Multimodal Imaging in the Diagnosis of Late-Stage Loeffler Endocarditis

Background: Loeffler endocarditis (LE) is a rare and progressive form of eosinophilic myocarditis characterized by endomyocardial fibrosis, mural thrombus, and restrictive cardiomyopathy. Case Summary: A 70-year-old woman presented with heart failure with preserved ejection fraction and eosinophilia. Transthoracic echocardiography and computed tomography revealed subendocardial calcifications. Cardiac magnetic resonance imaging confirmed subendocardial fibrosis and mural thrombus, consistent with fibrotic-stage LE. Stool testing identified parasitic infection as the cause of eosinophilia. Antimicrobial therapy normalized eosinophil level, but cardiac fibrosis persisted on follow-up. Discussion: LE is a rare cause of heart failure with preserved ejection fraction, with irreversible cardiac remodeling in its late stages. This case emphasizes the importance of multimodality imaging in diagnosing LE and the potential to reverse systemic—but not always cardiac—manifestations with appropriate treatment. Take-Home Message: This case highlights the features of late-stage LE and the importance of early recognition and treatment of potentially reversible causes.