Conversion from cyclosporine to azathioprine following heart transplantation.

Eleven patients receiving cyclosporine were converted to azathioprine immunosuppression because of persistent creatinine elevation greater than 2 mg/dl 6 months or more following heart transplantation. During conversion, the maintenance steroid dose was doubled for 3 months then tapered to the preconversion dose. Pretransplant renal function in these converted patients was similar to that in a group of azathioprine patients and a group of nonconverted cyclosporine patients. One year following transplant, the nonconverted group had stable but impaired renal function (mean creatinine, 1.45 +/- 0.06 mg/dl; effective renal plasma flow, 407 +/- 39 ml/min; glomerular filtration rate, 68 +/- 8.8 ml/min). The converted patients had evidence of progressive renal dysfunction (mean creatinine, 2.65 +/- 0.19 mg/dl; effective renal plasma flow, 193 +/- 16 ml/min; glomerular filtration rate, 29 +/- 5.1 ml/min). Following conversion, renal function improved toward normal in all patients. There were three episodes of rejection that were successfully treated. An important number of infective and noninfective complications occurred following conversion during the period of steroid augmentation. There were two deaths during the follow-up period. Conversion can be undertaken with low risk of rejection, death, or both, but protocols that employ prolonged periods of steroid augmentation are associated with important morbidity.