Myocyte hypertrophy in the transplanted heart a morphometric analysis

In order to better define long-term changes in the transplanted heart with respect to the effects of cyclo-sporine and the ischemic time of the donor heart, endomyocardial biopsies were examined ultrastructurally from 20 cardiac transplant recipients three years posttransplantation. The biopsies were divided into four groups of five based on the donor heart ischemic time in “on-site” versus “distantly procured” hearts and on the immunosuppression protocol: group A: “on site” donor hearts and cyclosporine-based immunosuppression; group B: “on site” donor hearts with conventional immunosuppression (azathioprine-based immunosuppression without cyclosporine); group C: distantly procured donor hearts treated with cyclosporine; and group D: distantly procured donor hearts treated with conventional immunosuppression. All four groups showed a significant increase in the average width of myocytes when compared with normal myocardium, (group A, P<0.05; groups B, C, D, P<0.01). Also, there was a significant difference between the average widths of myocytes from on-site donor hearts and distantly procured donor hearts (P<0.04). There was no significant difference between the average myocyte widths of groups treated with cyclosporine and those with conventional immunosuppression. This study shows that despite the hypertension induced by cyclosporine, myocyte hypertrophy at 3 years posttransplantation does not appear to be significantly greater than in patients treated with conventional immunosuppression. Distantly procured donor hearts have more hypertrophy. Due to the increasing evidence that cardiac hypertrophy per se may predispose to serious ventricular arrhythmias, this study supports the use of on-site as opposed to distantly procured donor hearts.