What is the role of steroids, such as prednisone, in the treatment of post-viral myocarditis?

Steroids in Post-Viral Myocarditis

Corticosteroids are generally not recommended for routine treatment of post-viral myocarditis in adults, as they do not reduce mortality and may reactivate viral infections, leading to ongoing inflammation. 1, 2

General Approach to Viral Myocarditis

The American Heart Association explicitly states that immunosuppression is not indicated for the management of acute lymphocytic myocarditis in adults, based on individual trials and meta-analysis data. 1, 2, 3 The European Society of Cardiology reinforces this position, stating that corticosteroid therapy is not recommended in viral pericarditis (Class III, Level C), as steroids are known to reactivate many viral infections and lead to ongoing inflammation. 1

Why Steroids Are Contraindicated

• Viral reactivation risk: Corticosteroids can reactivate viral infections, perpetuating the inflammatory cascade rather than resolving it. 1
• Lack of mortality benefit: A Cochrane systematic review of 8 RCTs with 719 participants found no significant reduction in mortality with corticosteroid use (RR 0.93,95% CI 0.70-1.24). 4, 5
• Increased inflammation: NSAIDs and corticosteroids may increase inflammation and mortality in isolated myocarditis without pericardial involvement. 1, 2

Specific Exceptions Where Steroids May Be Considered

1. Giant Cell Myocarditis, Cardiac Sarcoidosis, or Eosinophilic Myocarditis

Immunosuppression should be considered in these specific non-viral forms of myocarditis. 1, 2, 3, 6 These conditions have distinct pathophysiology involving autoimmune or hypersensitivity mechanisms rather than direct viral injury.

2. Fulminant Myocarditis with Severe Inflammatory Infiltrates

Empiric corticosteroids may be considered in fulminant myocarditis with biopsy evidence of severe myocardial inflammatory infiltrates or in patients with hemodynamic compromise. 2, 3 This represents a clinical judgment in life-threatening situations where the potential benefit may outweigh the risk of viral reactivation.

3. Immune Checkpoint Inhibitor-Associated Myocarditis

For suspected or confirmed ICI-associated myocarditis, high-dose corticosteroids (methylprednisolone 1000 mg/day followed by oral prednisone 1 mg/kg/day) should be initiated promptly and continued until resolution of symptoms and normalization of troponin, LV systolic function, and conduction abnormalities. 1 This is a distinct entity from viral myocarditis with different pathophysiology.

4. Myocarditis with Associated Pericardial Involvement

When pericardial involvement is present, low-dose prednisone may be added for persistent chest pain, with tapering based on symptoms and clinical findings. 2 However, NSAIDs are preferred first-line for pericardial inflammation. 2

5. COVID-19 Myocarditis with Pneumonia

Patients with myocarditis and COVID-19 pneumonia requiring supplemental oxygen should be treated with corticosteroids. 3 This recommendation is based on the proven benefit of steroids in COVID-19 pneumonia rather than the myocarditis itself.

Evidence Quality and Limitations

The Cochrane review found that while corticosteroids may improve left ventricular ejection fraction at 1-3 months (MD 7.36%, 95% CI 4.94-9.79), this finding had substantial heterogeneity and was based on small, low-quality trials. 4, 5 Only 38% of participants had viral detection performed, and among those, only 56% had positive results, limiting the applicability to confirmed viral myocarditis. 4

Recommended Treatment Approach for Viral Myocarditis

Instead of steroids, focus on:

• Guideline-directed medical therapy for heart failure (ACE inhibitors/ARBs, beta-blockers if hemodynamically stable, aldosterone antagonists). 1, 2, 3
• Supportive care with hemodynamic monitoring and arrhythmia management. 1, 2
• Activity restriction for 3-6 months, as sustained aerobic exercise during acute viral myocarditis can lead to increased mortality and sudden death. 1, 2, 3
• Mechanical circulatory support if cardiogenic shock develops despite optimal medical management. 1, 2, 3

Common Pitfalls to Avoid

• Do not use empiric immunosuppression for typical lymphocytic viral myocarditis, as it has not demonstrated benefit and increases infection risk. 2
• Do not use NSAIDs routinely in isolated myocarditis without pericardial involvement due to increased inflammation risk. 1, 2
• Do not assume all myocarditis is viral—obtain endomyocardial biopsy in severe cases to identify giant cell, eosinophilic, or sarcoid myocarditis, which require immunosuppression. 1, 2, 3
• Avoid steroids in systolic heart failure whenever possible, as long-term high-dose steroids are associated with significantly higher mortality and fluid retention. 7