A Fatal Case of Immune Checkpoint Inhibitor-Associated Myocarditis with Severe Right Ventricular Failure

A 70-year-old man with esophageal cancer undergoing nivolumab treatment presented to our hospital with suspected myocarditis associated with immune checkpoint inhibitor (ICI) therapy. The initial echocardiographic assessment upon admission demonstrated a preserved left ventricular (LV) ejection fraction but impaired right ventricular (RV) function. An endomyocardial biopsy revealed significant lymphocytic infiltration and myocyte necrosis. High-dose steroid therapy was initiated on the day of admission. However, on the following day, RV function deteriorated further, and LV dysfunction emerged, resulting in hemodynamic collapse and necessitating mechanical circulatory support. Despite additional immunoglobulin therapy, cardiac function failed to improve, and the patient died 9 days after admission. This case underscores the critical need for vigilant monitoring of both LV and RV function in patients undergoing ICI therapy to detect and manage potential cardiovascular complications promptly.