What is the initial treatment approach for myocarditis?

Initial Treatment Approach for Myocarditis

The initial treatment approach for myocarditis should include hospitalization for patients with definite myocarditis (even mild or moderate cases), ideally at an advanced heart failure center, with implementation of guideline-directed medical therapy for heart failure and appropriate supportive care. 1

Diagnostic Evaluation

Before initiating treatment, proper diagnosis is essential:

• Initial testing should include ECG, cardiac troponin measurement (preferably high-sensitivity assay), and echocardiogram 1
• Cardiology consultation is recommended for patients with rising troponin and/or ECG or echocardiographic abnormalities concerning for myocarditis 1
• Cardiac MRI is recommended in hemodynamically stable patients with suspected myocarditis 1
• Endomyocardial biopsy should be performed in patients with unexplained acute myocarditis who require inotropic support, mechanical circulatory support, have high-grade heart block, sustained ventricular tachycardia, or fail to respond to guideline-based therapy 1

Treatment Algorithm

Step 1: Hospitalization and Supportive Care

• Hospitalize patients with definite myocarditis (even mild/moderate cases) 1
• Patients with fulminant myocarditis should be managed at centers with expertise in advanced heart failure, mechanical circulatory support, and other advanced therapies 1
• Avoid nonsteroidal anti-inflammatory drugs (NSAIDs) due to risk of increased inflammation and mortality 1

Step 2: Etiology-Specific Treatment

For COVID-19 related myocarditis:

• Patients with myocarditis and COVID-19 pneumonia requiring supplemental oxygen should receive corticosteroids 1
• For suspected pericardial involvement, treatment with colchicine and/or prednisone is reasonable 1

For immune checkpoint inhibitor (ICI) related myocarditis:

• Withhold ICI therapy 1
• Initiate high-dose corticosteroids (methylprednisolone 1000 mg/day followed by oral prednisone 1 mg/kg/day) 1
• Continue corticosteroids until resolution of symptoms and normalization of troponin, LV systolic function, and conduction abnormalities 1

For other forms of myocarditis:

• Immunosuppression is generally not indicated for acute lymphocytic myocarditis in adults 1
• For giant cell myocarditis, cardiac sarcoidosis, or eosinophilic myocarditis, treatments directed at modifying the immune response should be considered 1

Step 3: Management of Complications

• For hemodynamic instability, consider intravenous corticosteroids in suspected or confirmed COVID-19 myocarditis 1
• For steroid-refractory or high-grade myocarditis with hemodynamic instability, consider other immunosuppressive therapies such as antithymocyte globulin, infliximab (except in patients with heart failure), mycophenolate mofetil, or abatacept 1
• Mechanical circulatory support may be required for patients who develop cardiogenic shock despite optimal medical management 1
• Acute arrhythmia management is supportive, as arrhythmias often resolve with resolution of acute inflammation 1

Step 4: Long-term Management

• Initiate and continue guideline-directed medical therapy for heart failure after discharge as appropriate 1
• Avoid competitive sports for 3-6 months after diagnosis of myocarditis 1
• Reassessment with clinical evaluation and functional testing is indicated before competitive sport participation is resumed 1

Special Considerations and Pitfalls

• Severity assessment is crucial - fulminant myocarditis requires more aggressive management at specialized centers 1
• Avoid NSAIDs in acute myocarditis as they may increase inflammation and mortality 1
• Exercise restriction is important during the acute and recovery phases to prevent adverse outcomes 1
• The role of immunosuppression in patients requiring mechanical circulatory support has not been systematically investigated and remains uncertain 1
• For vaccine-associated myocarditis, diagnosis and treatment approach should be analogous to myocarditis following SARS-CoV-2 infection 1