Amiodarone Induced Lung Toxicity Summary



Who?

• 5% of patients

• Dose ≥ 400 mg per day



How?  Possible mechanisms:

• Direct cytotoxic lung injury

• Indirect hypersensitivity/immunologic reaction

• Amiodarone half life: 45 days in fatty tissue



Presentation?

• Acutely (hours to days after surgery or angiography)

• Chronically (months to years after starting amiodarone treatment)

• Can rarely present with eosinophilic pneumonia, organizing pneumonia, ARDS, DAH, solitary and multiple pulmonary nodules and masses, and exudative pleural effusions

• Acute toxicity (e.g., acute respiratory distress syndrome) is rare but is associated with high mortality (up to 50%).

• Chronic toxicity (e.g., chronic interstitial pneumonitis, organizing pneumonia) is more common and presents gradually with symptoms including:

    1. Non-productive cough

    2. Dyspnea

    3. Fever

    4. Pleuritic chest pain

    5. Fatigue and/or weight loss

    6. Mortality has been reported as up to 10% in some studies



Characteristic finding is accumulation of lipid-laden 'foamy' macrophages in alveolar spaces.

• Patchy or diffuse infiltrates

• Ground glass opacities

• Reticular + Nodular opacities; traction bronchiectasis

• Most commonly: Interstitial pneumonitis



Diagnosis:

• Exclude other causes like:

    - Heart failure

    - Infectious pneumonia

    - Pulmonary embolism

    - Malignancy

    - Exclusion of other ILDs

• Presence of foamy macrophages in the BAL

• Improvement in symptoms and radiographic manifestations following withdrawal of amiodarone (with or without glucocorticoid therapy)

• 20% ↓ in DLCO & new ground glass or reticular opacities on chest radiograph and confirmatory findings on HRCT is highly suggestive but not diagnostic of amiodarone-induced pulmonary toxicity.



Labs:

• Nonspecific leukocytosis

• ↑ LDH

• ↑ ESR, CRP



BAL:

• Lymphocytosis

• Neutrophilia

• Eosinophilia

• Normal BAL cellular counts

• Foamy macrophages



Treatment:

• Stopping amiodarone

• Symptomatic patients: Corticosteroids



Prognosis:

• Favorable in case of most common presentation: Interstitial pneumonitis



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