The purpose of this study is to improve or save renal function by optimizing the immunosuppressive regimen by reducing the Cyclosporine A dose and the exchange of Azathioprine by Mycophenolatmofetile, which is an effective immunosuppressive agent and will minimize the risk of acute rejection episodes.

The decrease of quality of life in patients after heart transplantation in the long-term is determined by an increasing incidence of transplant vasculopathy and by immunosuppression-related side effects.Long-term administration of calcineurin inhibitors is associated with chronic nephrotoxicity.

Inclusion Criteria:

• Current immunosuppressive regimen: Cyclosporine A, Azathioprine and corticosteroids for at least 12 month
• Heart transplantation above 3 years dated back
• Serum creatinine < 3,5 mg/dl (310 µmol/l) and BUN < 150 mg/dl
• Cyclosporine A blood level between 50 and 250 ng/ml during the last 12 month

Exclusion Criteria:

• Carcinoma within the last 3 years
• Acute rejection episodes during the last 6 month
• Infection requiring therapeutic intervention
• Hepatitis B, Hepatitis C or HIV infection
• WBC < 3000/µl, haemoglobin < 9g/dl, platelets < 70.000/µl
• Florid gastrointestinal ulcer
• Haemodialysis within the last 4 weeks before study entry
• Pregnancy / lactation
• Administration of other immunosuppressive agents than prescribed
• Mycophenolatmofetile incompatibility