Acute necrotizing eosinophilic myocarditis presenting with cardiogenic shock after mRNA booster dose for COVID-19: Case report and review of literature

Eosinophilic myocarditis is a rare subtype of myocarditis characterized by myocardial eosinophilic infiltration, and it is potentially lethal if untreated. In its severest form, acute eosinophilic necrotizing myocarditis may lead to cardiac dysfunction and cardiogenic shock. Several cases have been reported after coronavirus disease 2019 (COVID-19) vaccination, but the pathophysiology is still unclear. We describe a case of acute necrotizing eosinophilic myocarditis complicated by cardiogenic shock in a 33-year-old man after booster dose of mRNA COVID-19 vaccine. The patient was diagnosed with endomyocardial biopsy, successfully treated with steroids, and discharged on Day 20 after admission in stable condition. In short term follow-up, he was asymptomatic with normal left and right ventricular ejection fraction. LEARNING OBJECTIVES: Eosinophilic myocarditis (EM) still has a high morbidity and mortality, so it is crucial to promptly diagnose it and treat as appropriate. Endomyocardial biopsy is the gold standard for the diagnosis of EM. This case highlights the diagnostic work-up, differential diagnosis of hypereosinophilia, and the management of this life-threatening condition.