Giant Cell Myocarditis: An Updated Review of Pathogenesis, Clinical Presentation, and Modern Management Approaches

Giant cell myocarditis is a rare cardiac disorder that can lead to rapid deterioration and poor outcomes. It presents with a wide array of symptoms, including heart failure, ventricular arrhythmias, or atrioventricular block. Its features overlap with other inflammatory cardiac conditions, particularly cardiac sarcoidosis, which can lead to diagnostic challenges. Diagnostic modalities, including cardiac magnetic resonance and positron emission tomography, can detect myocardial inflammation but are not diagnostic. Endomyocardial biopsy remains a gold standard, showing a diffuse inflammatory infiltrate with multinucleated giant cells and extensive myocyte necrosis. Management involves prompt initiation of immunosuppressive treatment, as well as management of the cardiac complications when indicated. Despite treatment, mechanical circulatory support or cardiac transplantation is required in numerous patients, and recurrence in the allograft has been noted. In this review, we discuss the clinical presentation, diagnostic strategy, differential diagnosis with sarcoidosis, and modern treatment options for giant cell myocarditis, emphasizing early diagnosis and newer therapies.