Sex disparities in the current era of pediatric heart transplantation in the United States

Sex-Based Differences in Rejection Among Pediatric Solid Organ Transplant Recipients

BACKGROUND

Immunosuppression is paramount to prevent acute rejection in solid organ transplant but also poses a risk for infection and malignancy. Identifying factors that influence rejection may allow for personalization of treatment and avoidance of an unnecessary degree of immunosuppression for the vulnerable pediatric population.

METHODS

We conducted a retrospective review analyzing public data provided by the Organ Procurement and Transplantation Network for pediatric patients listed for solid organ transplantation (kidney, liver, lung, and heart) from March 1998 to December 2022. Univariate and multivariate logistic regression was used to identify independent risk factors for treated acute rejection at 6 months and/or 1 year for liver, lung, kidney, and heart transplants.

RESULTS

The study population consisted of the following pediatric patients for each organ studied: liver (n = 8993), lung (n = 846), heart (n = 7118), and kidney (n = 14 600). At 1 year, 28.4% and 31.7% of males and females, respectively, were treated for rejection in liver transplant, 24.1% and 34.5%, respectively, for lung, 14.8% and 16.2%, respectively, for kidney, and 25.2% for both in heart transplant. In multivariate analysis, male recipient status was a statistically significant protective factor against rejection in liver transplant, OR = 0.85 (p < 0.001), lung transplant, OR = 0.61 (p = 0.004), and kidney transplant, OR = 0.91 (p = 0.040), but not heart transplant, OR = 0.96 (p = 0.460).

CONCLUSIONS

Our study demonstrates that pediatric males may have a lower risk of acute rejection in liver, lung, and kidney transplant yet not in heart transplant. These findings may have implications for the level of maintenance immunosuppression for pediatric male transplant recipients.

Sex-Based Disparities in Heart Transplantation in Teenagers

BACKGROUND

Heart transplantation in teenagers has not been well studied. Teenage recipients have unique considerations that influence outcomes-complexity of cardiac disease, wide range of donor sizing and age, mechanical support options, and medication nonadherence. We sought to analyze the outcomes of heart transplantation in teenagers, focusing on sex-based disparities.

METHODS

The United Network for Organ Sharing dataset was queried for patients 13 to 19 years of age who underwent heart transplantation from 2002 to 2021. Patients were divided into two groups based on sex. Baseline clinical characteristics were compared, along with an analysis of survival data. The primary outcome of interest was freedom from death or retransplantation.

RESULTS

Heart transplantation was performed in 2320 teenagers; 812 (35.0%) were female. Female recipients were smaller (54.0 vs. 62.0 kg, p < 0.0001) and less likely to have congenital heart disease (26.5 vs. 31.6%, p < 0.0001). Female patients also had fewer pre-transplant ventricular assist devices (24.7 vs. 32.2%, p = 0.0002). By multivariable analysis, female sex was independently associated with lower survival (HR 1.26 [CI 1.08-1.48], p = 0.003). Sex-mismatched female recipients had significantly lower survival than sex-matched male recipients (HR 1.29 [CI 1.06-1.58], p = 0.009). Donor: recipient age difference < 5 years and donor: recipient weight > 1.2 were independent predictors of higher survival (p < 0.05).

CONCLUSIONS

Female teenagers have lower survival following heart transplantation than their male counterparts. Male donor-female recipient transplants have the lowest survival among sex-matching groups. The use of organs from oversized or younger donors in teenagers may be considered to help improve post-transplant survival.

Mental Health Care for Children with Heart Disease and Their Families: Practical Approaches and Considerations for the Pediatric and Pediatric Cardiology Clinician

Mental health conditions are a common comorbidity among children living with heart disease. Children with congenital heart disease are more likely to have a mental health condition than their unaffected peers or peers with other chronic illnesses, and mental health risk persists across their lifetime. While poorer mental health in adults with congenital heart disease is associated with worse overall health outcomes, the association between mental health and cardiac outcomes for children with heart disease remains unknown. Despite this, it is suspected that mental health conditions go undiagnosed in children with heart disease and that many affected children and adolescents do not receive optimal mental health care. In this article, we review mental health in congenital heart disease across the lifespan, across domains of care, and across diagnoses. Further directions to support mental health care for children and adolescents with heart disease include practical screening and access to timely referral and mental health resources.

The Year in Cardiothoracic Transplant Anesthesia: Selected Highlights From 2022 Part II: Cardiac Transplantation

These highlights focus on research published in the year 2022 and is divided into preoperative, intraoperative, and postoperative sections. The preoperative section includes research on the assessment and optimization of candidates for heart transplantation; donor optimization and the use of extended donors; organ protection systems; donation after circulatory death allografts; recipient factors including cannabis use, sex, race, and comorbidities such as obesity, diabetes mellitus, and peripartum cardiomyopathy; the effects of the 2018 heart allocation policy change on waitlist and postoperative mortality; updates on heart transplantation in patients with coronavirus disease 2019; in pediatric patients; and those who require a bridge to transplant. The intraoperative section includes the use of a multidisciplinary team, a proposed transfusion algorithm, bench surgery on the allograft, and size matching. The postoperative section focuses on the research on the development and management of tricuspid regurgitation, echocardiography, arrhythmia management, and, finally, xenotransplantation.

Waitlist Outcomes for Pediatric Heart Transplantation in the Current Era: An Analysis of the Pediatric Heart Transplant Society Database

BACKGROUND

Waitlist mortality (WM) remains elevated in pediatric heart transplantation. Allocation policy is a potential tool to help improve WM. This study aims to identify patients at highest risk for WM to potentially inform future allocation policy changes.

METHODS

The Pediatric Heart Transplant Society database was queried for patients <18 years of age indicated for heart transplantation between January 1, 2010 to December 31, 2021. Waitlist mortality was defined as death while awaiting transplant or removal from the waitlist due to clinical deterioration. Because WM is low after the first year, analysis was limited to the first 12 months on the heart transplant list. Kaplan-Meier analysis and log-rank testing was conducted to compare unadjusted survival between groups. Cox proportional hazard models were created to determine risk factors for WM. Subgroup analysis was performed for status 1A patients based on body surface area (BSA) at time of listing, cardiac diagnosis, and presence of mechanical circulatory support.

RESULTS

In total 5974 children met study criteria of which 3928 were status 1A, 1012 were status 1B, 963 were listed status 2, and 65 were listed status 7. Because of the significant burden of WM experienced by 1A patients, further analysis was performed in only patients indicated as 1A. Within that group of patients, those with smaller size and lower eGFR had higher WM, whereas those patients without congenital heart disease or support from a ventricular assist device (VAD) at time of listing had decreased WM. In the smallest size cohort, cardiac diagnoses other than dilated cardiomyopathy were risk factors for WM. Previous cardiac surgery was a risk factor in the 0.3 to 0.7 m2 and >0.7 m2 BSA groups. VAD support was associated with lower WM other than in the single ventricle cohort, where VAD was associated with higher WM. Extracorporeal membrane oxygenation and mechanical ventilation were associated with increased risk of WM in all cohorts.

CONCLUSIONS

There is significant variability in WM among status-1A patients. Potential refinements to current allocation system should factor in the increased WM risk we identified in patients supported by extracorporeal membrane oxygenation or mechanical ventilation, single ventricle congenital heart disease on VAD support and small children with congenital heart disease, restrictive cardiomyopathy, or hypertrophic cardiomyopathy.

Public Reporting of Heart Transplant Center Performance: Promoting Clarity or Causing Confusion?

BACKGROUND

Transplant center report cards are publicly available and used by regulators, insurance payers, and importantly patients and families.

OBJECTIVES

In this study, the authors sought to evaluate the variability in reported public performance ratings of pediatric and adult heart transplant centers.

METHODS

Program-specific reports from the Scientific Registry of Transplant Recipients from 2017-2021 were used to evaluate stability, volatility, and reliability of 3 publicly reported ratings: waitlist survival (WS), getting to a faster transplant (FT), and post-transplantation graft failure (GF).

RESULTS

There were 112 adult and 55 pediatric centers. Over the study period, nearly all centers (98%) had at least 1 change in rating in at least 1 of the tiers. The average time to the first rating change of any magnitude was 12-18 months for all tiers and centers. For adult centers, the most volatile rating was WS (SD: 0.77), followed by GF (SD: 0.76) and then FT (SD: 0.57). For pediatric centers, the most volatile rating was WS (SD: 0.79), followed by both GF (SD: 0.66) and FT (SD: 0.68), which were equally volatile. All tiers except adult FT had an estimated Fleiss's kappa <0.20, indicating poor agreement/consistency across the study period. In addition, the intraclass correlation coefficient for all tiers was <0.50, indicating poor reliability.

CONCLUSIONS

The current 5-tier reporting of transplant center performance is highly volatile and has poor reliability and consistency. Given the unintended and significant negative consequences these reports can have, critical revision of these ratings is warranted.

Differences in excess mortality by recipient sex after heart transplant: An individual patient data meta-analysis

BACKGROUND

Identification of differences in mortality risk between female and male heart transplant recipients may prompt sex-specific management strategies. Because worldwide, males of all ages have higher absolute mortality rates than females, we aimed to compare the excess risk of mortality (risk above the general population) in female vs male heart transplant recipients.

METHODS

We used relative survival models conducted separately in SRTR and CTS cohorts from 1988-2019, and subsequently combined using 2-stage individual patient data meta-analysis, to compare the excess risk of mortality in female vs male first heart transplant recipients, accounting for the modifying effects of donor sex and recipient current age.

RESULTS

We analyzed 108,918 patients. When the donor was male, female recipients 0-12 years (Relative excess risk (RER) 1.13, 95% CI 1.00-1.26), 13-44 years (RER 1.17, 95% CI 1.10-1.25), and ≥45 years (RER 1.14, 95% CI 1.02-1.27) showed higher excess mortality risks than male recipients of the same age. When the donor was female, only female recipients 13-44 years showed higher excess risks of mortality than males (RER 1.09, 95% CI 1.00-1.20), though not significantly (p = 0.05).

CONCLUSIONS

In the setting of a male donor, female recipients of all ages had significantly higher excess mortality than males. When the donor was female, female recipients of reproductive age had higher excess risks of mortality than male recipients of the same age, though this was not statistically significant. Further investigation is required to determine the reasons underlying these differences.

Impact of center volume on outcomes after ventricular assist device implantation in pediatric patients: An analysis of the STS-Pedimacs database

BACKGROUND

To date, no pediatric studies have highlighted the impact of center's ventricular assist device (VAD) volumes on post implant outcomes.

METHODS

Children (age <19) enrolled in Pedimacs undergoing initial left ventricular assist device implantation from 2012 to 2020 were included. Center volume was analyzed as a continuous and categorical variable. For categorical analysis, center volumes were divided as: low volume (1-15 implants), medium volume (15-30 implants), and high volume (>30 implants) during our study period. Patient characteristics and outcomes were compared by center's VAD volumes.

RESULTS

Of 44 centers, 16 (36.4%) were low, 11 (25%) were medium, and 17 (38.6%) were high-volume centers. Children at high-volume centers were least likely intubated, sedated, or paralyzed, and most likely ambulating preimplant (p < 0.05 for all). Center's VAD volumes were not a significant risk factor for mortality post implant when treated as a continuous or a categorical variable (p > 0.05). Compared to low volume, children at high-volume centers had fewer early neurological events. Compared to medium volume, those at high-volume centers had fewer late bleeding events (p < 0.05 for all). There were no significant differences in survival after an adverse event by hospital volumes (p > 0.05).

CONCLUSIONS

Although hospital volume does not affect post-VAD implant mortality, pediatric centers with higher VAD volumes have fewer patients intubated, sedated, paralyzed pre implant, and have lower adverse events. Failure to rescue was not significantly different between low, medium, and high-volume VAD centers.

Review on clinician bias and its impact on racial and socioeconomic disparities in pediatric heart transplantation

This expert review seeks to highlight implicit bias in health care, transplant medicine, and pediatric heart transplantation to focus attention on the role these biases may play in the racial/ethnic and socioeconomic disparities noted in pediatric heart transplantation. This review breaks down the transplant decision making process to highlight points at which implicit bias may affect outcomes and discuss how the science of human decision making may help understand these complex processes.

Assessing Donor-Recipient Size Mismatch in Pediatric Heart Transplantation: Lessons Learned From Over 7,500 Transplants

BACKGROUND

To date, no studies have identified an optimal metric to match donor-recipient (D-R) pairs in pediatric heart transplantation (HT).

OBJECTIVES

This study sought to identify size mismatch metrics that predicted graft survival post-HT.

METHODS

D-R pairs undergoing HT in Pediatric Heart Transplant Society database from 1993 to 2021 were included. Effects of size mismatch by height, weight, body mass index, body surface area, predicted heart mass, and total cardiac volume (TCV) on 1- and 5-year graft survival and morbidity outcomes (rejection and cardiac allograft vasculopathy) were evaluated. Cox models with stepwise selection identified size metrics that independently predicted graft survival.

RESULTS

Of 7,715 D-R pairs, 36.0% were well matched (D-R ratio: -20% to +20%) by weight, 39.0% by predicted heart mass, 50.0% by body surface area, 57.0% by body mass index, 71.0% by height, and 93.0% by TCV. Of all size metrics, only D-R mismatch by height and TCV predicted graft survival at 1 and 5 years. Effects of D-R size mismatch on graft survival were nonlinear. At both 1 and 5 years post-HT, D-R undersizing and oversizing by height led to increased graft loss, with graft loss observed more frequently with undersizing. Moderately undersized donors by height (D-R ratio: <-30%) frequently experienced rejection post-HT (P < 0.001). Assessing D-R size matching by TCV, minimal donor undersizing was protective, while oversizing up to 25% was not associated with increased graft loss.

CONCLUSIONS

In pediatric HT, D-R appear most optimally matched using TCV. Only D-R size mismatch by TCV and height independently predicts graft survival. Standardizing size matching across centers may reduce donor discard.

30- and 60-Day Readmission Rates for Children With Heart Failure in the United States

BACKGROUND

Studies on readmission for pediatric heart failure (HF) patients is sparse.

OBJECTIVES

This study evaluated 30- and 60-day readmission rates in pediatric HF patients from 2010 to 2019.

METHODS

The authors used data from the Nationwide Readmission Database to evaluate trends in 30- and 60-day hospital readmissions among pediatric patients with HF and compare them with adults with HF. Readmissions were also stratified by sex, diagnosis, neighborhood income, and hospital volume.

RESULTS

There were 84,731 hospital admissions for HF. Compared with children without HF, those with HF were older, had Medicare/Medicaid insurance, and resided in micropolitan areas and low-income neighborhoods. The 30- (19.5% vs 3.1%) and 60-day (27.5% vs 4.3%) all-cause readmission rates were higher for children with HF compared with those without HF. Compared with children without HF, lengths of stay, deaths, and costs related to their readmission were higher for children readmitted with HF (P < 0.05 for all). There was no significant decline in pediatric HF-related 30- or 60- day readmissions during the study period overall, or for those with congenital heart disease (P > 0.05), unlike adult HF readmissions (P < 0.01). Infants were at highest risk, and readmission rates for teenagers are rising.

CONCLUSIONS

The 30- and 60-day readmission rates for pediatric patients with HF in the current era is high (∼20% and 30%, respectively). Unlike adult HF, pediatric HF readmission rates have not declined. Pediatric HF patients readmitted to the hospital have higher death rates and greater resource utilization than patients without HF. National measures to decrease readmissions for pediatric patients with HF is warranted.

Children from socioeconomically disadvantaged communities present in more advanced heart failure at the time of transplant listing

Transplant registries in the US do not collect information about community level risk factors. We utilized a community level socio-economic risk indicator, the distressed communities' index to understand its association with clinical presentation among children listed for heart transplant (HT). We found that currently, majority (40%) of children listed from distressed communities are Black. On multivariable analysis, compared to children from prosperous communities, those from distressed communities listed for HT were significantly more likely to be Status 1A (adjusted odds ratio [aOR] 1.39) and on a ventricular assist device (aOR 1.44). Compared to White children from prosperous communities, both Black and White children from distressed communities were more likely to be listed Status 1A (aOR 2.1 and 1.36 respectively) and have renal dysfunction (aOR 1.71 and 1.52 respectively). In conclusion, heart failure severity at listing appears more likely associated with community-level risk factors and less so with child's race/ethnicity.

Ventricular Assist Device Outcomes in Infants and Children With Stage 1 Single Ventricle Palliation

Data on ventricular assist device (VAD) outcomes in infants with stage 1 single ventricle (SV) palliation are limited. We examined the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) registry for outcomes of pre/poststage 1 SV patients undergoing VAD implantation between March 2018 and October 2020. Data are collected from 32 centers and major adverse events undergo central adjudication. During the study period, 30 stage 1 SV patients underwent VAD implant with median age of 0.9 months (range 0.1-25) and weight 3.7 kg (2.4-17). Preimplant illness severity was high: ventilator support (90%), ECMO (30%), prior cerebral vascular accident (CVA, 23%), and dialysis (13%). Devices used included paracorporeal pulsatile (50%), paracorporeal continuous-flow (37%), and multiple devices (13%). Median support duration was 56 days (range 3-246). A positive clinical outcome (transplanted or weaned) was attained in 63% (63% transplanted, 37% mortality, 0% weaned). VAD adverse events included: major infection (43%), neurologic dysfunction (any = 30%; CVA = 20%), major bleeding (17%), renal dysfunction (13%), and device malfunction (3%). In conclusion, stage 1 SV patients undergoing VAD support have high preimplant illness severity and complexity, as well as significant morbidity and mortality postimplant. A variety of devices and strategies are employed by centers to support this challenging population.

Patient and Device Selection in Pediatric MCS: A Review of Current Consensus and Unsettled Questions

The field of pediatric ventricular assist device (VAD) support has expanded significantly over the past 20 years, with one third of pediatric heart transplant recipients currently being bridged to transplant with a VAD. Despite increased pediatric VAD utilization, however, there remains little formalized guidance for patient or device selection. The population of children with advanced heart failure is quite heterogeneous, and the available data suggest that VAD outcomes vary significantly based upon patient size, anatomy, level of illness, and type of device implanted. In an effort to better understand current practice patterns and identify populations for whom there does not appear to be a consensus approach to achieving optimal VAD outcomes, the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has surveyed clinical decision-making among member sites and conducted a review of the available literature regarding patient population-specific VAD outcomes and center-specific practices related to patient and device selection. Rather than aiming to provide clinical guidelines, this document offers an overview of contemporary approaches to patient and device selection, highlighting specific populations for whom there is not a consensus approach to achieving reliably good VAD outcomes, as these populations may benefit most from future research and quality improvement efforts directed toward identifying best practice.

Waitlist Outcomes for Children With Congenital Heart Disease: Lessons Learned From Over 5000 Heart Transplant Listings in the United States

BACKGROUND

We evaluated the impact of pediatric heart-allocation policy changes over time and the approval of the Berlin ventricular assist device (VAD) on waitlist (WL) outcomes for children with congenital heart disease (CHD).

METHODS

The Scientific Registry of Transplant Recipients database was evaluated to include all children (age < 18) with CHD and cardiomyopathy (CMP) on the WL between 1999 and 2019, divided into 4 eras: Era 1 (1999-2008); Era 2 (2009-2011); Era 3 (2012-2016); and Era 4 (2016-2019). WL characteristics and survival outcomes were evaluated for patients with CHD over time and were compared to those with CMP listed currently (Era 4).

RESULTS

We included 5185 children with CHD on the WL during the study period; 1999 (39%) were listed in Era 1; 693 (13%) in Era 2; 1196 (23%) in Era 3; and 1297 (25%) in Era 4. Compared to the CHD WL in eras 1 and 2, those in Era 4 were less likely to be infants (48% vs 49% vs 43%), on mechanical ventilation (30% vs 26% vs 19%), on extracorporeal membrane oxygenation (15% vs 9.7% vs 6.2%), and were more likely to be on a VAD (2.4% vs 2.2% vs 6.0%) (P < .05 for all). WL survival improved in children with CHD from Era 1 to Era 4 (P < .001). However, in Era 4, children with CHD had lower WL survival than those with CMP (P < .001).

CONCLUSION

Children with CHD are increasingly being listed with less advanced heart failure, and they have had improved WL survival over time; however, WL outcomes remain inferior to those with CMP. Advances in pediatric medical and VAD therapy may improve future WL outcomes.

Social Inequalities in Non-ischemic Cardiomyopathies

Heart failure (HF) has various characteristics, such as etiology, clinical course, and clinical characteristics. Several studies reported the clinical findings of the characteristics of non-ischemic cardiomyopathy. There have been issues with genetic, biochemical, or pathophysiological problems. Some studies have been conducted on non-ischemic cardiomyopathy and social factors, for instance, racial disparities in peripartum cardiomyopathy (PPCM) or the social setting of hypertrophic cardiomyopathy. However, there have been insufficient materials to consider the relationship between social factors and clinical course in non-ischemic cardiomyopathies. There were various methodologies in therapeutic interventions, such as pharmacological, surgical, or rehabilitational, and educational issues. However, interventions that could be closely associated with social inequality have not been sufficiently elucidated. We will summarize the effects of social equality, which could have a large impact on the development and progression of HF in non-ischemic cardiomyopathies.