Clinical Characteristics, Management Patterns, and Outcomes of Immune Checkpoint Inhibitor-Associated Myocarditis: A Single-Center Retrospective Descriptive Study

Immune checkpoint inhibitor-associated myocarditis (ICI-AM) is rare but potentially fatal. We retrospectively reviewed pre-existing clinical records of 42 patients diagnosed with ICI-AM at Renmin Hospital of Wuhan University between October 2023 and March 2025 and classified them as mild (grade 1–2, n = 29) or severe (grade 3–4, n = 13). Baseline characteristics, electrocardiographic findings, biomarkers, treatment patterns, and clinical outcomes were summarized descriptively. Follow-up information was retrospectively obtained from available clinical records, with an administrative follow-up end date of 31 January 2026. Severe ICI-AM was characterized by more frequent dyspnea, concomitant myasthenia gravis, electrocardiographic abnormalities, and higher troponin, CK-MB, and myoglobin levels, together with more frequent corticosteroid, intravenous immunoglobulin, and additional immunosuppressive treatment. Concomitant myositis was also more frequently observed in severe cases. During follow-up, 13 patients (31.0%) died, including 6 of 13 (46.2%) patients with severe ICI-AM and 7 of 29 (24.1%) with mild ICI-AM. Severe ICI-AM showed a more clinically overt phenotype, frequent neuromuscular involvement, and substantial all-cause mortality. These descriptive findings highlight the clinical heterogeneity of ICI-AM and require further investigation in larger prospective multicenter studies.