Outcomes From Three Decades of Infant and Pediatric Heart Transplantation

Changes in waiting time, need for mechanical circulatory support and outcomes in paediatric heart transplant recipients

AIMS

Heart transplantation is a well-established treatment for end-stage heart failure in paediatric patients, demonstrating excellent long-term outcomes.

METHODS

This retrospective study analyses 35 years of data on 244 paediatric recipients (<18 years) at a single institution from 1986 to 2022. The analysis explores changes in diagnoses, survival, waiting times and mechanical circulatory support (MCS) over three decades (1991-2000, 2001-2010 and 2011-2020).

RESULTS

Survival outcomes significantly improved over the study period, with 1-year survival rates increasing from 79.3% (1991-2000) to 92.3% (2011-2020, P = 0.041). The median overall survival was 18.0 years, and median conditional survival to 1 year post-transplant was 20.9 years. Survival differences were noted among age groups, with infants under 1 year of age experiencing higher early mortality, and adolescents (aged 11-17 years) facing increased long-term risks, possibly linked to adult donor characteristics. Waiting times for heart transplantation increased, especially for younger age groups (0-5 and 6-10 years), reflecting the growing demand for donor organs. The use of MCS, including ventricular assist devices (VAD), surged, with 67% of recipients in the most recent decade receiving pre-transplant VAD support. Importantly, despite prolonged waiting times and increased VAD use, overall survival continued to be favourable.

CONCLUSIONS

Early and long-term results after paediatric heart transplantation have been continuously improving over the past decades. Despite an increased demand for donor organs and the growing reliance on VAD as bridge to transplantation, post-transplantation survival is not compromised.

Outcomes of heart transplantation in children with previously palliated hypoplastic left heart syndrome

OBJECTIVES

Paediatric heart transplantation in children who fail multistage palliation for hypoplastic left heart syndrome is associated with challenges related to immune, clinical or anatomic risk factors. We review current outcomes and risk factors for survival following heart transplantation in this challenging patient population.

METHODS

The United Network for Organ Sharing transplantation database was merged with Paediatric Health Information System database to identify children who received heart transplantation following prior palliation for hypoplastic left heart syndrome. Multivariable Cox analysis of outcomes and factors affecting survival was performed.

RESULTS

Our cohort included 849 children between 2009 and 2021. The median age was 1044 days (interquartile range 108-3535), and the median weight was 13 kg (interquartile range 7-26). Overall survival at 10 years following heart transplantation was 71%, with most of the death being perioperative. On multivariable analysis, risk factors for survival included Black race (hazard ratio = 1.630, P = 0.0253), blood type other than B (hazard ratio = 2.564, P = 0.0052) and male donor gender (hazard ratio = 1.367, P = 0.0483). Recipient age, the use of ventricular assist device or extracorporeal membrane oxygenation were not significantly associated with survival. Twenty-four patients underwent retransplantation, and 10-year freedom from retransplantation was 98%. Rejection before hospital discharge and within 1 year from transplantation was 20% and 24%, respectively, with infants having lower rejection rates.

CONCLUSIONS

Compared with existing literature, the number of children with prior hypoplastic left heart syndrome palliation who receive heart transplantation has increased in the current era. Survival following transplantation in this patient population is acceptable. Most of the death is perioperative. Efforts to properly support these patients before transplantation might decrease early mortality and improve overall survival.

Paediatric heart transplantation: life-saving but not yet a cure

In the 1980s, heart transplantation was the first successful treatment for infants born with hypoplastic left heart syndrome. Infants who have required heart transplantation benefit from immunologic "advantages," including long-term survival free from cardiac allograft vasculopathy. Currently ∼ 90% of children undergoing a heart transplant are reaching their first-year anniversary and the clinical practices of paediatric heart transplantation have dramatically improved. These successes are largely attributed to research sponsored by the Pediatric Heart Transplant Study Group, the International Society of Heart and Lung Transplantation and, more recently, the Non-profits Enduring Hearts and Additional Ventures. Despite these successes, the field is challenged to increase progress to achieve long-term survival into adulthood. The wait-list mortality, especially among infants, is unacceptably high often leading to palliative measures that can increase post-transplant mortality. Cardiac allograft vasculopathy remains a major cause for progressive graft loss of function and sudden death. The relative tolerance seen in immature recipients has not been translated to modifying older recipients' post-transplant outcomes. The modifiable cause(s) for the increased risks of transplantation in children of different ethnicities and races require definition. Addressing these challenges faces the reality that for-profit research favours funding adult recipients, with ∼ 10-fold greater numbers, and their more modest longevity goals. Advocacy for funding "incentives" such as the Orphan Drug rules in the United States and upholding principles of equity and inclusion are critical to addressing the challenges of paediatric heart transplant recipients worldwide.

Not all durations of preheart transplant mechanical ventilation portend inferior post-transplant survival in children

BACKGROUND

Mechanical ventilation prior to pediatric heart transplantation predicts inferior post-transplant survival, but the impact of ventilation duration on survival is unclear.

METHODS

Data from the United Network for Organ Sharing and Pediatric Health Information System were used to identify pediatric (<18 years) heart transplant recipients from 2003 to 2020. Patients ventilated pretransplant were first compared to no ventilation, then ventilation durations were compared across quartiles of ventilation (≤1 week, 8 days-5 weeks, >5 weeks).

RESULTS

At transplant, 11% (511/4506) of patients required ventilation. Ventilated patients were younger, had more congenital heart disease, more urgent listing-status, and greater rates of nephropathy, TPN-dependence, and inotrope and ECMO requirements (p < .001 for all). Post-transplant, previously ventilated patients experienced longer ventilation durations, ICU and hospital stays, and inferior survival (all p < .001). Hospital outcomes and survival worsened with longer pretransplant ventilation. One-year and overall survival were similar between the no-ventilation and ≤1 week groups (p = .703 & p = .433, respectively) but were significantly worse for ventilation durations >1 week (p < .001). On multivariable analysis, ventilation ≤1 week did not predict mortality (HR 0.98 [95% CI 0.85-1.43]), whereas ventilation >1 week did (HR: 1.18 [1.01-1.39]).

CONCLUSIONS

Longer pretransplant ventilation portends worse outcomes, although only ventilation >1 week predicts mortality. These findings can inform pretransplant prognostication.

Infants Who Require Total Parenteral Nutrition and Paralytics at Time of Heart Transplant Experience Inferior Post-Transplant Mortality

Background: Infants experience the worst one-year post-heart transplant (HTx) survival of any other pediatric group. Although mechanical ventilatory (MV) requirement at the time of transplant is an established predictor of post-transplant mortality, the impacts of commonly co-utilized support modalities such as total parenteral nutrition (TPN)-dependence and paralytics are understudied. Methods: All infant HTx recipients from 2003 to 2020 in both the United Network for Organ Sharing and Pediatric Health Information System databases were identified (n = 1344) and categorized depending upon support requirement at the time of transplant—none (59%), MV-only (10%), MV + Paralytics (2%), TPN-dependence-only (15%), MV + TPN (10%), and MV + Paralytics + TPN (4%). The primary study aim was to characterize the impact of TPN-dependence and paralytics on one-year post-transplant survival (PTS). Results: Compared to no-support, supported infants were generally at higher risk and more ill at transplant, with greater rates of congenital heart disease, renal and hepatic dysfunctions, and inotrope requirements. Post-transplant hospital outcomes were inferior among supported patients; all support groups experienced longer post-transplant MV, intensive care unit, and hospital lengths of stay (all P < .05 vs no-support). Upon multivariable analysis, each support modality independently predicted 1-year mortality (MV vs no-MV: 1.54 [1.10-2.14]; MV + Paralytics vs neither: 2.02 [1.25-3.27]; TPN vs no-TPN: 1.53 [1.10-2.13]; P < .01 for all), whereas no-support was protective (HR 0.66 [95% CI 0.48-0.91]). Conclusions: Infants who require paralytics and/or who are TPN-dependent at the time of HTx experience worse one-year PTS. Such knowledge can assist in risk-stratification, and the identification of patients who would benefit from pretransplant optimization.