Hydroxychloroquine-Induced Cardiomyopathy: A Case Report.

Hydroxychloroquine (HCQ) is an immunomodulatory medication used for decades. HCQ is a weak base accumulating in acidic cytoplasmic vesicles, such as lysosomes. This accumulation raises the pH and interferes with the functions of the lysosomal enzymes, including α-galactosidase A, resulting in a unique clinical and pathologic feature. We present a case with severe HCQ-induced cardiomyopathy to show the pattern of cardiac involvement and available imaging and pathologic modalities. The case involves a 76-year-old woman with a history of Sjögren's disease who had been treated with HCQ for 13 years and presented with symptoms of heart failure. An echocardiogram showed thick ventricles with reduced ejection fraction, and cardiac MRI revealed mid-wall, subepicardial, and patchy late gadolinium enhancement with a non-ischemic distribution, lack of edema and perfusion abnormality, left ventricle wall thickening, biventricular hypokinesis, bilateral atrial enlargement, and mild to moderate mitral valve and tricuspid valve regurgitation, which are compatible with HCQ-induced cardiomyopathy. An endomyocardial biopsy was performed. Light microscopy showed myocyte vacuolization. The periodic acid-Schiff stain was positive. A decrease in color intensity within the vacuoles was observed when diastase was added. Electron microscopy demonstrated inclusion bodies, described as myeloid and curvilinear bodies, confirming the diagnosis. HCQ-induced cardiomyopathy is a rare, potentially fatal side effect. Given the frequent use of this medication, it is important to consider it while evaluating patients with unexplained deterioration in cardiac function after prolonged use.