Hypereosinophilic Syndrome Complicated by Eosinophilic Myocarditis With Dramatic Response to Steroid.

Eosinophilic myocarditis is an infiltrative disease that affects the myocardium leading to various presentations. It can be precipitated by medications, helminthiasis, or hypereosinophilic syndrome. We present the case of a young, male patient who presented with palpitations and dyspnea and was found to have heart failure with reduced ejection fracture of 12%. His past medical history was significant for recent lung problem treated with steroids. Based on his history and laboratory findings, he was started on intravenous steroids for treatment of eosinophilic myocarditis. Within 3 days, his ejection fracture improved to 35%. Given the nonspecific clinical presentations, mimicking other diseases, high index of suspicion is warranted to diagnose eosinophilic myocarditis. This is crucial as early detection and treatment with steroids can lead to a dramatic response.