Abstract
Hypereosinophilic syndrome is a rare systemic condition characterized by eosinophil-mediated organ damage. Cardiac involvement is common and typically occurs in sequential stages. We present two cases that demonstrate these different stages and presentations of eosinophilia-mediated myocardial disease, where multimodality imaging was essential for the diagnosis. More importantly, they demonstrate, for the first time, the dissociation between the eosinophil count and patients' clinical evolution, suggesting the need for close follow up even after the eosinophilia has been controlled. LEARNING OBJECTIVE: Cardiac involvement in hypereosinophilic syndrome typically occurs in three stages - necrotic, thrombotic, and fibrotic. Although cardiac damage is mediated by eosinophils, the blood eosinophil count and patients' clinical evolution are dissociated. Therefore, eosinophil count on its own is not an adequate marker of clinical evolution, and cardiac follow up should be continued even after the eosinophilia has been controlled.