FK506 vs. cyclosporin - Pathologic findings in 1067 endomyocardial biopsies

Introduction: Whether FK506 or cyclosporin is better for chronic immunosuppression in heart transplant patients has been debated. We examined endomyocardial biopsies from patients treated with these two drugs to determine if there was a difference in frequency of histologic cellular rejection episodes and Quilty lesions. The Quilty lesion (AKA cyclosporin effect) may be an atypical form of rejection, and is thought to be related to the use of cyclosporin immunosuppression. Methods: We reviewed 1067 endomyocardial biopsies from 65 patients who were assigned FK506 or cyclosporin after heart transplantation. Results: The number of episodes of rejection (162 FK506 vs. 145 cyclosporin) was the same. However, when compared to cyclosporin treatment, FK506 was associated with significantly more Quilty A lesions and fewer Quilty B lesions. Conclusion: FK506 appears to prevent some Quilty A lesions from progressing to Quilty B lesions. Since Quilty B lesion is associated with myocyte injury and Quilty A is not, this effect of FK506 could be associated with improved long-term graft function. (C) 2003 Elsevier Inc. All rights reserved.