Myocarditis

Background

  • Inflammatory (dilated) cardiomyopathy caused by necrosis of myocytes

Causes

Phases

  • Acute
    • Viral cytotoxicity and focal necrosis
  • Subacute
    • Host's humoral/immune response leading to further cell injury
  • Chronic
    • Diffuse myocardial fibrosis and cardiac dysfunction

Clinical Features

  • Typically young patients (20 - 50 years) with few risk factors for CAD
  • Chest pain
  • Pericardial friction rub
  • Flu like syndrome
    • Fever, fatigue, myalgia, nausea and vomiting
    • Tachycardia (out of proportion to fever)
    • Tachypnea
  • New onset congestive heart failure
  • Pediatric patients:
    • Grunting
    • Retractions
    • Ronchi
  • Infants may have fulminant syndrome
    • Fever
    • Cyanosis
    • Respiratory distress
    • Tachycardia
    • Heart failure
    • Ventricular dysrhythmias
  • Consider this diagnosis in the septic-appearing patient who gets WORSE after receiving IV fluids

Differential Diagnosis

Consider other causes of CHF

Chest pain

Critical

Emergent

Nonemergent

Evaluation

  • ECG
    • Sinus tachycardia
    • Low voltages
    • Prolonged QTc
    • AV block
    • ST elevations (Usually >1 vessel distribution)
  • Elevated troponin
  • Echocardiogram
    • Decreased LVEF
    • Global hypokinesis
    • Regional wall motion abnormalities
  • Contrast MR
  • Nuclear Study
    • Widespread uptake indicating myocyte necrosis
  • Viral titres
  • Endocardial biopsy: Gold standard, but rarely used

Management

  • Acute phase
    • Antiviral agents (Pleconaril/Ribavirin) may be effective
  • Subacute phase
    • Studies have not shown efficacy of immunosupressants
    • Pediatric patients may receive high-dose IVIG
  • Chronic phase
    • Treatment for CHF symptoms
    • Ventricular Assist Devices (VAD)
    • Cardiac transplant

Disposition

  • If CHF is present, admit to monitored bed
  • If hemodynamically unstable, admit to ICU

Prognosis

  • Fulminant myocarditis has best prognosis
  • Mortality: 20% 1 yr/ 50% 5 yr
  • Children with 70% survival rate at 5 yrs

Complications

  • Ventricular dysrhythmias
  • LV anneurysm
  • CHF

See Also

References