Myocarditis and Eosinophilia: Three Cases of Hypereosinophilic Syndrome and Myocarditis

Eosinophilic infiltration is a rare and underrecognized cause of myocarditis associated with prolonged eosinophilia. Before advanced imaging and routine biopsy, patients were diagnosed with an idiopathic cardiomyopathy with subsequent diagnosis made on autopsy. We present 3 cases of eosinophilic myocarditis diagnosed by cardiac biopsy classified as hypereosinophilic syndrome. Two patients presented with severe left ventricular dysfunction, and 1 patient presented with cardioembolic stroke. All patients were successfully treated with glucocorticoid therapy. Our cases highlight the importance of early diagnosis with endomyocardial biopsy and prompt immunosuppressive treatment.