Idiopathic Giant Cell Myocarditis

Idiopathic giant cell myocarditis (IGCM) is an uncommon disorder that is of general importance because it most commonly affects young individuals, is usually fatal without treatment, and may respond to aggressive medical and surgical therapy. IGCM is most often progressive over days to weeks and frequently requires the concurrent management of congestive heart failure, tachyarrhythmias, and heart block. After common causes of heart disease are excluded, the diagnosis must be confirmed by endomyocardial biopsy. Standard pharmacologic therapy for New York Heart Association functional class II to III congestive heart failure due to left ventricular systolic failure includes an angiotensin-converting enzyme inhibitor, a beta-blocker such as carvedilol, and diuretics as needed. We avoid digoxin and reserve inotropic agents for patients whose circulatory requirements cannot be supported with standard oral vasodilators and diuretics. Heart block may require a temporary or permanent pacemaker. Ventricular tachycardia is common and usually is managed chronically with an implantable cardiac defibrillator and antiarrhythmic drugs such as amiodarone. Despite optimal medical management, mechanical support may be required as a temporary bridge to recovery or transplantation. The intra-aortic balloon pump and ventricular assist device have been used successfully for patients with refractory pump failure due to acute IGCM. Heart transplantation is efficacious, with a 71% 5-year survival, despite a 20% to 25% rate of histologic recurrence in surveillance endomyocardial biopsies. The role of aggressive immunosuppression as part of the primary treatment of IGCM is under active investigation. Preliminary data suggest that primary therapy with a regimen that includes muromonab-CD3, cyclosporine, and steroids may significantly improve transplant-free survival.