain and inflammation, while low-dose colchicine or prednisone may be added for persistent symptoms with tapering based on clinical response 1.

Endomyocardial Biopsy Indications

While CMR can provide definitive diagnosis in many cases 3, endomyocardial biopsy remains the gold standard for histological classification and establishing underlying etiology 4. Biopsy should be considered when:

• Specific histological subtypes need confirmation (eosinophilic, giant cell) to guide immunosuppression 2
• Etiology-specific treatment is being considered 5
• Diagnosis remains uncertain despite non-invasive testing 6

Exercise Restriction

Patients with clinical myocarditis should abstain from exercise for 3-6 months 1. Return to play decisions should be based on:

1. Absence of cardiopulmonary symptoms
2. Resolution of laboratory evidence of myocardial injury (normalized troponin)
3. Normalization of LV systolic function
4. Absence of spontaneous or inducible cardiac arrhythmias on ECG monitoring and exercise stress testing 1

Reassessment for resolution of myocardial inflammation is reasonable, as CMR abnormalities may resolve in 41% of patients within a median of 8 weeks, though clinical myocarditis takes longer 1.

Follow-Up

Follow-up testing (ECG, echocardiogram, ambulatory rhythm monitor, CMR) should be performed 3-6 months after presentation, particularly in patients with ongoing cardiac symptoms or findings suggestive of significant myocardial involvement 1.

Critical Pitfalls to Avoid

• Do not use beta-blockers in patients with significantly compromised cardiac function, as they can precipitate cardiogenic shock 1
• Do not routinely use immunosuppression for viral myocarditis unless specific histological subtypes (eosinophilic, giant cell) are confirmed or there is hemodynamic compromise in specific contexts 2, 4
• Do not delay transfer to advanced centers for patients with fulminant presentations—early mechanical circulatory support improves outcomes 1, 2
• Do not allow premature return to exercise—the 3-6 month restriction is based on reducing risk of acute cardiac events, even though evidence for this specific timeframe is limited 1