Multimodality Imaging and Multidisciplinary Diagnosis of Hydroxychloroquine Cardiotoxicity With CMD and Libman-Sacks Endocarditis.

backgroundHydroxychloroquine (HCQ) is used in systemic lupus erythematosus, with cardiotoxicity considered a rare but serious complication. CASE SUMMARY: A 46-year-old woman with long-standing systemic lupus erythematosus and recurrent pericarditis presented with new-onset heart failure with reduced ejection fraction. Multimodality imaging revealed coronary microvascular dysfunction (CMD) without late gadolinium enhancement or obstructive coronary disease. A small aortic valve mass, consistent with Libman-Sacks endocarditis, was also incidentally identified. Endomyocardial biopsy confirmed HCQ cardiotoxicity with curvilinear bodies and myeloid figures. After HCQ discontinuation and initiation of alternative immunosuppression, the patient's ejection fraction and symptoms improved. DISCUSSION: This case highlights an atypical presentation of HCQ cardiotoxicity manifesting as CMD and systolic dysfunction. Multimodality imaging, biopsy, and multidisciplinary care were critical for diagnosis and management, emphasizing the need for clinical vigilance in autoimmune patients on long-term HCQ therapy. TAKE-HOME MESSAGES: HCQ cardiotoxicity may present atypically with CMD and systolic heart failure, even in the absence of classic imaging features. Early recognition, multimodality imaging, biopsy confirmation, and coordinated multidisciplinary care are essential for accurate diagnosis and optimal management in patients with autoimmune disease.