Myocarditis

Background

  • Acute inflammatory condition affecting the myocardium
    • Can be infectious, toxic or autoimmune
      • Commonly Coxsackie, Influenza A and B
        • May occur several weeks after initial symptoms
      • Can be associated with Lyme’s disease
      • Drugs that can cause it include
        • Cocaine, lithium, doxorubicin (direct injury)
        • Penicillins/sulphonamides, lead and carbon monoxide (toxic/systemic reaction)
      • Autoimmune conditions include SLE and RA
    • Risk increased in immunosupressed patients (including steroid-use and radiation); previous myocardial damage and exercise
  • Infectious type more common in otherwise healthy younger individuals and can be a cause of unexpected death in this group

Presentation

  • Fulminant myocarditis often follows a viral prodrome (fever, lethargy, myalgia, headache etc) and results in severe heart failure or cardiogenic shock (i.e. fatigue/shortness of breath worse on exertion; chest pain; palpitations; collapse)
  • Acute myocarditis presents over a longer time period with features of heart failure (can lead to cardiomyopathy)
  • Chronic myocarditides (active and persistent) are rare but may cause chest pain/palpitations without LVD.

Investigation

  • ECG changes common but non-specific
    • T wave inversions and ST changes (elevation or depression)
    • Arrhythmias (more characterisitically ventricular)
    • There may also be signs of pericarditis (myopericarditis)
  • Troponins may be raised early on
  • Echo may show LV dysfunction
  • Cardiac MRI can reveal areas of cardiac inflammation or infiltration and is usually diagnostic, although endomyocardial biopsy can be used to confirm the diagnosis (rare)

Management

  • Most cases self-limiting
  • Avoid over-exertion (risk of arrhythmia)
  • If the patient has a history of GCA, steroids may be useful
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