Systematic Review of Allograft Rejection Rates in Cardiac Transplant Recipients

Heart transplantation continues to be a vital treatment for advanced heart failure, but rejection of the donor heart presents a major obstacle to prolonged patient survival. Despite advances in immunosuppressive therapies, rejection rates vary widely, and the underlying mechanisms remain incompletely understood. This systematic review aims to synthesize existing evidence on the incidence, risk factors, detection methods, and management strategies for cardiac allograft rejection, while also exploring the molecular and immunological basis of graft dysfunction. We performed an extensive analysis of peer-reviewed studies, with particular attention to acute and chronic rejection phenotypes, covering antibody-mediated and cellular rejection, along with cardiac allograft vasculopathy. Our findings highlight the multifactorial nature of rejection, with donor-specific antibodies, HLA mismatches, and non-adherence to immunosuppression emerging as key contributors. Non-invasive diagnostic tools, such as gene expression profiling and imaging modalities, show promise but require further validation. Therapeutic approaches increasingly emphasize personalized immunosuppression, though balancing efficacy with adverse effects remains challenging. Mechanistic understanding clarifies the contributions of T-cell activation, endothelial damage, and inflammatory processes in promoting rejection. Biomarkers such as donor-derived cell-free DNA and microRNAs hold promise for early detection but have not yet achieved broad clinical implementation. The development of heart transplantation over time highlights gradual advances in results, but substantial shortcomings remain. This review synthesizes existing understanding and outlines key directions for subsequent investigation, highlighting the necessity for uniform methodologies and innovative approaches to reduce rejection and prolong graft survival.