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A prospective randomized study of prophylactic OKT3 versus equine antithymocyte globulin after heart
P S Macdonald1, J Mundy, A M Keogh
1Cardiopulmonary Transplant Unit, Saint Vincent's Hospital, Sydney, Australia.
Insights
Prophylactic OKT3 and equine antithymocyte globulin (ATGAM) show similar heart transplant rejection rates and survival. However, OKT3 increases viral infections and adverse reactions, suggesting ATGAM is more suitable for rejection prophylaxis.
Area of Science:
- Immunosuppression
- Transplantation Immunology
- Pharmacology
Background:
- Heart transplantation requires effective immunosuppression to prevent rejection.
- Prophylactic cytolytic agents are used to reduce early rejection episodes.
- Comparing OKT3 and equine antithymocyte globulin (ATGAM) is crucial for optimizing post-transplant care.
Purpose of the Study:
- To compare the efficacy and toxicity of prophylactic OKT3 versus equine antithymocyte globulin (ATGAM) after heart transplantation.
- To evaluate rejection rates, patient survival, and adverse events associated with each agent.
Main Methods:
- A randomized study of 41 heart transplant patients.
- Patients received either OKT3 (10 days) or ATGAM (8 days) alongside triple-agent immunosuppression.
- Follow-up duration was a mean of 14 months.
Main Results:
- Comparable 12-month actuarial survival (83% OKT3 vs. 81% ATGAM) and rejection rates between groups.
- Significantly higher incidence of viral infections in the OKT3 group (1.6 vs. 0.8 infections/patient).
- Increased adverse reactions, including acute respiratory distress, in the OKT3 group.
Conclusions:
- Prophylactic OKT3 and ATGAM demonstrate comparable efficacy in preventing rejection and ensuring survival post-heart transplant.
- OKT3 is associated with greater morbidity due to increased adverse reactions and viral infections.
- Equine antithymocyte globulin (ATGAM) appears to be a more suitable agent for rejection prophylaxis in heart transplantation.
Abstract:
The aim of this study was to compare the efficacy and toxicity of prophylactic OKT3 and equine antithymocyte globulin when each drug was administered for a similar duration after heart transplantation. Forty-one patients (35 males, 6 females; mean age 46 +/- 2 years) were randomized to receive either OKT3 for 10 days (20 patients) commencing within 24-48 hr of transplantation or ATGAM for 8 days (21 patients) commencing on the day of transplantation. All patients were maintained on triple-agent immunosuppression with prednisolone, azathioprine, and cyclosporine. The two groups were well matched with respect to age, sex distribution, pretransplant cardiac diagnosis, and donor heart ischemic time. Mean duration of follow-up was 14 months (range 9-19 months): Actuarial survival at 12 months was 83 +/- 9 in the OKT3 group and 81 +/- 9 in the ATG group (P = NS). Mean time to first cardiac rejection was 33 +/- 8 days in the OKT3 group compared with 27 +/- 5 days in the ATG group (P = NS). Linearized rejection rate did not differ between the two groups at any time point up to 12 months posttransplant. Viral infections were significantly more common in the OKT3 group: 1.6 +/- 0.3 vs. 0.8 +/- 0.2 infections per patient (P < 0.05). Adverse reactions were more common in patients who received OKT3 prophylaxis and included three patients who developed acute respiratory distress, two of whom required assisted ventilation. In conclusion, prophylactic OKT3 and ATGAM result in comparable rejection rates and survival when administered for a similar duration after cardiac transplantation. OKT3, however, is associated with increased morbidity due to a higher incidence of adverse reactions and of viral infections. These findings suggest that ATGAM is the more suitable cytolytic agent for rejection prophylaxis after heart transplantation.