Prognosis of immune checkpoint inhibitor-related myocarditis: Retrospective experience of a single institution.

Background: Myocarditis related to immune checkpoint inhibitors (ICIs) treatment is a rare but potentially life-threatening adverse event. To gain insight into this condition, we analyzed the clinical characteristics and prognosis of patients with ICI-related myocarditis.

Methods: Data on the clinical characteristics, management, and outcomes of patients diagnosed with ICI-related myocarditis between August 2018 and August 2023 in our institution were gathered retrospectively from medical records. Outcomes included the occurrence of major adverse cardiac events (MACE).

Results: Among 8875 patients who received ICI therapy, 31 patients experienced ICI-related myocarditis. These 31 patients had a mean age of 62 ± 12 years and included 24 (77.4 %) males and 19 patients (61.3 %) with at least one risk factor for cardiovascular disease. The median duration from ICI initiation to the onset of myocarditis symptoms was 6.3 weeks (interquartile range, 4.3-8.1 weeks). Twenty-one patients (67.7 %) developed grade 3-4 myocarditis. Thirteen patients (42 %) experienced MACE after myocarditis onset, and 15 patients (48.4 %) showed a troponin rise > 4 times the maximum limit of the standard range. On receiver operating characteristic curve analysis, troponin level could predict MACE in patients with ICI-related myocarditis with an area under the curve of 0.82 (95 % confidence interval [CI]: 0.66-0.98, p = 0.003). From Kaplan-Meier analysis, the occurrence of MACE (p = 0.002) was an independent influencing factor on patients' overall survival.

Conclusions: ICI-related myocarditis frequently leads to MACE, which is associated with poor prognosis. Elevated troponin levels and electrocardiogram abnormalities in these patients may help predict the occurrence of MACE.