Probable idiopathic hypereosinophilic syndrome: A case report of severe multi-organ eosinophilic involvement in a young male presenting with heart failure.

Hypereosinophilic syndrome (HES) is a disorder characterized by elevated levels of eosinophils, which may be associated with multi-organ involvement depending on severity. The recent diagnostic criteria for idiopathic HES require an elevated absolute eosinophil count (AEC) above 1500 cells/mcL with evidence of tissue damage. We present a case of a 37-year-old male firefighter with a purported history of eosinophilic bronchitis who was referred to the hospital with syncopal episodes and a persistent productive cough. The patient showed an AEC of 4500 cells/mcL on admission associated with high inflammatory markers. Cardiac imaging demonstrated acute myocarditis with heart failure and a reduced ejection fraction. Chest imaging was initially suggestive of community-acquired pneumonia. Workup was negative for a malignant etiology; infectious causes similarly were excluded. After a multidisciplinary evaluation, a diagnosis of idiopathic HES was made and steroids were instituted with rapid resolution of symptoms. Our case illustrates the importance of considering hypereosinophilia as a precipitating factor for acute heart failure in an otherwise healthy adult. An expeditious diagnosis can lead to early initiation of steroids to avoid progression toward multi-organ failure.