1438: Diagnostic and Therapeutic Challenges of a Rapidly Progressive Case of Giant Cell Myocarditis

Introduction: Early diagnosis of any form of myocarditis is critical but challenging due to its nonspecific initial presentation and overlap with other forms of cardiomyopathy. We present a rare but most fatal form of myocarditis- Giant cell myocarditis with rapidly progressive heart failure and ventricular arrhythmia. Description: A 44-year-old female with a history of hypertension and iron deficiency anemia presented with epigastric pain and progressive dyspnea. On admission, she was in cardiogenic shock with elevated lactic acid to 5 mmol/L. ECG revealed low voltage and nonspecific ST changes. Troponin I was elevated at 45 ng/mL, and BNP was 8,500 pg/mL. She was found to be positive for RSV. Transthoracic echocardiogram revealed severe biventricular failure with severely reduced LVEF of 10%. She was escalated on inotrope and an intra-aortic balloon pump for cardiac output support. Endomyocardial biopsy performed did not show any inflammatory infiltrate. Ventricular arrhythmias complicated the course. High-dose corticosteroids were initiated immediately. Her cardiac output did not improve, and the patient was listed for orthotopic heart transplant. Eventually, the patient underwent an orthotopic heart transplant. Heart cytology revealed giant cell myocarditis. Post-transplant, LVEF was 58% with good RV function. The patient was discharged in an improved condition with immunosuppression. Discussion: Giant cell myocarditis (GCM) is a rare but fatal form of myocarditis. This case highlights the challenges in diagnosing a fulminant myocarditis. While viral myocarditis is the most common cause in this setting, GCM should be considered, especially in the context of arrhythmias or rapid deterioration. Immunosuppression is the mainstay of therapy. If the patient does not improve with immunosuppression, Orthotopic Heart Transplant is the next best treatment option. Her poor response to immunosuppression underscores the role of aggressive, multidisciplinary management in giving a heart transplant to improve outcomes.