Myocarditis

 

• Background

  Inflammation of the myocardium.

  Causes

  50% are idiopathic. The remainder are due to:

  • Viruses: commonest diagnosed cause. Can be almost any virus, but the commonest are Coxsackie, parvovirus B19, hepatitis C, HIV, and adenovirus.
  • Bacteria: diphtheria, TB, streptococci, spirochetes (leptospirosis, syphilis, Lyme).
  • Protozoa: Chagas (Trypanosoma cruzi).
  • Drugs: mechanism can be hypersensitivity (e.g. acetazolamide, amitriptyline) or toxic (e.g. cyclophosphamide, alcohol, lithium).
  • Immune-mediated: SLE, sarcoidosis, systemic sclerosis, giant-cell myocarditis, hypereosinophilic syndrome, vasculitis.

• Signs and symptoms

  Varies from asymptomatic (ECG changes only) all the way to acute HF or sudden cardiac death. Symptoms include:

  • Fatigue
  • SOB
  • Chest pain
  • Fever
  • Palpitations
  • ↑HR, S4 gallop rhythm, soft S1.

• Investigations

  ECG:

  • ST elevation or depression.
  • T wave inversion.
  • Atrial arrhythmia
  • AV block.

  Bloods:

  • ↑ESR/CRP/WBC
  • ↑Troponin

  CXR may show HF.

• Management

  • Supportive care, treat cause.
  • Treat any HF as usual.

• Complications

  • Dilated cardiomyopathy and HF.
  • Sudden cardiac death.