What is the treatment for an adult patient with myocarditis and no underlying chronic conditions?

Treatment for Myocarditis

All patients with definite myocarditis should be hospitalized at an advanced heart failure center and treated with guideline-directed heart failure therapy, while immunosuppression should be reserved only for specific subtypes like giant cell myocarditis, cardiac sarcoidosis, or eosinophilic myocarditis. 1, 2

Immediate Hospitalization and Risk Stratification

• Hospitalize all patients with mild or moderate myocarditis at an advanced heart failure center to ensure access to mechanical circulatory support if clinical deterioration occurs 3, 1, 4
• Patients with fulminant myocarditis (cardiogenic shock, sustained ventricular arrhythmias, or advanced atrioventricular block) require immediate transfer to centers with expertise in mechanical circulatory support including V-A ECMO 3, 1, 2
• Stable patients with chest pain as the only symptom, preserved left ventricular function, and no ventricular arrhythmias can be managed in the ambulatory setting with close monitoring 2

Standard Medical Therapy

Initiate guideline-directed heart failure therapy before discharge, which forms the cornerstone of treatment for all patients with myocarditis 3, 1, 4:

• ACE inhibitors or ARBs for neurohormonal blockade in all patients with systolic blood pressure >100 mmHg 1
• Low-dose aldosterone antagonists may be used empirically in patients with mildly reduced left ventricular systolic function and stable hemodynamics 3, 1, 2
• Beta-blockers should only be used if hemodynamically stable, particularly for patients with supraventricular arrhythmias 3, 1, 2
  • Critical caveat: Beta-blockers can precipitate cardiogenic shock in patients with greater cardiac compromise and should be avoided in overt heart failure with pulmonary congestion or low cardiac output 1, 2

Anti-Inflammatory Therapy

• Nonsteroidal anti-inflammatory drugs (NSAIDs) should be avoided in isolated myocarditis due to risk of increased inflammation and mortality 3, 2
• NSAIDs may only be used for associated pericardial involvement to alleviate chest pain and inflammation 3, 2, 4
• Low-dose colchicine or prednisone may be added for persistent chest pain, with tapering based on symptoms and clinical findings 3, 2

Immunosuppression: When to Use

Immunosuppression is generally NOT indicated for acute lymphocytic myocarditis in adults based on individual trials and meta-analyses 3, 1, 4:

• Use immunosuppressive therapy only in specific circumstances: giant cell myocarditis, cardiac sarcoidosis, eosinophilic myocarditis, or immune checkpoint inhibitor-induced disease 3, 1, 2
• Empiric corticosteroids may be considered in fulminant myocarditis with hemodynamic compromise or multisystem inflammatory syndrome in adults (MIS-A), as this approach was associated with favorable prognosis in small series 3, 2
• For patients with myocarditis and COVID-19 pneumonia requiring supplemental oxygen, corticosteroids should be used 3, 4

Mechanical Circulatory Support

• Mechanical circulatory support may be required in patients who develop cardiogenic shock despite optimal medical management 3, 2, 4
• Some patients with myocarditis can be bridged to recovery with mechanical support 3, 2

Activity Restriction

Mandate complete exercise abstinence and avoid competitive sport participation for 3-6 months after diagnosis, as sustained aerobic exercise during acute viral myocarditis can lead to increased mortality and sudden death 3, 1, 2:

• Reassess with clinical evaluation and functional testing before resuming competitive sports 3, 1, 4

Arrhythmia Management

• Acute arrhythmia management is supportive, as arrhythmias often resolve with resolution of acute inflammation 3, 2, 4
• Insert temporary pacemaker if symptomatic or high-grade AV block triggers ventricular tachyarrhythmias 1
• For drug-refractory ventricular arrhythmias after myocarditis, endocardial and epicardial radiofrequency catheter ablation can be effective 3, 2

Follow-Up Surveillance

Perform follow-up testing 3-6 months after presentation to assess recovery 3, 1, 4:

• Include ECG, echocardiogram, ambulatory rhythm monitor, and cardiac MRI 3, 2, 4
• Monitor for development of dilated cardiomyopathy, which occurs in 21% of patients during long-term follow-up 1
• Particularly important in those with ongoing cardiac symptoms and/or findings suggestive of significant or worsening myocardial involvement 3

Common Pitfalls to Avoid

• Do not use NSAIDs routinely in isolated myocarditis without pericardial involvement due to increased inflammation risk 3, 2
• Do not initiate beta-blockers in hemodynamically compromised patients as they can precipitate cardiogenic shock 1, 2
• Do not use empiric immunosuppression for typical lymphocytic viral myocarditis, as it has not demonstrated benefit and increases infection risk 1, 2
• Do not allow early return to exercise before the 3-6 month restriction period and proper reassessment 3, 1, 2