Atypical Presentation of Eosinophilic Endomyocardial Disease

Idiopathic hypereosinophilic syndrome is classically defined as prolonged, unexplained peripheral eosinophilia in a patient presenting with evidence of end-organ damage. The heart is frequently involved, resulting in eosinophilic endomyocardial disease and eventually restrictive cardiomyopathy. The mortality rate is high because of progressive heart failure or ventricular arrhythmias. We describe a patient who presented with a left ventricular apical thrombus without notable peripheral eosinophilia. Findings from clinical evaluation and extensive diagnostic testing, including right ventricular biopsy, were inconclusive. Resection of the thrombus and subjacent endomyocardium revealed eosinophilic infiltration of the endomyocardium, which led to the diagnosis of eosinophilic endomyocardial disease. Clinicians should be aware of the variable presentation of patients with eosinophil-associated endomyocardial disease so that affected patients may benefit from early diagnosis and treatment.