Myocarditis Following Immune Checkpoint Inhibition With Pembrolizumab: Management in a Context of Steroid Intolerance

Immune checkpoint inhibitors (ICIs) are a major advance in oncology and have become first- or second-line therapy for over 50% of oncology patients. ICI-associated myocarditis is a complication that, although rare, has a high mortality rate. We present a case of ICI-associated myocarditis presenting as complete heart block. Traditional treatment with high-dose steroids was abandoned in this case, owing to steroid-induced psychosis. Alternative treatment with immunomodulators was initiated with a good response. This case highlights the variable presentation of ICI-associated myocarditis. As use of ICIs continues to expand, an understanding of their adverse reactions and best treatments will be needed.