ABO-incompatible Heart Transplantation (HTX) in Infants and Newborns could Decrease the Death Risk on Waiting List: “A Meta-Analysis”

Introduction: Due to an increasing waiting time for available donor organs in pediatric heart transplantation (pHTx) ABO-incompatible HTx (HTxi) may be a satisfying option and probably an unpreventable one. There is an immunological window of tolerance during the human embryonic development which persists into the time of infancy. It has the potential of developing natural antibodies to ABO-antigens. This process plays a significant role in ABOi organ transplantation and could maintain long-term tolerance to a certain degree in the setting of HTxi.

Methods: This systematic review and meta-analyses aims at providing an overview of the reported outcome of infants and small children with end stage heart failure after undergoing a HTx. MEDLINE, Embase, PubMed, and Web of Science were searched for original research studies. A systematic literature search for publications reporting the outcome after pHTx published between 2001 and 2017 was conducted. Studies written in English with a study size of more than 10 patients were included. The primary outcome was mortality at HTx-listing and one year after ABO-compatible HTx (HTxc) or HTxi. Exploratory data analysis of four studies was analyzed. Two types of model (FE model = fixed effect model, RE model = random effect model) were represented. Primary outcome measure was all-cause mortality or delisting on the HTx list.

Results: Total mortality on HTx list in all groups was: I2 = 89.9%, 95% CI = 64%, 99.3%. Delisted from HTx list because of recovering or worsening of clinical status before HTx: I2 = 72.6%, 95% CI = 16.8%, 97.5%. HTxc: I2 = 99%, 95%CI = 97.3%, 99.8%. 43% of the patients were transplanted HTxc in average with a 95% confidence interval of 0.41, 0.45. HTxi showed: I2 = 99%, 95%CI = 99.1%, 99.9%. 12% of the patients were transplanted with an HTxi with a 95% confidence interval in average of 0.11, 0.14. 12 months survival after HTx was: I2 = 87.5%, 95%CI = 56.1%, 99.1%. 86% of the patients survived 12 months after HTx in average with a 95% confidence interval of 0.84, 0.88.

Conclusion: HTxi is a good option with similar results compared with HTxc in infants. It might avoid the long waiting time and minimizes the risk of death on the waiting list. However, long-term results are yet to be determined, as well as complications and risks. Aspects such as renal function, bacterial-, viral- and fungal-infection, graft vasculopathy, the risk for malignancy and chronic rejection after HTxi remain to be examined closely.

No conflict of interest has been declared by the author(s).