Intrinsic Differences in Immune Checkpoint Inhibitor-Induced Myocarditis: A Retrospective Analysis of Real World Data

Immune-related myocarditis is a severe and even life-threatening immune-related adverse event (irAE) which may also be underestimated due to the challenge in diagnosis. The inherent difference between individuals with immune-associated myocarditis has received little attention. Our study aimed to identify which baseline characteristics could contribute to distinguishing mild from severe ICI myocarditis. A retrospective analysis was conducted between March 2019 and June 2020 in West China Hospital, and 18 patients with immune-related myocarditis were studied. Patients were classified as having mild (n = 12) or severe myocarditis (n = 6), according to the clinical manifestations and hemodynamic complications. Factors associated with severe myocarditis were identified by comparing covariates derived from medical records in various groups. In this retrospective analysis, the median age of the 18 patients was 60 years old. Most myocarditis cases occur early and approximately after the first or second ICI infusion. The severity of myocarditis may be correlated with lactate dehydrogenase (LDH) (p = 0.04) and troponin levels (p = 0.0057). The relationship between troponin and myocarditis was further confirmed in another cohort, which included 30 patients. In addition, patients are more likely to develop multi-irAEs, and myositis was the most common second irAE. Those who experience multi-irAEs usually had significantly higher LDH (p = 0.02) and myoglobin levels (p = 0.02) than those who did not experience them. All patients were treated with steroids timely, and the mortality rate was 5.6% in our study. In this study, we explored risk factors for severe myocarditis and emphasized the importance of a multidisciplinary team in assisting diagnosis and treatment options. It is critical to initiate corticosteroid therapy, regardless of the severity of the myocarditis.