Immune checkpoint inhibitors are effective tumor treatment agents with survival benefits.However,immune toxicity to various organs has become a new challenge in clinical practice.The cardiac involvement can be presented as heart failure,arrhythmia(atrial fibrillation,atrioventricular block,bundle branch block,ventricular tachycardia,etc.),myocardial-pericarditis,myocardiopathy,and sudden cardiac death,etc.This patient developed abnormally increased myocardial enzymes,impaired cardiac function,and atrioventricular block after 1-month treatment with tislelizumab.Endomyocardial biopsy examination confirmed the diagnosis of immune checkpoint inhibitor-associated myocarditis.Through the diagnosis,treatment,and review of relevant literatures of this case,we wish to improve the understanding of immune checkpoint inhibitor-associated myocarditis,and therefore improve the diagnosis and treatment of immune checkpoint inhibitor-associated myocarditis for clinicians.

Immune checkpoint inhibitors are effective tumor treatment agents with survival benefits.However,immune toxicity to various organs has become a new challenge in clinical practice.The cardiac involvement can be presented as heart failure,arrhythmia(atrial fibrillation,atrioventricular block,bundle branch block,ventricular tachycardia,etc.),myocardial-pericarditis,myocardiopathy,and sudden cardiac death,etc.This patient developed abnormally increased myocardial enzymes,impaired cardiac function,and atrioventricular block after 1-month treatment with tislelizumab.Endomyocardial biopsy examination confirmed the diagnosis of immune checkpoint inhibitor-associated myocarditis.Through the diagnosis,treatment,and review of relevant literatures of this case,we wish to improve the understanding of immune checkpoint inhibitor-associated myocarditis,and therefore improve the diagnosis and treatment of immune checkpoint inhibitor-associated myocarditis for clinicians.