Immune Checkpoint Inhibitor-Induced Myocarditis: A Review of Published Cases

Abstract

ackground: Immune checkpoint inhibitors (ICIs) targeting CTLA-4, PD-1 and PD-L1 have transformed treatment of metastatic
melanoma and other cancers, but the same mechanism that unleashes anti-tumour immunity can also attack the myocardium.
Objective: To review the published case reports, series, registries and mechanistic literature on ICI myocarditis, drawing on
melanoma-specific reports where the literature specifies them. Methods: Narrative review of case reports, case series,  pharmacovigilance analyses, registry cohorts, mechanistic studies and guideline documents. Findings: Reported incidence ranges from roughly 0.06% to 1.3% of ICI-treated patients, rising toward 2% with combination therapy. Onset is typically early (median 34 days, one registry of 35 patients), and historical fatality has reached 25-50%. Published cases document fulminant presentations with conduction abnormalities, cardiogenic shock and myositis; refractory cases have been treated with anti-thymocyte globulin, abatacept and ruxolitinib, the latter combination linked in one cohort to a marked fatality reduction. Conclusions: The published record supports early biomarker-based suspicion, prompt ICI discontinuation, and stepwise escalation of immunosuppression in refractory disease, with still-limited evidence for targeted second-line agents.