Acute Myocarditis Following Zoledronic Acid Infusion: Cardiac MRI Diagnosis of a Rare Cardiotoxic Event with Contextual Literature Review.

Background and Clinical Significance: Zoledronic acid (ZA) is a widely used bisphosphonate for the prevention of skeletal-related events in patients with metastatic bone disease. While it is generally well tolerated, rare immune-mediated complications may be underrecognized. To date, myocarditis has not been reported in association with ZA. Case Presentation: A 35-year-old woman with metastatic pheochromocytoma developed acute, non-exertional chest pain approximately 36 h after receiving her first intravenous ZA infusion. Laboratory testing revealed elevated high-sensitivity troponin T, peaking at 1182 ng/L. Cardiac magnetic resonance imaging (CMR) demonstrated myocardial edema and subepicardial late gadolinium enhancement, consistent with acute myocarditis per the 2018 revised Lake Louise criteria. An extensive diagnostic workup excluded infectious, autoimmune, and ischemic causes. Symptoms and troponin levels improved following ZA discontinuation and supportive care. In the absence of alternative etiologies, and given the close temporal association with ZA administration, the diagnosis of presumed ZA-associated myocarditis was supported by clinical presentation, biochemical markers, and CMR findings, recognizing that histopathological confirmation is rarely pursued in clinically stable patients. Conclusions: To our knowledge, this is the first reported case of presumed zoledronic acid-associated myocarditis confirmed by cardiac MRI. This report highlights the diagnostic utility of CMR in suspected drug-related cardiac inflammation and the importance of considering myocarditis in patients presenting with unexplained chest pain following ZA infusion, particularly when other causes have been excluded.