Loeffler's endomyocarditis: from cardiac arrest to complete recovery.

Hypereosinophilic syndromes are rare diseases; however, cardiac involvement is frequently seen. When diagnosed promptly, the prognosis is relatively good; however, a final diagnosis is made by ruling out many conditions leading to secondary eosinophilia. We present a case of Loeffler's endomyocarditis primarily misdiagnosed as an acute coronary syndrome, complicated by low output heart failure and cardiac arrest. After hypereosinophilic syndrome was confirmed and treatment with prednisone initiated, the patient responded well to therapy, and her further recovery was complete and uneventful.