Giant Cell Myocarditis Presenting With Cardiogenic Shock: Diagnostic and Therapeutic Challenges

Abstract

Giant cell myocarditis (GCM) is a rare but often fatal inflammatory cardiomyopathy characterized by aggressive myocardial inflammation and necrosis. Prompt recognition and immunosuppressive therapy are critical for improving outcomes. A 48-year-old woman with no prior cardiac history presented with dyspnea, orthopnea, and hypotension. Electrocardiography showed wide complex tachycardia with retrograde V-to-A conduction. Laboratory findings revealed rising high-sensitivity troponin, hepatic injury, and leukocytosis. Echocardiography showed biventricular failure, and cardiac magnetic resonance imaging showed myocardial edema and subepicardial enhancement. Endomyocardial biopsy confirmed GCM. Immunosuppressive therapy with corticosteroids, tacrolimus, and mycophenolate mofetil led to clinical improvement, avoiding transplantation. GCM remains a diagnostic and therapeutic challenge due to its rapid progression and arrhythmic burden. This case highlights the importance of early biopsy, tailored immunosuppression, and vigilant monitoring in managing fulminant myocarditis.

Keywords: endomyocardial biopsy; giant cell myocarditis; immunosuppression.

Graphical abstract

Figure 1

Electrocardiographic Data (A) Electrocardiogram (ECG) on presentation shows sinus rhythm, right bundle branch block (RBBB), left anterior fascicular block, and prolonged QTc (523 ms). (B) Accelerated idioventricular rhythm (heart rate, 97 beats/min). Notice the change in RBBB morphology compared to ECG shown in A, positive aVR, and fusion beats (complexes 11 and 15). (C) Slow ventricular tachycardia (heart rate, 111 beats/min). Capture beats (complexes 12 and 13), fusion beat (complex 8), and atrioventricular dissociation. (D) Ventricular tachycardia (heart rate, 126 beats/min).

Figure 2

Clinical Data Used in Diagnosis and Management of Giant Cell Myocarditis (A) Trends in right heart catheterization (RHC) pressures and cardiac output (CO) and cardiac index (CI) over time. The left y-axis represents right atrial pressure (RAP) (green), mean pulmonary arterial pressure (mPAP) (blue), pulmonary capillary wedge pressure (PCWP) (orange), and cardiac output (CO) (red). The right y-axis represents CI (purple). The trends show an overall decline in filling pressures and improvement in CO and CI following treatment initiation. (B) Trends in alanine aminotransferase (ALT), high-sensitivity (Hs)–troponin T, and left ventricular function (LVEF) over time. The left y-axis represents ALT (orange), showing a progressive decline, consistent with hepatic recovery. The right y-axis represents Hs-troponin T (green) and LVEF (blue), showing a reduction in myocardial injury and gradual improvement in LVEF with immunosuppressive therapy. (A, B) The gold star represents dobutamine 5 μg/kg/min. The red triangle represents triple immunosuppressive therapy started with high-dose intravenous methylprednisolone (1 g/d), tacrolimus (3 mg twice daily), and mycophenolate mofetil (1,000 mg twice daily). The green star represents dobutamine 2.5 μg/kg/min. The blue star represents dobutamine discontinued. (C) Hematoxylin and eosin stain (original magnification ×400). Endomyocardium with myocyte loss and scattered, multinucleated giant cells (arrows). (D) Short-axis right ventricle (RV) and left ventricle (LV) views on a cardiac magnetic resonance image revealed abnormal delayed subepicardial enhancement involving base to distal anterior, anteroseptal, and anterolateral walls (red arrows). Normal left ventricular size and thickness.