Immune Checkpoint Inhibitor-Associated Myocarditis: A Rare Presentation With Atrioventricular Block and Sinus Node Dysfunction

Immune checkpoint inhibitors (ICIs) have emerged as promising therapies, allowing for durable responses in patients with various types of cancer. With the more widespread use of immunotherapy, cases of rare but often fatal ICI-associated myocarditis have captured the attention of oncologists and cardiologists.1 Atypical presentations of this immune-mediated adverse event may delay the diagnosis and initiation of treatment, impacting patients' outcomes. We describe a case of pembrolizumabassociated myocarditis presenting with complete atrioventricular (AV) block and sinus node dysfunction in a patient with lung adenocarcinoma.