Mechanical Circulatory Support Combined With Immunosuppression for the Treatment of Giant Cell Myocarditis - A Single-Center Experience in Japan

Immunomodulatory Therapy for Giant Cell Myocarditis: A Narrative Review

Giant cell myocarditis (GCM) is a rare, often rapidly progressive, and potentially fatal disease because of myocardium inflammation due to the infiltration of giant cells triggered by infectious as well as non-infectious etiologies. Several studies have reported that GCM can occur in patients of all ages but is more commonly found in adults. It is relatively more common among African American and Hispanic patients than in the White population. Early diagnosis and treatment are critical. Electrocardiogram (EKG), complete blood count, erythrocyte sedimentation rate, C-reactive protein, and cardiac biomarkers such as troponin and brain natriuretic peptide (BNP), echocardiogram, cardiac magnetic resonance imaging (MRI), myocardial biopsy, and myocardial gene profiling are useful diagnostic tools. Current research has identified several potential biomarkers for GCM, including myocarditis-associated immune cells, cytokines, and other chemicals. The standard of care for GCM includes aggressive immunosuppressive therapy with corticosteroids and immunomodulatory agents like rituximab, cyclosporine, and infliximab, which have shown promising results in GCM by balancing the immune system and preventing the attack on healthy tissues, resulting in the reduction of inflammation, promotion of healing, and decreasing the necessity for cardiac transplantation. Without immunosuppression, the chance of mortality or cardiac surgery was 100%. Multiple studies have revealed that a treatment combination of corticosteroids and immunomodulatory agents is superior to corticosteroids alone. Combination therapy significantly increased transplant-free survival (TFS) and decreased the likelihood of heart transplantation, hence improving overall survival. It is important to balance the benefits of immunosuppression with its potentially adverse effects. In conclusion, immunomodulatory therapy adds significant long-term survival benefits to GCM.

Successful bridge to recovery in a patient with fulminant giant cell myocarditis that developed from multiple autoimmune disorders including myasthenia gravis: a case report

Background

A recently indicated immunotherapy strategy, combined with mechanical circulatory support (MCS), seems to improve outcomes in patients with fulminant giant cell myocarditis (GCM). However, characterizing a definitive clinical outcome of this strategy remains challenging, and the autoimmunity associated with the onset of GCM remains controversial.

Case summary

A 26-year-old man with poor control of atopic dermatitis and ulcerative colitis presented with cardiogenic shock requiring MCS. He was diagnosed with fulminant GCM; hence, immunotherapy (including steroids and intravenous immunoglobulin) was administered and an extracorporeal left ventricular assist device (LVAD) was needed. As the patient complained of prominent fatigue and double vision before myocarditis onset, and acetylcholine receptor-binding antibody titres were elevated, he was diagnosed with myasthenia gravis (MG). No anti-striational antibodies known to be associated with GCM in patients with MG were found in the patient’s serum. Cyclosporin-based immunosuppression under LVAD therapy led to an almost complete resolution of his muscle weakness, intermittent ptosis, and cardiac dysfunction along with the histopathological remission of GCM resulting in LVAD removal. He remained at home without recurrence of GCM and worsening symptoms of MG over the 6-month period following discharge.

Discussion

We describe a case of GCM with multiple autoimmune disorders, which recovered by treatment with early cyclosporin-based immunosuppressive therapy under LVAD therapy. The present case suggests the involvement of unknown anti-striational antibodies in the development of GCM in patients with MG and may provide information to guide a novel therapeutic regimen for patients with fulminant GCM requiring mechanical circulatory support.

Clinical Identification and Characteristic Analysis of Giant Cell Myocarditis in 12 Cases

Aims: Giant cell myocarditis (GCM) is a rare, rapidly progressing cardiomyopathy with high mortality, if not diagnosed and treated in time. We analyzed the progression and clinical manifestations of patients with definitive diagnosis of GCM.

Methods and Result: We enrolled 12 patients diagnosed with GCM in the explanted heart during heart transplantation (HTx) or by endomyocardial biopsy (EMB) and collected information on demographic data, cardiac structure and function, arrhythmias, preliminary diagnosis, and delay of the diagnosis. Seven cases were diagnosed from biopsy samples during HTx, and five cases were diagnosed through EMB. Before the diagnosis of GCM based on pathological analysis, these patients had been incorrectly diagnosed with arrhythmogenic right ventricular cardiomyopathy (n = 5), dilated cardiomyopathy (n = 2), ventricular tachycardia (n = 2), viral myocarditis (n = 1), cardiac amyloidosis (n = 1), and ischemic cardiomyopathy (n = 1) based on clues such as symptoms, arrhythmia, and cardiac imaging. Patients diagnosed with GCM through EMB had a shorter symptom-onset-to-diagnosis time (6.6 ± 2.7 months) and milder heart damage (left ventricular ejection fraction, 47.2 ± 8.8%) than those diagnosed during HTx (11.0 ± 3.3 months, P = 0.034; 31.4 ± 10.9%, P = 0.024).

Conclusion: GCM is easily misdiagnosed as other types of myocarditis and cardiomyopathy. Pathological examination of the myocardium is the most reliable diagnostic method for GCM. Endocardial biopsy can identify patients with GCM at an earlier stage.