Immune Checkpoint Inhibitor–Associated Myocarditis: Current Understanding of Clinical Presentation and Management

Immune checkpoint inhibitors (ICIs) have transformed the treatment landscape of multiple malignancies but are increasingly associated with immune-related cardiovascular toxicities. Among these, ICI-associated myocarditis is rare yet represents the most severe and life-threatening cardiac adverse event, characterized by early onset, malignant arrhythmias, conduction disturbances, acute heart failure, and high mortality. As ICIs are increasingly administered across earlier disease stages, prolonged durations, and combination regimens, the clinical burden of myocarditis is expected to rise. Pathogenesis is driven by dysregulated T-cell-mediated immune activation, loss of peripheral tolerance, and shared tumor-cardiac antigens, with heightened risk observed in patients receiving dual immune checkpoint blockade. Diagnosis remains challenging due to nonspecific symptoms, frequent preservation of left ventricular function, and limited sensitivity of early cardiac imaging, necessitating a multimodal approach integrating cardiac biomarkers, electrocardiography, advanced imaging, and selective endomyocardial biopsy. Early recognition and prompt initiation of high-dose corticosteroids are central to management and are associated with improved outcomes, while steroid-refractory cases may require targeted immunomodulatory therapies. Decisions regarding ICI rechallenge remain complex and must balance oncologic benefit against the risk of recurrent cardiac injury. Optimal care in this high-risk population.