A case report of myocarditis secondary to eosinophilic granulomatosis with polyangiitis.

Background: Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis. Cardiac involvement is the major cause of morbidity and mortality in these patients. Early recognition and treatment initiation for such manifestations are key to improved patient outcomes.

Case Summary: We report the case of a 60-year-old man with a history of therapy-resistant asthma and rhinitis. He presented with acute chest pain, sinus tachycardia, and marked peripheral eosinophilia. Transthoracic echocardiogram (TTE) showed segmental anterior left ventricular (LV) wall motion abnormalities with impaired systolic function (LV ejection fraction 45%) and a small pericardial effusion. Invasive coronary angiography revealed unobstructed coronary arteries. Cardiac magnetic resonance imaging confirmed the TTE findings and demonstrated oedema and active inflammation of the anterior and anteroseptal LV segments [Short inversion time recovery (STIR)-T2] and an unusual pattern of non-ischaemic late gadolinium enhancement extending across multiple coronary territories. Autoantibody testing detected a positive -ANCA and myeloperoxidase (MPO) antibodies. Overall, the investigation findings supported a diagnosis of ANCA-positive EGPA with acute myocardial involvement. He was initially treated with high-dose corticosteroids, cyclophosphamide, and rituximab. The patient had a good symptomatic and biochemical (normalized troponin T and MPO titre) recovery. In addition, subsequent TTE showed improvement of LV systolic function and resolution of regional wall motion abnormalities.

Discussion: In this case, prompt diagnosis facilitated early initiation of immunosuppressive therapy and disease remission. CMR provides non-invasive assessment of myocardial tissue characterization and, used in conjunction with other tools, can be instrumental in detecting myocardial involvement in EGPA.