Abstract
BACKGROUND: Immune checkpoint inhibitors (ICIs) enhance T-cell activity against cancer, but can cause immune-related adverse events, including myocarditis, a rare yet potentially fatal complication. Cardiac troponin I (cTnI) is widely used for screening the development of myocarditis, but its efficacy remains uncertain. METHODS AND RESULTS: From January 2016 to June 2024, we conducted a single-center retrospective study of 468 cancer patients receiving ICI therapy. Serum cTnI levels were assessed at baseline, at 1, 3, 6, 9, 12 months, and every 4 months. During the follow-up period, 26 patients (5.6%) exhibited cTnI elevation. This group had a higher prevalence of breast cancer, higher baseline cTnI levels, lower estimated glomerular filtration rates, and a greater proportion of concomitant ipilimumab and nivolumab use. Multivariate analysis revealed that high baseline cTnI levels and concomitant ipilimumab and nivolumab use were independent predictors of cTnI elevation. Of the 26 patients with elevated cTnI, 4 developed myocarditis, requiring steroid therapy, and exhibited a progressive increase in cTnI levels, whereas the remaining 22 patients without myocarditis did not show such an increase. CONCLUSIONS: Occasional cTnI elevation occurs during ICI therapy. However, a marked and sustained increase in cTnI levels may be a sign of the development of myocarditis.