Treatment of Myocarditis
The treatment of myocarditis should primarily consist of guideline-directed heart failure therapy, complete physical rest for 3-6 months, and avoidance of NSAIDs, with immunosuppression reserved only for specific subtypes such as giant cell, cardiac sarcoidosis, or eosinophilic myocarditis. 1, 2
Diagnostic Approach
Before initiating treatment, proper diagnosis is essential:
Initial testing should include:
- ECG
- High-sensitivity cardiac troponin
- Transthoracic echocardiogram
- Cardiac MRI (in hemodynamically stable patients) 1
Endomyocardial biopsy (EMB) indications:
- Patients requiring inotropic support or mechanical circulatory support
- Patients with Mobitz type 2 second-degree or higher heart block
- Sustained or symptomatic ventricular tachycardia
- Failure to respond to guideline-based therapy 1
Treatment Algorithm
1. Acute Management Based on Severity
Mild to Moderate Myocarditis:
- Hospitalization at an advanced heart failure center 1
- Supportive care with cardiac monitoring
- Guideline-directed heart failure medications:
- Beta-blockers for hemodynamically stable patients
- ACE inhibitors/ARBs for reduced ejection fraction
- Low-dose aldosterone antagonists for mildly reduced LV function 2
Fulminant/Severe Myocarditis:
- Management at centers with expertise in advanced heart failure
- Consider mechanical circulatory support (including V-A ECMO) for cardiogenic shock 1, 2
- Inotropic support as appropriate for hemodynamic instability 3
2. Specific Treatments Based on Etiology
Viral Myocarditis:
- Generally supportive care only
- Individual trials and meta-analyses suggest immunosuppression is NOT indicated for acute lymphocytic myocarditis in adults 1
COVID-19 Related Myocarditis:
- Corticosteroids for patients with concurrent COVID-19 pneumonia requiring oxygen 1, 2
- Intravenous corticosteroids may be considered for hemodynamic compromise or MIS-A 1
Immune-Related Myocarditis (IR-myocarditis):
- Interrupt immune checkpoint inhibitor therapy
- Intravenous methylprednisolone 500-1000mg daily for 3 days
- If troponin falls to <50% of peak level after 3 days, convert to oral prednisolone 1mg/kg/day (max 80mg/day), reducing by 10mg/week 1
Special Subtypes:
- For giant cell myocarditis, cardiac sarcoidosis, or eosinophilic myocarditis: immunosuppressive therapy is indicated 1, 2
3. Medications to Avoid
- NSAIDs should be strictly avoided due to risk of increased inflammation and mortality 1, 2
- Exception: For patients with suspected pericardial involvement, NSAIDs, colchicine, and/or prednisone may be reasonable 1
Follow-up and Recovery
Exercise Restriction:
Surveillance Testing (3-6 months after presentation):
- ECG
- Echocardiogram
- Ambulatory rhythm monitor
- Cardiac MRI 2
Return to Activity Criteria:
- Absence of cardiopulmonary symptoms
- Resolution of laboratory evidence of myocardial injury
- Normalization of LV systolic function
- Absence of spontaneous/inducible cardiac arrhythmias on ECG monitoring and exercise stress testing 1
Prognosis and Complications
- Approximately 75% of patients admitted with myocarditis have an uncomplicated course with mortality rate of approximately 0% 3
- Acute myocarditis complicated by heart failure or ventricular arrhythmias is associated with a 12% rate of in-hospital mortality or need for heart transplant 3
- Patients with hemodynamic instability have approximately 28% rate of mortality or heart transplant at 60 days 3
Common Pitfalls to Avoid
- Inappropriate use of NSAIDs worsening inflammation and increasing mortality 1, 2
- Premature return to strenuous activity leading to sudden death 2
- Indiscriminate use of immunosuppression for viral myocarditis 1, 2
- Overuse of beta-blockers in patients with compromised cardiac function potentially precipitating cardiogenic shock 2