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Myocarditis (acute)

Royal College of Physicians (RCP): acute myocarditis: aetiology, diagnosis and management

Background Information

Inflammatory disease of the myocardium, which is diagnosed definitely on endomyocardial biopsy.
 

Idiopathic in ~50% of cases

Infectious causes:
  • Viral infection (most common identifiable cause): typically Coxsackie B viruses
  • Bacterial infection: notable causes include Group A streptococcus, Corynebacterium diphtheriae (diphtheria), Borrelia burdorferi (borreliosis/Lyme disease), Mycobacterium tuberculosis
  • Fungal infection: Candida, Aspergillus
  • Parasitic infection: Toxoplasma gondii, Trypanosoma cruzi (Chagas disease)
Non-infectious causes:
  • Autoimmune: systemic lupus erythematous (SLE), Sarcoidosis, Kawasaki disease, Giant cell myocarditis
  • Drug-induced: anthracyclines (doxorubicin, daunorubicin)
  • Other: alcohol, cocaine, radiation therapy

Patient factors:
  • Young age (highest incidences in 20-40 y/o)
  • Absence of cardiovascular risk factors, e.g. hypertension, hyperlipidaemia, diabetes mellitus, smoker
  • Recent upper respiratory tract infection (URTI), or gastrointestinal (GI) illness

Clinical features:
  • Prodromal coryzal symptoms (seen up to ~80% cases)
  • Central chest pain (seen in 85-95% of cases)
  • Breathlessness
  • Palpitations

Examination findings:
  • Fever

Guidelines

If the aetiology is viral of origin or not identified, no specific treatment is required.
  • Treat underlying cause, if identified (e.g. immunosuppressive therapy for autoimmune causes and antibiotics for bacterial causes)
  • Treat any complications (i.e. heart failure, arrhythmia)
 

NSAIDs are not recommended in view of potential exacerbation of heart failure.

References

Author: Konstantinos Mantonanakis
Reviewer: 
Last Edited: 08/01/2025