Immune Checkpoint Inhibitor-Related Acute Myocarditis Masquerading as Acute Coronary Syndrome.

A 64-year-old woman presented to the local hospital with syncope. On presentation, an arterial blood gas analysis revealed profound hypoxemia necessitating intubation and mechanical ventilation. A computed tomography scan of the chest showed evidence of a thrombus in the right lower lobe pulmonary artery without evidence of right ventricular strain, with an abnormal high sensitivity troponin T at The patient was transferred to our tertiary care referral center given her complicated cardiac history which was significant for remote ischemic stroke and patent foramen ovale status postclosure complicated by peridevice right atrial thrombus. She also had a complex oncologic history of multiple malignancies secondary to Lynch Syndrome, including urothelerian carcinoma of the endometrium and pancreatic adenocarcinoma. The patient was initiated on the immune checkpoint inhibitor (ICI) pembrolizumab every 42 days, approximately 1 year prior to presentation.