Immune-related adverse event-myocarditis with marked ST-segment elevation requiring differentiation from COVID-19-induced myocarditis: a case report

Abstract

Immunotherapy with immune checkpoint inhibitors (ICIs) enhance the host immune reaction against tumour cells by inhibiting intrinsic down-regulators of the T cell-mediated immune response. Although the advent of ICIs has dramatically changed oncology, ICIs may also trigger an overactivation of T cells against non-cancerous tissues, leading to off-target immune-related adverse events (irAEs). A 64-year-old man with a history of seven courses of atezolizumab, an ICI, for small-cell lung cancer and Coronavirus disease 2019 (COVID-19) as admitted to the hospital complaining of acute chest pain. Transthoracic echocardiography showed preserved ejection fraction (EF), but electrocardiography indicated precordial ST elevations and marked increases in biomarkers for myocardial injury were observed. Emergent cardiac catheterization showed no significant coronary stenosis. On the fifth hospital day, EF decreased to 25% and pericardial effusion occurred. Endomyocardial biopsy was immediately performed, and prednisolone (60 mg/day) was administered. Troponin I level rapidly reduced, ST change and EF improved. Histological examinations demonstrated CD8-predominant T lymphocytic infiltration with myocardial cell injury, consistent with irAE-myocarditis. In irAEs, myocarditis is the most common and severe cardiac manifestation with a high mortality. Even at 20 weeks after the initial ICI treatment, irAE-myocarditis occurs and the clinical presentation may mimic ST elevation myocardial infarction. The histopathological findings suggested the high possibility of irAE-myocarditis rather than COVID-19-induced myocarditis, but COVID-19 has possibly played a role in the development of late-onset irAE-myocarditis. This educational case implies the importance of immediate recognition of irAE even after stable ICI treatment.