Successful Management of Fulminant Immune Checkpoint Inhibitor-Associated Myocarditis Amid Corticosteroid Constraints and Clinical-Biomarker Dissociation.

[BACKGROUND] Immune checkpoint inhibitor (ICI)-associated myocarditis is an uncommon but life-threatening complication. Management is particularly challenging when high-dose corticosteroids are contraindicated and in the presence of clinical-biomarker dissociation.

[CASE SUMMARY] A 69-year-old man presented with cardiogenic shock and ventricular tachycardia 3 weeks after his first dose of pembrolizumab for lung adenocarcinoma. Despite corticosteroid constraints owing to pulmonary tuberculosis and the complexity of clinical decision-making during tapering with rebound troponin T elevation, the patient achieved favorable long-term survival.

[DISCUSSION] This case demonstrates a successful management strategy for fulminant ICI-associated myocarditis under the dual constraints of limited corticosteroid use and persistent biomarker elevation, offering valuable clinical insights.

[TAKE-HOME MESSAGES] Rebound elevation of troponin T levels may indicate myocardial remodeling rather than active injury, supporting corticosteroid tapering in clinically stable patients. In patients with ICI-associated myocarditis and contraindications to corticosteroids, early steroid tapering combined with alternative immunosuppressive therapy may still achieve favorable outcomes.