Key Clinical MessageBaseline assessment and interval monitoring with a careful history, clinical examination, laboratory work‐up, and noninvasive imaging modalities may be beneficial for early detection of immune checkpoint inhibitor‐associated side effects.AbstractPrevious reports of immune checkpoint inhibitors' cardiotoxic effects include pericarditis, myocarditis, myocardial infarction, ventricular dysfunction, vasculitis, and electrical abnormalities. The authors report a case of acute heart failure caused by nivolumab‐induced cardiotoxicity in a middle‐aged man with advanced esophageal carcinoma with no previous cardiac history or significant cardiovascular risk factors.