Utility of cardiac magnetic resonance imaging in diagnosing eosinophilic myocarditis in a patient recently recovered from COVID-19: a grand round case report

Background Eosinophilic myocarditis (EM) secondary to eosinophilic granulomatosis with polyangiitis (EGPA) is a rare disease, for which cardiac magnetic resonance imaging (CMRI) is a useful non-invasive modality for diagnosis. We present a case of EM in a patient who recently recovered from COVID-19 and discuss the role of CMRI and endomyocardial biopsy (EMB) to differentiate between COVID-19-associated myocarditis and EM.Case summary A 20-year-old Hispanic male with a history of sinusitis and asthma, and who recently recovered from COVID-19, presented to the emergency room with pleuritic chest pain, dyspnoea on exertion, and cough. His presentation labs were pertinent for leucocytosis, eosinophilia, elevated troponin, and elevated erythrocyte sedimentation rate and C-reactive protein. The electrocardiogram showed sinus tachycardia. Echocardiogram showed an ejection fraction of 40%. The patient was admitted, and on day 2 of admission, he underwent CMRI which showed findings of EM and mural thrombi. On hospital day 3, the patient underwent right heart catheterization and EMB which confirmed EM. The patient was treated with steroids and mepolizumab. He was discharged on hospital day 7 and continued outpatient heart failure treatment.Discussion This is a unique case of EM and heart failure with reduced ejection fraction as a presentation of EGPA, in a patient who recently recovered from COVID-19. In this case, CMRI and EMB were critical to identify the cause of myocarditis and helped in the optimal management of this patient.