Fatal Immune Checkpoint Inhibitor-associated Myocarditis Mimicking Infiltrative Cardiomyopathy in a 54-year-old Woman with Metastatic Melanoma

Abstract

Introduction: Immune checkpoint inhibitors (ICI) have significantly improved cancer treatment outcomes, but cardiovascular complications such as ICI-associated myocarditis are a major concern. Diagnosing myocarditis requires integrating biomarkers, electrocardiogram (EKG), cardiac imaging, and endomyocardial biopsy. We present a case illustrating these diagnostic challenges, involving a female patient treated with pembrolizumab who developed fatal acute myocarditis mimicking infiltrative cardiomyopathy. Case report: A 54-year-old woman with mucosal melanoma, treated with pembrolizumab, was hospitalized in May 2023 due to dyspnea and elevated troponin levels. Initial cardiac workups were normal, but subsequent tests revealed borderline cardiac magnetic resonance imaging findings. In late May 2023, the patient was admitted with worsening dyspnea, elevated NT-pro-BNP, and severe hyperlactatemia. Imaging and endomyocardial biopsy confirmed acute myocarditis with atypical presentation, mimicking infiltrative cardiomyopathy. Despite aggressive immunosuppressive therapy, the patient’s condition deteriorated, resulting in cardiogenic shock and death seven days post-admission. Conclusion: This case underscores the diagnostic and management challenges of ICI-associated myocarditis, particularly with atypical presentations. It highlights the need for vigilant, comprehensive monitoring and further research to improve diagnostic and therapeutic strategies for managing these severe side effects in patients undergoing ICI therapy.