Fulminant eosinophilic myocarditis treated with steroids and mechanical unloading: a case report

BACKGROUND: Eosinophilic myocarditis is a rare form of myocardial inflammatory disease. Eosinophilic infiltration of the myocardium is often the consequence of a systemic disorder but can remain unexplained in up to a third of patients. The disease course can range from mild to fulminant myocarditis and mortality remains high for fulminant cases. CASE SUMMARY: A 42-year-old male was admitted for cardiogenic shock. He presented in another hospital with fever, low blood pressure, diffuse electrocardiogram-abnormalities, and elevated troponin T (4.5 µg/L; reference <0.013 µg/L) levels. Coronary angiography was unremarkable. Mechanical circulatory support with the Impella(TM) CP device was initiated. Since fulminant myocarditis was suspected and magnetic resonance imaging was not feasible in urgency, an endomyocardial biopsy was performed. He transiently developed right ventricular failure after Impella(TM) implantation, requiring the re-institution of an inotropic agent. Biopsy showed eosinophilic myocarditis, even though there was no increase in the peripheral blood eosinophil count. Methylprednisone and Ramipril were initiated to which he responded well. No systemic disease or parasitic infection was found during further work-up. Left ventricular ejection fraction rapidly improved and was completely normalized at discharge. DISCUSSION: This case demonstrates the usefulness of myocardial biopsy in fulminant myocarditis since the only histopathology guided us towards the diagnosis of eosinophilic myocarditis. Treatment with methylprednisone and an angiotensin-converting enzyme-inhibitor resulted in rapid improvement. Awake mechanical circulatory support with the Impella(TM) device proved feasible and might have helped by unloading the left ventricle, as was reflected in an immediate decrease in troponin levels, even before methylprednisone initiation.