Search

Calcineurin inhibitors (CNIs) have become the cornerstone of immunosuppressive regimens following heart transplantation, but their use is associated with nephrotoxicity. We evaluated a CNI elimination protocol in 14 patients with renal impairment at 48.3 +/- 36.0 months after heart transplantation. The mean serum creatinine was 321 +/- 107 micromol/L; cyclosporine (n=13) or tacrolimus (n=1) was discontinued with sirolimus commenced immediately, initially aiming for a target trough level of 16 (12 to 20) ng/mL. If patients were not receiving mycophenolate (MMF) this was initiated at 1 g bid. The transfer period was covered with a tapering course of corticosteroids. In addition to monitoring clinical status, hematology, biochemistry, and sirolimus levels, graft function was assessed by echocardiography, ECG, and, where indicated, endomyocardial biopsy. Renal function improved in 12 patients (with 6 having a greater than 40% decrease in serum creatinine), remained unchanged in 1, and deteriorated in 1. Two patients who were converted at 15 and 139 months after transplantation experienced grade 3A rejection. One patient experienced a fall in ejection fraction without histologic evidence of rejection. Sirolimus was discontinued in three patients because of side effects: bone marrow suppression, presumed lymphocytic pneumonitis, and generalized acneform rash complicated by an axillary abcess; 50% of patients continue on sirolimus. In conclusion, withdrawal of CNIs after heart transplantation resulted in an improvement in renal function in most patients: 43% experienced a substantial improvement. CNI elimination protocols need to be refined to reduce the risk of breakthrough rejection and to minimize side effects while protecting renal function after heart transplantation.

The discovery of cyclosporine proved to be a breakthrough that helped transform the status of both heart and lung transplantation from experimental to established therapeutic procedures. Cyclosporine inhibits the early phase of T-cell activation and thus of the alloimmune response. It proved to be highly effective in prophylaxis against acute rejection but its use has been limited by dose-related renal toxicity. Consequently, it has generally been used in regimens that combine it with other immunosuppressive agents with the aim of preventing acute rejection while minimising toxicity. For many years 'triple therapy' using cyclosporine, azathioprine and corticosteroids was the most commonly used regimen for both heart and lung transplantation. Other agents have now become available that provide more effective prophylaxis against acute rejection than azathioprine; these include, mycophenolate and the TOR inhibitors sirolimus and everolimus. Everolimus has also been shown to inhibit the early phase of cardiac allograft vasculopathy. Unfortunately, the TOR inhibitors also potentiate the nephrotoxicity of cyclosporine. Both mycophenolate and the TOR inhibitors are subject to pharmacokinetic interactions with cyclosporine. We are now entering a new phase of clinical immunosuppression where we need to learn how to best combine the agents that are currently available to provide the safest and most effective immunosuppression for patients undergoing heart or lung transplantation.