Diagnosis, treatment, and outcome of giant-cell myocarditis in the era of combined immunosuppression.

Background: Giant-cell myocarditis often escapes diagnosis until autopsy or transplantation and has defied proper treatment trials for its rarity and deadly behavior. Current therapy rests on multiple-drug immunosuppression but its prognostic influence remains poorly known. We set out to analyze (1) our experience in diagnosing giant-cell myocarditis and (2) the outcome of patients on combined immunosuppression.

Methods And Results: We reviewed the histories, diagnostic procedures, details of treatment, and outcome of 32 consecutive patients with histologically verified giant-cell myocarditis treated in our hospital since 1991. Twenty-six patients (81%) were diagnosed by endomyocardial or surgical biopsies and 6 at autopsy or post-transplantation. Twenty-eight (88%) patients underwent endomyocardial biopsy. The sensitivity of transvenous endomyocardial biopsy increased from 68% (19/28 patients) to 93% (26/28) after up to 2 repeat procedures. The 26 biopsy-diagnosed patients were treated with combined immunosuppression (2-4 drugs) including cyclosporine in 20 patients. The Kaplan-Meier estimates of transplant-free survival from symptom onset were 69% at 1 year, 58% at 2 years, and 52% at 5 years. Of the transplant-free survivors, 10/17 (59%) experienced sustained ventricular tachyarrhythmias during follow-up and 3 received intracardiac defibrillator shocks for ventricular tachycardia or fibrillation.

Conclusions: Repeat endomyocardial biopsies are frequently needed to diagnose giant-cell myocarditis. On contemporary immunosuppession, two thirds of patients reach a partial clinical remission characterized by freedom from severe heart failure and need of transplantation but continuing proneness to ventricular tachyarrhythmias.