Patients with severe ICIs-related myocarditis are characterized by early onset, multisystem involvement, marked elevation of cardiac enzymes, prominent electrocardiographic/echocardiographic abnormalities, frequent concomitant irAEs, and high mortality of 32%.
Severe ICI-related myocarditis had significantly earlier onset compared to mild cases.
Severe ICI-related myocarditis was associated with significantly higher rates of multisystem clinical manifestations including myasthenia, dyspnea, and ptosis.
Cardiac biomarkers and liver enzymes were markedly elevated in the severe group compared to the mild group.
Electrocardiographic abnormalities were significantly more frequent in the severe group than in the mild group.
Echocardiographic abnormalities including regional wall motion abnormality and pericardial effusion were more common in severe cases.
Severe ICI-related myocarditis was associated with higher rates of concurrent immune-related adverse events (irAEs) including myositis, hepatitis, and neurotoxicity.
Severe ICI-related myocarditis required substantially more intensive treatment compared to mild cases.
Mortality in the severe ICI-related myocarditis group was 32%, while all patients in the mild group recovered.
This research examined 74 patients who developed heart inflammation (myocarditis) as a side effect of immune checkpoint inhibitor (ICI) cancer treatments between 2020 and 2024. The patients were divided into mild (49 patients) and severe (25 patients) groups. The study found that severe cases tended to appear much earlier after starting treatment — about 23 days compared to 80 days for mild cases — and were associated with symptoms affecting multiple body systems, such as muscle weakness, drooping eyelids, and difficulty breathing. Severe cases also showed dramatically higher levels of heart damage markers in the blood, more abnormalities on heart tracings (ECGs) and ultrasounds, and were more likely to involve simultaneous inflammation of muscles, the liver, and the nervous system. The treatment differences between groups were stark: all severe patients needed steroid medications (glucocorticoids), 60% needed intravenous immunoglobulin, and over a quarter required breathing support — compared to less than a third of mild patients needing any steroids at all. The consequences were also very different: every patient in the mild group recovered, but nearly one in three patients in the severe group (32%) died. This research suggests that early warning signs — such as muscle weakness appearing shortly after starting ICI therapy, abnormal electrical conduction in the heart, or sharply elevated blood levels of creatine kinase and cardiac troponin — should prompt clinicians to act quickly with aggressive treatment. The findings provide a clearer picture of what distinguishes life-threatening ICI-related myocarditis from milder forms, which could help doctors identify and treat the most dangerous cases sooner.
Wang R, Hao C, Liu J, Zhang Z, Qin S. (2026). Clinical characteristics analysis of immune checkpoint inhibitors-related myocarditis.. Frontiers in immunology. https://doi.org/10.3389/fimmu.2026.1904778