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Difficulty: MediumCardiovascular System

A 68-year-old man comes to the clinic due to a 6-week history of progressively worsening shortness of breath and a dry, nonproductive cough. He has a history of hypertension, type 2 diabetes mellitus, and symptomatic paroxysmal atrial fibrillation. His medications include amiodarone, metoprolol, apixaban, and lisinopril. The patient has never smoked. His temperature is 37.1°C (98.8°F), blood pressure is 128/82 mm Hg, pulse is 68/min, and respirations are 22/min. Pulse oximetry shows 91% on room air. Physical examination reveals fine, bilateral inspiratory crackles at the lung bases. Cardiac examination shows a regular rate and rhythm with normal S1 and S2; there are no murmurs or gallops. Jugular venous pressure is 6 cm H2OH_2O. There is no lower extremity edema. Laboratory studies show a normal leukocyte count and a brain natriuretic peptide (BNP) level of 65 pg/mL. Thyroid-stimulating hormone (TSH) is 5.8 μ\mu U/mL (normal: 0.4-4.0 μ\mu U/mL) and free T4 is 1.1 ng/dL (normal: 0.9-1.7 ng/dL). Chest radiography demonstrates diffuse, bilateral interstitial opacities. Electrocardiography shows normal sinus rhythm. Which of the following is the most appropriate next step in management?

  1. Discontinuation of amiodaroneAnswer
  2. B
    Administration of intravenous furosemide
  3. C
    Administration of intravenous ceftriaxone and azithromycin
  4. D
    Administration of inhaled albuterol and ipratropium
  5. E
    Initiation of oral levothyroxine

Answer

Discontinuation of amiodarone
The correct answer identifies that the patient is suffering from amiodarone-induced pulmonary toxicity. Amiodarone is a highly effective antiarrhythmic agent but carries significant long-term side effects, the most dangerous being interstitial pneumonitis. It typically presents subacutely with progressive dyspnea on exertion, a dry nonproductive cough, and fine inspiratory crackles. Chest imaging characteristically reveals bilateral interstitial or alveolar infiltrates. When this toxicity is suspected, the most critical next step is the immediate discontinuation of amiodarone. For severe cases with hypoxemia, systemic corticosteroids are often added after infectious etiologies have been ruled out.

Step-by-Step Solution

1
Analyze the patient's presenting symptoms and medication list.
The patient presents with subacute progressive dyspnea, dry cough, and hypoxia, and is taking amiodarone for atrial fibrillation.
Identifying potential adverse effects of chronic medications is crucial in evaluating new-onset cardiopulmonary symptoms.
2
Evaluate the physical examination and objective diagnostic data.
Examination shows bilateral fine crackles without signs of volume overload (normal JVP, no edema). BNP is normal, ruling out heart failure. White blood cell count and temperature are normal, making infection unlikely. Chest X-ray shows interstitial opacities.
This effectively rules out acute decompensated heart failure and infectious pneumonia, pointing toward an intrinsic pulmonary pathology.
3
Synthesize the findings to establish the most likely diagnosis and determine the next best step.
The clinical picture perfectly aligns with amiodarone-induced interstitial pneumonitis. The immediate required action is cessation of the drug.
Amiodarone pulmonary toxicity is potentially fatal if unrecognized. Stopping the medication halts ongoing direct cytotoxicity and immune-mediated lung injury.

Key Concept

Amiodarone is a class III antiarrhythmic that can cause severe adverse effects, notably pulmonary toxicity (interstitial pneumonitis), which presents with progressive dyspnea, nonproductive cough, and interstitial opacities. The initial and most essential step in management is discontinuing the drug.
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Topics

Cardiovascular System

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