Pediatric Heart Transplant Candidates Research Articles

(112) - Improved Equity in 1A, but Not 1B, Status Exceptions for Pediatric Heart Transplant Candidates with Pediatric Specific Review Board and Exception Guidance

(112) - Improved Equity in 1A, but Not 1B, Status Exceptions for Pediatric Heart Transplant Candidates with Pediatric Specific Review Board and Exception Guidance

(73) - Favorable Use of Daratumumab in Highly Sensitized Pediatric Heart Transplant Candidates and Recipients

(73) - Favorable Use of Daratumumab in Highly Sensitized Pediatric Heart Transplant Candidates and Recipients

Supplemental nutrition, feeding disorders, and renourishment in pediatric heart failure through transplantation.

Tube feeds are used commonly in children listed for heart transplant; however, rates of renourishment and development of feeding disorders are not sufficiently characterized. Retrospective review of pediatric heart transplant recipients from January 1, 2014, to January 3, 2021. Demographics, anthropometric, and nutritional data were collected from heart transplant listing through 3 years post-transplant. Renourishment rates, presence of a feeding disorder, and need for a gastric feeding tube were analyzed. Multivariable analysis was conducted to identify risks for poor nutritional outcomes. Of 104 patients, 35 (34%) and 36 (35%) were malnourished at heart transplant listing and transplant, respectively, persisting in 21/91 (23%) 1 year postheart transplant. Forty (38%) received tube feeds at listing, 42 (40%) at heart transplant, and 18/90 (20%) 1 year post-transplant. Rates of feeding disorders fell from 23% at transplantation to 10% 1 year post-transplant. Feeding disorders were associated with younger age at heart transplant (p < .001) and congenital heart disease (p = .03). Forty-six percent of infants required a gastric feeding tube. Renourishment occurred in 20% during listing and was associated with ventricular assist device support (p = .03) and noncalorically dense feeds (p = .03). Malnutrition at transplant was associated with inferior post-transplant survival (6/36 (17%) vs. 2/68 (3%); p = .02). Malnourishment requiring tube feeds is common in pediatric heart transplant candidates; however, most patients who eventually survive to transplant remain malnourished at time of transplantation and 1 year later. While some children develop feeding disorders, they generally resolve by 1 year post-transplant.

Pediatric risk to orthotopic heart transplant (PRO) score: Insights from United Network for Organ Sharing (UNOS) waitlist mortality findings.

Pediatric heart transplant candidates on the waitlist have the highest mortality rate among all solid organ transplants. A risk score incorporating a candidate's individual risk factors may better predict mortality on the waitlist and optimize organ allocation to the sickest of those awaiting transplant. Using the United Network for Organ Sharing (UNOS) database, we evaluated a total of 5542 patients aged 0-18 years old on the waitlist for a single, first time, heart transplant from January 2010 to June 2019. We performed a univariate analysis on two-thirds (N = 3705) of these patients to derive the factors most associated with waitlist mortality or delisting secondary to deterioration within 1 year. Those with a p <0.2 underwent a multivariate analysis and the resulting factors were used to build a prediction model using the Fine-Grey model analysis. This predictive scoring model was then validated on the remaining one-third of the patients (N = 1852). The Pediatric Risk to OHT (PRO) scoring model utilizes the following unique patient variables: blood type, diagnosis of congenital heart disease, weight, presence of ventilator support, presence of inotropic support, extracorporeal membrane oxygenation (ecmo) status, creatinine level, and region. A higher score indicates an increased risk of mortality. The PRO score had a predictive strength of 0.762 as measured by area under the ROC curve at 1 year. The PRO score is an improved predictive model with the potential to better assess mortality for patients awaiting heart transplant.

CARD15: Parent Perceptions of Ex-Situ Heart Perfusion

Introduction: Pediatric heart transplant (HTx) candidates continue to have high waitlist mortality due to donor availability. Ex-situ heart perfusion (ESHP) has the potential to increase the donor pool, yet has been used sparingly in pediatrics due to size restrictions of the current technology. Previous work has shown that for ESHP to be accepted by pediatric healthcare providers (HCP), the risks to the donor heart and the costs need to be better understood and that rigorous research and implementation oversight is essential. Perspectives from caregivers about ESHP has not been assessed and forms the basis of this qualitative study. Methods: Virtual, semi-structured interviews were conducted with caregivers of children who are awaiting or received HTx. Data were analyzed using qualitative content analysis. Results: Twelve participants from 2 countries participated in this study. Awareness about and understanding of ESHP varied among participants from complete unawareness to understanding specifics. Independent of their awareness, all purported that it was an excellent and innovative technology, and supported ESHP implementation in pediatrics. No ethical issues or concerns about the use were identified that differed from other medical technologies, although participants did state that understanding the length of time the heart can be mounted and risks to donor and recipient were important. Participants expressed various views on how to approach parents regarding ESHP. Overall, most participants stated that the consent processes should be like other medical procedure and some commented that deferred or waived consent would be acceptable, especially if ESHP became part of routine clinical practice. Even if consent was waived, participants agreed that the use of ESHP should be disclosed just like other information is disclosed about the donor heart and that introduction of ESHP should come early in the HTx journey. Conclusion: Families are supportive of the use of ESHP. Like HCPs, they endorse the need to understand the potential risks and that information should be presented early in the transplant process.

Racial and socioeconomic disparities in status exceptions for pediatric heart transplant candidates under the current U.S. Pediatric Heart Allocation Policy

The 2016 revision of the US Pediatric Heart Allocation Policy developed stringent rules for priority status creating impetus for clinicians to seek status exceptions. We hypothesized there may be differential status exceptions based on race and socioeconomic status (SES) contributing to disparities in waitlist outcomes. The Scientific Registry for Transplant Recipients was queried for children listed for heart transplant from 2012 to 2020. Waitlist status & mortality with regards to race and neighborhood SES were stratified by listing before (Era 1) or after (Era 2) the policy change. The use of both 1A and 1B exceptions (E) increased in Era 2. In Era 1, there was no association between patient race or neighborhood SES on use of 1A(E) or 1B(E) when controlling for age and diagnosis. In Era 2, neither race nor neighborhood SES were associated with 1A(E), but both were associated with 1B(E): non-Hispanic (NH) Black children and those from low- and middle-SES neighborhoods were significantly less likely to be listed 1B(E). In Era 1, there were no significant differences in waitlist mortality based on race at any waitlist status; in Era 2, NH Black children had higher waitlist mortality when initially listed 1B or 2. Since the 2016 policy change, racial disparities in waitlist mortality have worsened among children initially listed with lower priority status. Unequal use of 1B exceptions, which lower waitlist mortality, may explain some of these disparities. Recently implemented standardized pediatric exception guidance has the potential to improve equity.

(1136) Genetic Testing Provides Anticipatory Guidance in Pediatric Heart Transplant Candidates

(1136) Genetic Testing Provides Anticipatory Guidance in Pediatric Heart Transplant Candidates

It Takes Two: Outcomes of Pediatric Heart Transplant Candidates With Renal Dysfunction

Associated Factors and Impact of Persistent Renal Dysfunction in Pediatric Heart TransplantationThe Annals of Thoracic SurgeryPreviewWe evaluated the impact of significant renal dysfunction (SRD) on listing and pediatric heart transplantation (PHT) outcomes. Full-Text PDF

Worsening racial disparity in waitlist mortality for pediatric heart transplant candidates since the 2016 Pediatric Heart Allocation Policy revision.

The US Pediatric Heart Allocation Policy (PHAP) was revised in March 2016, with the goal of reducing waitlist mortality. We evaluated the hypothesis that these changes, which increased status exceptions, have worsened racial disparities in waitlist outcomes. Children in the Pediatric Heart Transplant Study database listed for first heart transplant from January 2012 - June 2020 were included and stratified by listing before (Era 1) or after (Era 2) the PHAP revision. A total of 4,089 children were listed during the study period. Compared with white children (n= 2648), non-white children (n= 1441) were more likely to have an underlying diagnosis of cardiomyopathy in both eras. Waitlist mortality was similar in white and non-white children in Era 1, but comparatively worse for non-white children in Era 2. In multivariable analysis controlling for diagnosis, age, and severity markers, non-white children had a significantly higher waitlist mortality only in Era 2 (Era 1: sHR 1.22 [95%CI 0.90-1.66] vs. Era 2: sHR 1.57 [95%CI 1.17-2.10]). Widening racial disparities in waitlist mortality may be an unintended consequence of the 2016 PHAP revision. Additional analyses may inform the degree to which this policy vs. unrelated changes in care differentially contribute to these disparities.

Facilitators and Barriers of Ex Situ Heart Perfusion (ESHP) in Pediatric Donation

Purpose Despite medical advances, pediatric heart transplant (HTx) candidates are at significant risk for morbidity and mortality. Ex Situ Heart Perfusion (ESHP) is a method for continuous perfusion of the donor heart, allowing for extended out-of-body time and functional assessment of the organ. Currently available devices are targeted to adults and have been used in the context of neurological and circulatory determination of death. Pediatric-specific devices are in development, but before adoption, knowledge of stakeholder attitudes towards ESHP is needed. The aim of this study was to explore pediatric HTx stakeholders’ understanding and perspectives of ESHP. Methods A virtual focus group study was conducted international pediatric HTx stakeholders. Data was analyzed using qualitative content analysis. Results There were 17 participants from 12 institutions representing 3 countries. Findings were organized under the topics of: general knowledge, indications, risks, adoption/barriers, and pediatric-specific considerations. Knowledge ranged from limited grasp of the technology to first-hand experience in clinical practice. Discussions encircled the current use of ESHP in adult-sized HTx candidates, and potential future uses in infants and young children. In all focus groups, it was discussed that risks need to be considered regarding ESHP itself, including the potential of damaging the donor heart, subjecting recipients to unquantified risks, and potential adverse impacts on pediatric HTx programs if poor outcomes occur. Concerns surrounding the material costs and human resources associated with ESHP were also discussed. While all discussions highlighted the need for pediatric ESHP devices, participants emphasized the need for rigorous research and implementation oversight of ESHP to navigate ethical issues, program administration, and support best practices in the context of technological innovation. Conclusion For stakeholders to become adopters of ESHP, they must understand the goals, benefits, and risks. This project represents the first step in the adoption of new technology, and the knowledge gained will form the basis for future education, clinical trial design, and rollout of pediatric ESHP technologies. Despite medical advances, pediatric heart transplant (HTx) candidates are at significant risk for morbidity and mortality. Ex Situ Heart Perfusion (ESHP) is a method for continuous perfusion of the donor heart, allowing for extended out-of-body time and functional assessment of the organ. Currently available devices are targeted to adults and have been used in the context of neurological and circulatory determination of death. Pediatric-specific devices are in development, but before adoption, knowledge of stakeholder attitudes towards ESHP is needed. The aim of this study was to explore pediatric HTx stakeholders’ understanding and perspectives of ESHP. A virtual focus group study was conducted international pediatric HTx stakeholders. Data was analyzed using qualitative content analysis. There were 17 participants from 12 institutions representing 3 countries. Findings were organized under the topics of: general knowledge, indications, risks, adoption/barriers, and pediatric-specific considerations. Knowledge ranged from limited grasp of the technology to first-hand experience in clinical practice. Discussions encircled the current use of ESHP in adult-sized HTx candidates, and potential future uses in infants and young children. In all focus groups, it was discussed that risks need to be considered regarding ESHP itself, including the potential of damaging the donor heart, subjecting recipients to unquantified risks, and potential adverse impacts on pediatric HTx programs if poor outcomes occur. Concerns surrounding the material costs and human resources associated with ESHP were also discussed. While all discussions highlighted the need for pediatric ESHP devices, participants emphasized the need for rigorous research and implementation oversight of ESHP to navigate ethical issues, program administration, and support best practices in the context of technological innovation. For stakeholders to become adopters of ESHP, they must understand the goals, benefits, and risks. This project represents the first step in the adoption of new technology, and the knowledge gained will form the basis for future education, clinical trial design, and rollout of pediatric ESHP technologies.

Impact of the 2018 Adult Heart Allocation Change on Pediatric Donor Offers and Waitlist Outcomes

<h3>Purpose</h3> On October 18, 2018, UNOS made important revisions to the adult allocation system for heart transplant (HT). Although the revisions primarily affect the prioritization of adult HT candidates, it could impact pediatric candidates indirectly as adult candidates listed Status 1 or 2 take priority over pediatric Status 1B and 2 candidates. We sought to determine if there was any effect on donor offers, declines and waitlist outcomes for pediatric candidates in light of the adult allocation change. <h3>Methods</h3> All children <18 listed for HT within a 2-year period before and after the adult allocation revision was implemented were identified using OPTN data. Match-run analysis was also performed to examine the offer and decline rates. The primary endpoints were candidate transplantation and mortality rates. <h3>Results</h3> A total of 2,397 children met the study inclusion criteria, including 1,295 children listed before and 1,102 children listed after the adult policy change. The two cohorts were similar with respect to age, weight, cardiac diagnosis, ECMO, ventilator, VAD use, and insurance status. Nationwide offers to pediatric 1A candidates increased 34% per day, though center rejection of offers also rose a similar amount (41%). Pediatric candidates listed Status 1B and 2 also received more offers with a similar rise in center rejections, though the increases were smaller than for 1A candidates. Transplantation and mortality within 30-, 60- and 90-days did not change for 1A/1B candidates perhaps owing to the concomitant rise in center rejections of offers. There was a modest but significant decline in the likelihood of 30- and 60-day transplantation for patients listed at Status 2 following the change, though the likelihood of 90-day transplantation was comparable. <h3>Conclusion</h3> The 2018 changes to the adult allocation system have, if anything, resulted in an increased flow of donor offers to pediatric candidates, however transplantation rates for children listed 1A and 1B appear similar before and after the change, partly because the rise in offers was associated with a rise in offer rejections. For pediatric Status 2 candidates, transplantation was slightly lower at 30- and 60-days, but comparable at 90 days. More work is needed to reduce offer rejections to increase the transplantation rate for pediatric HT candidates.

Pediatric heart transplant waiting times in the United States since the 2016 allocation policy change

We describe waiting times for pediatric heart transplant (HT) candidates after the 2016 revision to the US allocation policy. The OPTN database was queried for pediatric HT candidates listed between 7/2016 and 4/2019. Of the 1789 included candidates, 65% underwent HT, 14% died/deteriorated, 8% were removed for improvement, and 13% were still waiting at the end of follow-up. Most candidates were status 1A at HT (81%). Median wait times differ substantially by listing status, blood type, and recipient weight. The likelihood of HT was lower in candidates <25kg and in those with blood type O; The <25kg, blood type O subgroup experiences longer wait times and higher wait list mortality. For status 1A candidates, median wait times were 108days (≤25kg, blood type O), 80days (≤25kg, non-O), 47days (>25kg, O), and 24days (>25kg, non-O). We found that centers with more selective organ acceptance practices, based on a lower median Pediatric Heart Donor Assessment Tool (PH-DAT) score for completed transplants, experience longer status 1A wait times for their listed patients. These data can be used to counsel families and to select appropriate advanced heart failure therapies to support patients to transplant.

Heart-kidney listing is better than isolated heart listing for pediatric heart transplant candidates with significant renal insufficiency

ObjectivesSignificant renal insufficiency is identified as a risk factor for post-transplantation mortality in pediatric heart transplant recipients. This study evaluates simultaneous heart-kidney transplantation listing outcomes compared with heart transplant for pediatric candidates with significant renal insufficiency. MethodsThe United Network for Organ Sharing registry was searched for patients (January 1987 to March 2020) who were simultaneously listed for a heart-kidney transplantation or for heart transplant with significant renal insufficiency at the time of listing. Significant renal insufficiency was defined as needing dialysis or having a low estimated glomerular filtration rate (<40 mL/min). Survival was calculated using Kaplan–Meier analysis. ResultsA total of 427 cases were identified; 109 were listed for heart-kidney transplantation, and 318 were listed for heart transplant alone. Median time on the waitlist was 101 days (interquartile range, 28-238) for heart-kidney transplantation listings compared with 39 days (14-86) and 23.5 days (6-51) for heart transplant recipients with a low estimated glomerular filtration rate (P = .002) or on dialysis (P < .001), respectively. Of all heart-kidney transplantation listings, 66% (n = 71) received a transplant compared with 54% (n = 173) of heart transplantation with significant renal insufficiency (P = .005) with a mean survival of 14.6 years (12.7-16.4 years) for heart transplant without significant renal insufficiency at transplantation and 7.6 years (5.4-9.9 years) for heart transplant with significant renal insufficiency at transplantation. At 1 year after listing, 69% of heart-kidney transplantation listed recipients were alive, compared with 51% of heart transplant listed recipients (P = .029). Heart-kidney transplantation recipients had better 1-year post-transplantation survival (86%) than heart transplantation with significant renal insufficiency at transplant (66%) (P = .001). There was no significant difference in the 1- and 5-year survivals of those undergoing heart transplantation listed with significant renal insufficiency but no significant renal insufficiency at the time of transplant (89% and 78%) and heart-kidney transplantation recipients (86% and 81%; P = .436). ConclusionsPediatric candidates with significant renal insufficiency listed for heart-kidney transplantation have superior waitlist and post-transplantation outcomes compared with those listed for heart transplant alone. Patients with significant renal insufficiency should be listed for heart-kidney transplantation, however; if their renal function improves significantly, heart transplant alone appears judicious.

Children who stroke on VAD support: When is it safe to transplant and what are their outcomes?

Ventricular assist devices (VADs) increase waitlist survival, yet the risk of stroke remains notable. The purpose of this study was to analyze how strokes on VAD support impact post-transplant (post-Tx) outcomes in children. About 520 pediatric (<18years) heart transplant candidates listed from January 2011 to April 2018 with a VAD implant date were matched between the United Network of Organ Sharing and Pediatric Health Information System databases. Patients were divided into pre-Tx Stroke and No Stroke cohorts. About 81% of the 520 patients were transplanted; 28% (n=146) had a pre-Tx Stroke; and 59% (n=89) of the Stroke patients were transplanted at a median of 57 (IQR 17-102) days from stroke. Significantly more No Stroke cohort (90%) were transplanted (p<0.001). There was no difference in post-Tx survival between the Stroke and No Stroke cohorts (p=0.440). Time between stroke and transplant for patients who died within 1year of transplant was 32.0days (median) compared to 60.5days for those alive >1year (p=0.18). Regarding patients in whom time from stroke to transplant was more than 60days, one-year survival of Stroke vs. No Stroke patients was 96% vs. 95% (p=0.811), respectively. Patients with stroke during VAD support, once transplanted, enjoy similar survival compared to No Stroke patients. We hypothesize that allowing Stroke patients more time to recover could improve post-Tx outcomes. Unfortunately, the ideal duration of time between stroke and safe transplantation could not be determined and will require more detailed and larger studies in the future.

Early report from the Pediatric Heart Transplant Society on COVID-19 infections in pediatric heart transplant candidates and recipients

BackgroundReports focused on adult heart transplant (HTx) recipients with COVID-19 suggest an increased risk of severe disease, however; it is unclear if this holds true for pediatric HTx patients, given the typically milder course of illness in children in general with COVID-19. We sought to rapidly implement a system for multi-center data collection on pediatric HTx candidates and recipients, with the aim of describing the patient population and infection related outcomes.MethodsThe Pediatric Heart Transplant Society (PHTS) is a multi-center collaboration that seeks to improve the outcomes of children who are listed and undergo HTx. The society consists of pediatric HTx centers in North America (n = 53), UK (n = 2), and Brazil (n = 1). In response to the pandemic, PHTS developed a web-based platform to collect COVID-19 specific data on pediatric HTx candidates and recipients. Non-PHTS centers were also invited to submit data. Data fields included pre-and post-HTx patient characteristics, presumed versus documented infection, need for hospitalization (including ICU and ventilator use), treatments administered, and 30-day outcome (resolution, death, sequelae, and or unresolved)ResultsData collection was initiated on 4/30/20. As of 03/15/21 there were 225 patients [19 pre-HTx and 206 post-HTx, median age 14 years (IQR 7, 18)] reported from 41 centers. Hospitalization occurred in 42% (n = 8) of the pre-HTx and 21% (n=43) of the post-HTx patients. Among the patients listed for HTx, 21% (n = 4) required ICU and 10.5% (n = 2) were mechanically ventilated. Among post-HTx patients, 7% (n = 14) required ICU and 1% (n = 3) were mechanically ventilated. At 30 days, the majority of patients had resolution of symptoms (94.7% pre-HTx, 95.6% post-HTx). One death was reported in a post-HTx patient prior to 30 days from onset of COVID-19 illness.ConclusionsThese data demonstrate the ability to rapidly adapt the PHTS data collection infrastructure in response to a novel infection and represent the first known multi-center report of characteristics and early outcomes for patients listed and following pediatric HTx with COVID-19. Hospitalization appears to be more common for both candidates and recipients due to COVID-19 than for the general pediatric population though stays were short and mortality minimal.

Abstract 10540: Worsening Racial Disparity in Waitlist Mortality for Pediatric Heart Transplant Candidates Since the 2016 Pediatric Heart Allocation Policy Revision

Introduction: The US Pediatric Heart Allocation Policy was recently revised with the goal of lowering waitlist mortality. Effective March 2016, these rules significantly changed the requirements for priority status. We evaluated the hypothesis that this change, which has led to an increase in status exceptions, has worsened known racial disparities in waitlist outcomes. Methods: Children in the Pediatric Heart Transplant Study database listed at a US center from January 2012 - June 2020 were included and stratified by listing before (Era 1) or after (Era 2) allocation policy change on March 22, 2016. Competing risk survival analysis was performed to evaluate endpoint of death or deterioration on the waitlist with transplant treated as a competing risk. Results: Compared with white children (n=2,648), non-white children (n=1,441) were more likely to have an underlying diagnosis of cardiomyopathy (49% vs. 39%, p&lt;0.001), be currently hospitalized (81% vs. 71%, p=0.007) and supported with a ventricular assist device (VAD) (12% vs 9%, p=0.005) at the time of listing. Waitlist mortality was similar in white and non-white children in Era 1, but worse for non-white children compared to white children in Era 2 (Figure). In multivariable analysis controlling for diagnosis, age and severity markers, non-white children had a significantly higher waitlist mortality only if listed after the policy change (Era 1: sHR 1.18 [95%CI 0.88 - 1.59] vs. Era 2: sHR 1.52 [95%CI 1.14 - 2.02]). Hispanic ethnicity was not associated with waitlist mortality in either period when controlling for other risk factors. Conclusions: Widening racial disparities in waitlist mortality may be an unintended consequence of the 2016 Pediatric Heart Allocation Policy revision. Additional analyses may help the transplant community understand the degree to which this policy (i.e. prioritized listing status and exceptions) vs. unrelated changes in care differentially contribute to these disparities.

Early Report on COVID-19 Infections in Pediatric Heart Transplant Recipients and Candidates

PurposeReports focused on adult heart transplant (HT) recipients with COVID-19 suggest an increased risk of severe disease. It is unclear if this holds true for pediatric HT patients, given the reported milder course of illness in children in general with COVID-19. We sought to rapidly implement a system for multi-center data collection on pediatric HT recipients and candidates, with the aim of describing the patient population and infection related outcomes.MethodsThe Pediatric Heart Transplant Society (PHTS) is a multi-center collaboration whose main goal is to improve the outcomes of children who are listed and undergo HT. The society consists of pediatric HT centers in North America (n=53), UK (n=2), and Brazil (n=1). In response to the pandemic, PHTS developed a web-based platform to collect COVID-19 specific data in pediatric HT candidates and recipients. Non-PHTS centers were also invited to submit data. Data fields included pre-and post-HT patient characteristics, presumed vs. documented infection, need for hospitalization (including ICU and ventilator use), treatments administered, and 30-day outcome (death, resolution, sequelae, ongoing treatment).ResultsData collection was initiated on 4/30/20. As of 9/28/20, there were 72 patients (7 pre-HT and 65 post-HT, median age 13 years) reported from 27 centers. Of these, 67 were PCR+ by nasal swab and 5 were presumed positive. Complete data with 30-day follow-up was available for 60 patients (7 pre and 53 post HTx). Hospitalization was common and occurred in 71% of the pre-HT and 32% of the post HTx patients. Of the pre-Tx patients, 43% required ICU and 14% were ventilated. In the post HTx group, 13% required ICU and 4% were ventilated. At 30 days a majority of pre-Tx had resolution of symptoms (n=6/7). Among post HTx patients, resolution occurred in 87%% (46/53) with 1 death at 30 days.ConclusionThe PHTS remains the most robust source of data on pediatric HT and this effort shows the adaptability of the registry. Although likely limited by reporting bias, these data represent the first known report of characteristics and early outcomes for pediatric HT candidates and recipients with COVID-19. As data collection continues, we aim to better understand the characteristics of patients with more severe disease in order to improve risk characterization and decrease the knowledge gap that currently exists in this unique population.

Wait Times in Pediatric Heart Transplant Candidates: Impact of Size and Blood Type Following the 2016 Allocation Policy Revision

Purpose To describe wait times for pediatric heart transplant (HT) candidates following new allocation policies in 2016. Methods The OPTN database was queried for pediatric HT candidates listed for HT between 7/2016 and 4/2019. Wait times were analyzed by listing status (1A, 1B, 2), blood type, and recipient weight. Candidates were analyzed by days spent at each listing status, classified as transplanted only in their final listing status, and censored in the analysis for any other statuses in which they spent time listed. Wait list outcomes were analyzed using a competing risk analysis and a proportional subdistribution hazards regression model was used to compare associations between predictors and outcomes. Results The study included 1,789 candidates listed for HT under the new allocation system. 65% underwent HT, 14% died or were removed for clinical deterioration, 8% were removed for other reasons including clinical improvement, and 13% were still waiting at the end of the study period. The majority of children were listed as status 1A at the time of HT (81%), while 16% were listed as status 1B and 2.6% were status 2 at the time of HT. Candidates Conclusion Wait times for pediatric HT candidates are highly variable, with listing status, size, and blood type contributing to wait time and likelihood of HT. Children less than 25 kg, particularly those who are blood type O, experience longer wait times and higher wait list mortality. Advanced heart failure therapies should be selected with these longer wait times in mind.

Efficacy and Safety of Desensitization Therapy in Pediatric Heart Transplant Candidates

<h3>Purpose</h3> Allosensitization to human leukocyte antigen (HLA) in pediatric heart transplant candidates is associated with higher waitlist, post-transplantation mortality and antibody mediated rejection. As limited safety/efficacy data exist on pre-transplant desensitization regimen, we reviewed our institution's experience. <h3>Methods</h3> We reviewed the medical records of 12 highly sensitized (average cPRA = 68%) pediatric heart transplant candidates who underwent desensitization therapy at the University of Virginia Hospital between 2014 and 2020. The following data were collected: individual immunosuppression regimen, pre and post desensitization levels of antibody burden, documented side effects, and incidence of antibody mediated rejection. <h3>Results</h3> The majority of patients received an oral immunosuppressive regimen of Prednisone (0.3 mg/kg/day to max dose of 12.5 mg) and an antimetabolite (Cellcept 60 mg/kg/dose q12 up to 1,000 mg q12 or Imuran 1-2 mg/kg/day) followed by a single infusion of Rituximab (375 mg/m2) and monthly intravenous immunoglobulin (IVIG 2 g/kg) infusions; plasmapheresis was used in one patient and Bortezomib was used in two. cPRA decreased by an average of nearly 20% after an average of 17.5 weeks (Table 1). HLA I antibodies were more susceptible to desensitization than HLA II antibodies (60% vs 36% average antibody reduction, respectively). Immunosuppression medications were well tolerated with only one patient requiring Rituximab discontinuation due to hypotension, tachycardia and respiratory distress. There were no cases of antibody mediated rejection in those patients who underwent transplantation. <h3>Conclusion</h3> In our cohort, B-cell/ antibody targeted therapies were safe and effective in improving allosensitization and allowing for successful transplantation, though HLA II antibodies were more resistant to therapy. Larger scale studies are needed.

Functional Status as a Predictor of Pediatric Heart Transplant Outcomes

Purpose Functional status at listing predicts waitlist survival in adult heart transplant candidates including those on mechanical circulatory support. This has not been studied in pediatric heart transplantation although it is an independent predictor of outcomes in pediatric liver transplantation. We aimed to determine the association of: 1) functional status at listing with waitlist and post-transplant outcomes, and 2) functional status at transplant with post-transplant outcomes in pediatric heart transplant candidates. Methods Retrospective registry study of 5754 patients ≤18 years old listed for heart transplant between 1995 and 2019 with Lansky/Karnofsky Play Performance Scale (LPPS) scores in the UNOS database. Standard statistical methods were used to assess relationships of LPPS scores at listing and transplant with waitlist and post-transplant outcomes. A positive waitlist outcome was defined as transplantation, removal from waitlist due to clinical improvement, or remaining on waitlist. Results At listing, 1463 patients had the ability to carry out normal activities (LPPS 80-100), 2338 had mild-moderate restriction in functional status (LPPS 50-70), and 1953 had moderate-severe restriction (LPPS 10-40). Normal activity and mild-moderate restriction at listing were associated with a higher positive waitlist outcome rate compared with moderate-severe restriction (90% vs 80%, p Conclusion Candidate functional status is associated with waitlist as well as post-transplant outcomes. Improvement in functional status between listing and transplant is associated with better outcomes 1-year post-transplant. These data suggest that interventions targeting functional impairment (e.g. physical rehabilitation) have the potential to improve pediatric heart transplant outcomes.