From the Guidelines
Post cardiac transplant organ rejection is primarily antibody-mediated rejection (AMR), which occurs when recipient antibody is directed against donor HLA antigens on the endothelial layer of the allograft, as stated in the 2015 American Heart Association scientific statement 1.
Types of Rejection
- Acute cellular rejection is the most common type, occurring in 30-40% of heart transplant recipients, especially within the first six months post-transplantation, as it is mediated by T-lymphocytes recognizing the donor heart as foreign.
- Antibody-mediated (humoral) rejection can also occur, where antibodies target the donor heart's blood vessels, causing damage, and is characterized by the deposition of complement and immunoglobulin within the allograft microvasculature 1.
- Chronic rejection, characterized by cardiac allograft vasculopathy (CAV), involves progressive narrowing of the coronary arteries in the transplanted heart.
Prevention and Monitoring of Rejection
To prevent rejection, patients typically receive a triple immunosuppression regimen consisting of a calcineurin inhibitor (tacrolimus or cyclosporine), an antiproliferative agent (mycophenolate mofetil), and corticosteroids (prednisone) 1. Dosing is individualized based on drug levels, with tacrolimus typically maintained at 8-12 ng/mL early post-transplant. Regular endomyocardial biopsies are performed to monitor for rejection, especially in the first year, as the diagnosis of acute cellular rejection is made by histological identification of interstitial leukocyte infiltration with various degrees of myocyte damage 1.
Importance of Balancing Immunosuppression
The balance of immunosuppression is crucial, as too little risks rejection while too much increases infection and malignancy risks. Approximately 50% of heart transplant recipients who develop rejection >7 years after transplantation have evidence of AMR, highlighting the need for ongoing monitoring and adjustment of immunosuppressive therapy 1.
From the Research
Post Cardiac Transplant Organ Rejection
- Post cardiac transplant organ rejection is a type of acute cellular rejection 2, 3, 4, 5, 6
- This type of rejection occurs when the immune system recognizes the transplanted heart as foreign and attacks it 2, 3, 4, 5, 6
- Acute cellular rejection is a common problem after heart transplantation, despite the use of immunosuppressive drugs 2, 3, 4, 5, 6
Characteristics of Acute Cellular Rejection
- Acute cellular rejection can occur at any time after transplantation, but it is most common in the first few months 2, 3, 4, 5, 6
- It can be caused by a variety of factors, including the immune system's response to the transplanted heart, infections, and other medical conditions 2, 3, 4, 5, 6
- Symptoms of acute cellular rejection can include shortness of breath, fatigue, and chest pain 2, 3, 4, 5, 6
Treatment of Acute Cellular Rejection
- Treatment of acute cellular rejection typically involves the use of immunosuppressive drugs, such as tacrolimus 2, 3, 4, 6
- Tacrolimus has been shown to be effective in reducing the incidence of acute cellular rejection and improving patient outcomes 2, 3, 4, 6
- Other treatments, such as steroids and monoclonal antibodies, may also be used to treat acute cellular rejection 2, 3, 4, 5, 6