The Fourth Congress of the Turkish Transplantation Society

Liver Transplantation Across the ABO Barrier: The Role of Plasmapheresis

The initial experience with ABO incompatible (ABOi) orthotopic liver transplantations (OLTs) was dismal. In the current study, we investigated whether ABOi pediatric OLTs could achieve acceptable patient outcomes. The option for ABOi transplantation is vital because critically ill children have limited access to donor liver allografts.

Kaplan-Meier and multivariate Cox analysis was performed on data collected from 13,179 pediatric OLT recipients in the United Network for Organ Sharing database, including 540 ABOi recipients. We also analyzed 18 pediatric recipients of ABOi OLTs at Texas Children's Hospital. Recipients were divided into 2 groups: transplanted between 1987 to 2002 (remote era) and 2002 to 2013 (modern era).

Analysis revealed 4 main points. First, there was a significant (p < 0.01) improvement in ABOi OLT survival in the modern era. Second, threshold analysis revealed superior outcomes (p < 0.01) for OLT recipients younger than 2 years of age. Third, survival outcomes for ABOi and ABO-identical OLTs were the same for recipients younger than 2 years: ABOi was 91.8% (1 year) and 88.4% (5 year), and ABO identical was 91.5% (1 year) and 86.7% (5 year) (p = 0.94). Lastly, we found identical OLT results when analyzing our own institutional experience. To date, there has been a 92.9% survival rate in the modern era compared with 75% in the remote era. All recipients younger than 2 years (n = 9) are still alive, compared with 78% of those older than 2 years.

This analysis revealed a significant improvement in the survival of ABOi liver transplant recipients in the modern era. Importantly, ABOi liver transplantation can be performed in recipients younger than 2 years of age with equivalent outcomes compared with ABO-identical recipients.

ABO-incompatible heart transplantation, traditionally contraindicated because of the risk of hyperacute rejection, has been used selectively in recent years. Infants have limited production of isohemagglutinins, which may lower the risk of hyperacute rejection. A large national database was used to analyze the effect of ABO incompatibility on outcomes after heart transplantation in infants.

Heart transplant recipients aged younger than 1 year reported to the United Network for Organ Sharing from 1999 to 2007 were divided according to donor-recipient ABO incompatibility or compatibility. Outcomes included Kaplan-Meier survival and hyperacute rejection. Propensity-adjusted Cox regression modeling was used to identify predictors of mortality.

Of 591 infants that underwent heart transplantation, 35 (6%) received allografts from ABO-incompatible donors. ABO-incompatible recipients trended toward more congenital heart disease (71% vs 66%; p = 0.06) and were less likely to have dilated cardiomyopathy (11% vs 29%; p = 0.02). One ABO-incompatible infant had hyperacute rejection requiring retransplantation. No ABO-incompatible infant and 2 ABO-compatible infants died from hyperacute rejection. Survival was similar at 3 years. Propensity-adjusted Cox regression analysis demonstrated that ABO-incompatibility did not predict mortality (hazard ratio, 3.61; 95% confidence interval, 0.26–49.0; p = 0.33).

ABO-incompatible heart transplantation can be performed safely in infants without greater incidence of hyperacute rejection. ABO-incompatible heart transplantation should be strongly considered in infants to maximize donor organ utilization and reduce waiting-list mortality.

Recent data suggest that ABO blood group-incompatible donor hearts are immunologically well tolerated in infants undergoing transplantation.

Competing-risks methodology was used to assess outcomes after listing and the impact of a strategy to accept heart grafts from any blood group donor for infants less than 18 months of age.

From 1992 to 2002, there were 91 listing episodes in 84 patients (including 20 fetuses; 50% were male and 63% had congenital heart disease). Beginning in 1995, a strategy to accept ABO-incompatible organs was adopted. Competing-risks analysis showed that after 20 months 60% underwent transplantation, 18% died, and less than 1% were still listed; the remaining 21% were de-listed because of a change of surgical strategy (9%), improved clinical condition (8%), and deterioration to ineligibility (4%). Risk factors for transplantation included only a strategy to accept ABO-incompatible organs (P <.001). Risk factors for death included failure to accept ABO-incompatible organs (P =.002) and Canadian listing status 3 (P =.085) or 4 (P <.001). Multivariable parametric models were used to create competing risk predictions for outcomes specific to status and ABO-incompatible strategy. Higher status resulted in greater mortality regardless of strategy, although for any status, more patients underwent transplantation and fewer died using a strategy to accept ABO-incompatible organs. Parametric modeling of time-related freedom from death or retransplantation demonstrated no significant difference at 4 years posttransplantation (P =.78) for ABO-incompatible (74%) versus ABO-compatible transplants (72%).

A strategy to accept ABO-incompatible donor hearts for infant transplantation significantly improves the likelihood of transplantation and reduces waiting list mortality while not adversely altering outcomes after transplantation.