Immune Checkpoint Inhibitor Myocarditis and Myotoxicity

Immune checkpoint inhibitor (ICI)-associated myocarditis is uncommon but has been described as an important and potentially fatal complication of cancer treatment. Increasing evidence from a variety of data sources have reframed this complication as part of ICI-associated myotoxicity (ICI-M), a systemic cardiomuscular syndrome in which myocarditis, myositis, conduction disease, ventricular arrhythmias, dysphagia, pseudo-myasthenic oculobulbar signs, and respiratory muscle failure may coexist. Elevated troponin with ICI use is not synonymous with myocarditis but instead should trigger a structured evaluation that considers symptoms, ECG findings, troponin and creatine kinase concentrations, structural and functional assessments including left ventricular function, pathology when feasible, and exclusion of alternative causes including other cardiotoxic therapies. The severity of ICI-M is heterogeneous and can now be stratified using the presence of active thymoma, cardiomuscular symptoms, low QRS-voltage, left ventricular ejection fraction