This is a study to determine the efficacy of muromonab-CD3 and cyclosporine as treatment in patients with giant cell myocarditis (GCM). T lymphocytes appear to be involved in GCM. Muromonab-CD3 has been shown to reduce the number of lymphocytes and cyclosporine inhibits lymphocyte activation. This treatment may prolong patient survival until transplantation or ventricular assist device placement is possible.

Each patient will be randomized to receive either standard care and immunosuppression therapy (treatment group) or standard care alone (control group). To prevent bias, randomization will be stratified by recency of symptom onset to ensure that both the treatment and control groups are balanced with respect to it. Within each of these 2 strata, permuted-block randomization will be done to keep the number of treatment and control patients balanced. Due to the necessary monitoring of the patients randomized to receive immunosuppression therapy, treatment cannot be blinded. Approximately 1 year after the last patient has been randomized, the observed times from randomization to the composite endpoint (death, transplantation, or LVD placement) will be compared in the treatment and control groups.

Completion date provided represents the completion date of the grant per OOPD records

Inclusion criteria:

• Idiopathic heart failure and/or arrhythmia of less than 3 months duration
• Endomyocardial biopsy diagnostic of idiopathic giant cell myocarditis
• Negative pregnancy test

Exclusion criteria:

• Clinical evidence of sepsis or active infection (e.g., meningitis or osteomyelitis)
• Pregnant
• Any contraindication to immunosuppression
• Allergy to cyclosporine or muromonab-CD3
• Creatinine greater than 2.5 mg/dL
• AST or ALT greater than 3 times upper limit of normal
• Other severe concurrent disease that would preclude study
• Unreliable or uncooperative subject