II. Epidemiology

  1. Occurs in 1-2% of patients on Amiodarone per year

III. Pathophysiology

  1. Acute or subacute pneumonitis related to pulmonary drug deposition

IV. Symptoms

  1. Dyspnea
  2. Fever and cough may occur

V. Differential Diagnosis

VI. Imaging

  1. Chest XRay
    1. Diffuse Pulmonary Infiltrates
    2. In some cases may appear similar to lobar Pneumonia
  2. CT Chest
    1. Extensive bilateral alveolar and Interstitial Infiltrates
    2. Ground-glass opacities

VII. Diagnosis

  1. Clinical diagnosis only (no lab or imaging study is diagnostic)
  2. Pulmonary Function Tests
    1. Restrictive Lung Disease pattern with decreased DLCO
  3. Bronchoscopy with bronchoalveolar lavage (BAL)
    1. Evaluates for other causes of diffuse lung disease
    2. Absence of foamy Macrophages makes Amiodarone toxicity unlikely
      1. However foamy Macrophages are also seen in up to 50% of patients on Amiodarone

VIII. Precautions

  1. Often mis-diagnosed as Pneumonia or Congestive Heart Failure
  2. Consider Amiodarone toxicity in refractory Pneumonia or CHF

IX. Management

  1. Discontinue Amiodarone (best prognosis with early discontinuation)
  2. Prednisone 40-60 mg orally daily and slowly tapered over 4-12 months

X. Prognosis

  1. Most cases, if discontinued early, improve after discontinuation of Amiodarone
    1. Improvement may take months due to the Amiodarone long half-life
  2. Amiodarone Pulmonary Toxicity is fatal in some cases

XI. Prevention

  1. Obtain baseline tests before starting Amiodarone
    1. Pulmonary Function Tests
    2. Chest XRay

XII. References

  1. Weinstock, Orman, Frank and Greenwald in Herbert (2016) EM:Rap 16(1):9-11
  2. Wolkove (2009) Can Respir J 16(2): 43–8 +PMID:19399307 [PubMed]

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