Amiodarone‐Induced Pulmonary Toxicity With Confirmed Elevated Plasma Mono‐Desethyl‐Amiodarone Levels

ABSTRACT Amiodarone hydrochloride is an effective antiarrhythmic drug that can cause serious adverse effects, including amiodarone‐induced pulmonary toxicity (APT). We report a case of an 81‐year‐old man who presented with cough, sputum and progressive dyspnoea 10 months after receiving amiodarone therapy following electrical cardioversion for atrial fibrillation. Chest computed tomography (CT) revealed diffuse bilateral ground‐glass opacities. Bronchoalveolar lavage fluid demonstrated lymphocytosis with foamy macrophages, whereas infectious aetiologies were excluded. Although the cumulative amiodarone dose was relatively low (approximately 60 g), the serum mono‐desethyl‐amiodarone concentration was 0.75 μg/mL. APT was diagnosed based on the clinical, radiological and bronchoalveolar lavage findings. The patient's condition showed rapid clinical and radiological improvements after amiodarone was discontinued and corticosteroid therapy was initiated. Elevated serum concentrations of mono‐desethyl‐amiodarone are associated with an increased risk of APT. This case suggests that measuring mono‐desethyl‐amiodarone levels may facilitate APT diagnosis, even at lower cumulative doses of amiodarone.