Idiopathic eosinophilic myocarditis presenting with features of an acute coronary syndrome

SUMMARY: A 62-year-old female was admitted with severe left-sided chest pain, nausea and pre-syncope. She had widespread T wave inversion on ECG and elevated troponins and was suspected to have an acute coronary syndrome event. Invasive coronary angiogram revealed normal coronary anatomy with no flow-limiting lesions. Echocardiography and cardiac MRI revealed impaired left ventricular (LV) systolic impairment, a mobile LV apical thrombus and a moderate global pericardial effusion with no significant compromise. Full blood count analysis indicated the patient to have significant eosinophilia, and the patient was diagnosed with idiopathic eosinophilic myocarditis. She was commenced on Prednisolone and Apixaban, and eosinophil levels returned to normal after 10 days of steroids. Over the course of 3 months, the patient had a complete recovery of her LV function and resolution of the LV thrombus. This case highlights a rare, reversible case of idiopathic eosinophilic myocarditis which may present similar to acute coronary syndrome. LEARNING POINTS: Eosinophilic myocarditis (EM) is a rare disease that can exhibit symptoms similar to acute coronary syndrome events. The diagnosis of EM should be considered in patients with chest pain, normal coronary angiogram and pronounced eosinophilia levels. Endomyocardial biopsy is the gold standard diagnostic tool; however, it has a low sensitivity detection rate and its use is not indicated in some patients. Echocardiography is useful in the initial detection of cardiac involvement and complications. However, echocardiography lacks diagnostic specificity for all forms of myocarditis including EM. Cardiac magnetic resonance is a useful method and may add in diagnosing all forms of myocarditis including EM. Patients with EM should be identified promptly and treated with high doses of oral glucocorticoid to reduce the risk of permanent cardiac dysfunction.