What is the treatment for myocarditis?

Treatment of Myocarditis

All patients with definite myocarditis should be hospitalized at an advanced heart failure center and treated with guideline-directed medical therapy for heart failure, while immunosuppression is reserved only for specific subtypes including giant cell myocarditis, cardiac sarcoidosis, eosinophilic myocarditis, or immune checkpoint inhibitor-induced disease. 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 needed 1, 2
• Transfer patients with fulminant myocarditis immediately to centers with expertise in mechanical circulatory support (ECMO, percutaneous cardiopulmonary support) 1, 3
• Fulminant myocarditis carries 28% mortality at 60 days despite aggressive treatment, though paradoxically has better long-term prognosis than non-fulminant forms if patients survive the acute phase 1, 3

Standard Medical Therapy

Initiate guideline-directed heart failure therapy before discharge:

• Start ACE inhibitors or ARBs for neurohormonal blockade in all patients with systolic blood pressure >100 mmHg (e.g., captopril 1-6.25 mg initially) 1, 3
• Use beta-blockers only if hemodynamically stable, particularly for patients with supraventricular arrhythmias; avoid in overt heart failure with pulmonary congestion or low cardiac output 1, 2, 3
• Add aldosterone antagonists for patients with mildly reduced left ventricular function and stable hemodynamics 1, 2
• Titrate all medications appropriately in the outpatient setting after discharge 1, 2

Critical Pitfall to Avoid

Avoid nonsteroidal anti-inflammatory drugs as they increase inflammation and mortality in myocarditis, despite their common use for chest pain 4

Mechanical Circulatory Support

Initiate mechanical circulatory support urgently if cardiogenic shock does not reverse rapidly with pharmacological therapy (inotropes like dopamine 5-50 mcg/kg/min) 1, 3

Options include:

• Percutaneous cardiopulmonary support 1
• ECMO 1, 3
• Intra-aortic balloon pump 1

Immunosuppression: When to Use

Immunosuppression is generally NOT indicated for acute lymphocytic myocarditis in adults based on individual trials and meta-analyses 4, 2

DO use immunosuppressive therapy in these specific circumstances:

• Giant cell myocarditis - requires immunosuppression 4, 1, 2
• Cardiac sarcoidosis - requires immunosuppression 4, 1, 2
• Eosinophilic myocarditis - requires immunosuppression 4, 1, 2
• Immune checkpoint inhibitor-induced myocarditis - permanently discontinue immunotherapy and start high-dose methylprednisolone 4, 1
• Myocarditis with COVID-19 pneumonia requiring supplemental oxygen - treat with corticosteroids 2

Key Evidence on Immunosuppression

High-dose corticosteroids resulted in better treatment response in immune checkpoint inhibitor-associated myocarditis, with lower-dose steroids associated with elevated troponin and higher rates of major adverse cardiac events 4

Arrhythmia Management

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

Activity Restriction

Mandate complete exercise abstinence and avoid competitive sport participation for 3-6 months after diagnosis 4, 1, 2

This is critical because sustained aerobic exercise during acute viral myocarditis leads to increased mortality in animal models and can cause sudden death 4

Reassess with clinical evaluation and functional testing before resuming competitive sports 4

Follow-Up Surveillance

Perform follow-up testing 3-6 months after presentation to assess recovery: 1, 2

• Repeat echocardiography or cardiac MRI to assess ventricular function 1
• Reassess cardiac biomarkers 1
• Monitor for development of dilated cardiomyopathy, which occurs in 21% of patients during long-term follow-up 1

Special Considerations for Immune Checkpoint Inhibitor Myocarditis

This is a particularly lethal form requiring aggressive management:

• Prevalence is 1.14% in patients on ICI therapy, with median onset 34 days from treatment start 4
• 64% of cases occurred after only 1-2 ICI doses 4
• 42% had concurrent severe immune-related adverse events, most commonly myositis and myasthenia gravis 4
• Troponin levels ≥1.5 ng/mL were associated with 4-fold increased risk of major adverse cardiac events (hazard ratio 4.0; 95% CI 1.5-10.9) 4
• 89% received corticosteroids, with high-dose steroids showing better treatment response 4