Hydroxychloroquine Cardiotoxicity Confirmed by Electron Microscopy: The Myocarditis Mimic
Abstract
Background: Hydroxychloroquine (HCQ) is widely used for autoimmune disease, but rare cardiotoxicity can mimic inflammatory cardiomyopathy.
Case summary: A 79-year-old woman on 10 years of HCQ presented with fatigue, dizziness, and exertional dyspnea and was found to have low cardiac output (1.75 L/min) and cardiac index (1.01 L/min/m2) physiology. Cardiac magnetic resonance imaging showed diffuse, patchy midmyocardial and subepicardial late gadolinium enhancement, whereas cardiac positron emission tomography demonstrated diffuse fluorodeoxyglucose uptake sparing the subendocardium, raising concern for myocarditis. Endomyocardial biopsy revealed cardiomyocyte vacuolization, and electron microscopy demonstrated membranous whorls and curvilinear inclusion bodies consistent with HCQ-induced lysosomal dysfunction. HCQ was discontinued with symptomatic improvement at 1 month.
Discussion: HCQ cardiotoxicity may resemble myocarditis on imaging. Biopsy with electron microscopy confirms the diagnosis and guides management.
Take-home messages: Maintain suspicion for HCQ toxicity despite inflammatory imaging patterns. Early tissue diagnosis and drug discontinuation may prevent progression and support recovery.
How strong is the evidence?
Evidence Hub reads this as a case report, done in people. Its evidence level is 5 of 5 (Very low · case / narrative / animal / in vitro / in silico). Case reports, narrative reviews, and animal, cell or computer-model studies give the weakest evidence for human health.
Read the paper
Related studies
- Strategy for Mitigating DKA Risk in Patients with Type 1 Diabetes on Adjunctive Treatment with SGLT Inhibitors: A STICH Protocol
- Glucoraphanin: a broccoli sprout extract that ameliorates obesity-induced inflammation and insulin resistance
- SGLT2 Inhibitors in Heart Failure: Targeted Metabolomics and Energetic Metabolism
- Mechanisms of blood pressure reduction with sodium-glucose co-transporter 2 (SGLT2) inhibitors
- Sodium-glucose cotransporter inhibitors: beyond glycaemic control
- Decoding the effects of SGLT2 inhibitors on cardiac arrhythmias in heart failure
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.