Geographic disparities in heart transplantation persist under the new allocation policy

Domino partial heart transplantation

Heart valve replacement in pediatric cardiothoracic surgery poses problems because conventional heart valve implants do not have the ability to grow. This mandates serial reoperations for implant exchanges until an adult-size implant can fit. Partial heart transplantation eliminates these reoperations because the transplanted valves grow. However, partial heart transplantation competes with heart transplantation for a limited supply of donor hearts. This is a critical barrier to the progress of the field. Domino partial heart transplantation is a new surgical technique that overcomes this barrier by capitalizing cardiectomy hearts from heart transplant recipients for partial heart transplantation. This surgical technique has the potential to transform pediatric heart valve replacement by greatly expanding the cardiac donor pool, increasing the time available for matching donors with recipients and simplifying the logistics of donation. As a result, the number of domino partial heart transplants is expected to exceed the number of partial heart transplants from deceased donors.

Evaluating the mechanism of action behind controlled hypothermic preservation of donor hearts: A randomized pilot study

BACKGROUND

Controlled hypothermic preservation of donor hearts is associated with decreased post-transplant primary graft dysfunction compared to conventional cold storage. However, mechanisms underlying this benefit in human subjects are unclear.

METHODS

We randomized 20 heart transplant recipients at a single institution to receive donor hearts preserved with either controlled hypothermic preservation or standard cold storage. Right ventricular biopsies were obtained at donor heart recovery, immediately before implantation, and 7 days after transplantation. Protein expression profiles at each time point were evaluated using mass spectrometry, Protein Interaction Network Extractor analysis, and Ingenuity Pathway Analysis.

RESULTS

Immediately before implantation, controlled hypothermic preservation was associated with increased protein expression related to fatty acid metabolism, mitochondrial intermembrane space, and contractile fiber machinery. Pathway analysis indicated increased cell viability, autophagy, and upregulation of AMP-activated protein kinase pathway with controlled hypothermic preservation. By post-transplant day 7, the protein expression profiles of the 2 groups were similar. However, controlled hypothermic preservation was associated with increased expression in the peroxisome proliferator-activated receptor signaling pathway and fatty acid oxidation.

CONCLUSIONS

Controlled hypothermic preservation of donor hearts shows beneficial time-dependent variability in protein expression that may confer improved organ quality at the time of transplantation.

Improving the Prioritization of Heart Transplantation Candidates for Optimal Clinical Outcomes: A Narrative Review

PURPOSE OF REVIEW

This narrative review evaluates the limitations of current heart transplantation allocation models, which prioritize medical urgency and waitlist time but fail to adequately predict long-term post-transplant outcomes. It aims to identify advanced metrics that can strengthen the prioritization framework while addressing persistent racial, geographic, and socioeconomic inequities in access to transplantation.

RECENT FINDINGS

Recent research indicates that incorporating frailty, nutritional status, immunological compatibility, and pulmonary hemodynamics into allocation frameworks can enhance the prediction of transplant outcomes. The growing use of mechanical circulatory support (MCS) as a bridge to transplantation provides stabilization for critically ill patients; however, disparities in access persist. Studies continue to emphasize the barriers faced by minority and pediatric populations, highlighting the need for expanded donor networks and improved matching criteria. This review highlights the necessity of shifting transplantation prioritization toward multidimensional candidate evaluations that consider both clinical complexity and long-term outcomes. Policy reforms aimed at addressing healthcare disparities and optimizing donor utilization are crucial for improving patient outcomes. Future research should focus on assessing the effectiveness of advanced allocation models, such as continuous distribution frameworks, to promote equitable and sustainable transplantation systems.

Bridge to Transplantation: Policies Impact Practices

Since the development of the first heart allocation system in 1988 to the most recent heart allocation system in 2018, the road to heart transplantation has continued to evolve. Policies were shaped with advances in temporary and durable left ventricular assist devices as well as prioritization of patients based on degree of illness. Herein, we review the changes in the heart allocation system over the past several decades and the impact of practice patterns across the United States.

Characterizing Adaptive Changes and Patient Survival After 2018 Donor Allocation Restructuring: A UNOS Database Analysis

PURPOSE

We sought to characterize adaptive changes to the revised United Network for Organ Sharing donor heart allocation policy and estimate long-term survival trends for heart transplant (HTx) recipients.

METHODS

Patients listed for HTx between October 17, 2013 and September 30, 2021 were identified from the United Network for Organ Sharing database, and stratified into pre- and postpolicy revision groups. Subanalyses were performed to examine trends in device utilization for extracorporeal membranous oxygenation (ECMO), durable left ventricular assist device (LVAD), intra-aortic balloon pump (IABP), microaxial support (Impella), and no mechanical circulatory support (non-MCS). Survival data post-HTx were fitted to parametric distributions and extrapolated to 5 years.

RESULTS

We identified 27,523 HTx waitlist candidates during the study period, most of whom (n = 16,376) were waitlisted in the prepolicy change period. Overall, 19,554 patients underwent HTx during the study period (pre: 12,037 and post: 7517). Listings increased after the policy change for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients. Listings for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients decreased. HTx increased for ECMO ( P < 0.01), Impella ( P < 0.01), and IABP ( P < 0.01) patients after the policy change and decreased for LVAD ( P < 0.01) and non-MCS ( P < 0.01) patients. Waitlist survival increased for the overall ( P < 0.01), ECMO ( P < 0.01), IABP ( P < 0.01), and non-MCS ( P < 0.01) groups. Waitlist survival did not differ for the LVAD ( P = 0.8) and Impella ( P = 0.1) groups. Post-transplant survival decreased for the overall ( P < 0.01), LVAD ( P < 0.01), and non-MCS ( P < 0.01) populations.

CONCLUSIONS

Allocation policy revisions have contributed to greater utilization of ECMO, Impella, and IABP, decreased utilization of LVADs and non-MCS, increased waitlist survival, and decreased post-HTx survival.

Outcomes related to hospital characteristics of heart transplant centers: A National Readmission Database analysis

Background

This study showcases an analysis performed using the National Readmission Database (NRD) from 2016 to 2019 to analyze the impact of ownership, location, size, and teaching status of transplant centers on cardiac transplant outcomes.

Methods

Demographic variables and hospital characteristics were identified using NRD data and International Classification of Diseases,10th revision codes. Comorbidities were assessed using the Elixhauser comorbidity index. Multivariable linear and logistic regression analyses were used to assess in-hospital mortality, 30-day and 180-day readmission rates, length of stay, days from admission to procedure, transfer to a rehab center, graft rejection, graft failure, and index admission total cost.

Results

Most cardiac transplants occurred in privately owned, large metropolitan areas, large bed size, and teaching centers. No significant difference was seen in in-hospital mortality, graft rejection, or graft failure by hospital ownership, location, size, or teaching status. Patients in private hospitals were more likely to be readmitted at 180 days and less likely to be transferred to rehab center compared to government-owned hospitals. Patients in private, small bed size, and teaching centers were more likely to have shorter length of stay. Additionally, days of admission to procedure were shorter in small bed size and teaching centers. Furthermore, the cost of index-hospital stay was higher in privately owned, large metropolitan areas, large bed size, and teaching centers.

Conclusions

While in-hospital mortality was not significantly different, various other outcomes related to cost and efficiency seem to be impacted by hospital characteristics.

Heart Transplantation

Heart transplantation (HTx) remains the last therapeutic resort for patients with advanced heart failure. The present work is a clinically focused review discussing current issues in heart transplantation. Several factors have been associated with the outcome of HTx, such as ABO and HLA compatibility, graft size, ischemic time, age, infections, and the cause of death, as well as imaging and laboratory tests. In 2018, UNOS changed the organ allocation policy for HTx. The aim of this change was to prioritize patients with a more severe clinical condition resulting in a reduction in mortality of people on the waiting list. Advanced heart failure and resistant angina are among the main indications of HTx, whereas active infection, peripheral vascular disease, malignancies, and increased body mass index (BMI) are important contraindications. The main complications of HTx include graft rejection, graft angiopathy, primary graft failure, infection, neoplasms, and retransplantation. Recent advances in the field of HTx include the first two porcine-to-human xenotransplantations, the inclusion of hepatitis C donors, donation after circulatory death, novel monitoring for acute cellular rejection and antibody-mediated rejection, and advances in donor heart preservation and transportation. Lastly, novel immunosuppression therapies such as daratumumab, belatacept, IL 6 directed therapy, and IgG endopeptidase have shown promising results.

Increased disparities in waitlist and post-heart transplantation outcomes according to socioeconomic status with the new heart transplant allocation system

BACKGROUND

The study objective was to assess disparities in outcomes in the waitlist and post-heart transplantation (HT) according to socioeconomic status (SES) in the old and new U.S. HT allocation systems.

METHODS

Adult HT candidates in the United Network for Organ Sharing database from 2014 through 2021 were included. Old or new system classification was according to listing before or after October 18, 2018. SES was stratified by patient ZIP code and median household income via U.S. Census Bureau and classified into terciles. Competing waitlist outcomes and post-transplantation survival were compared between systems.

RESULTS

In total, 26,450 patients were included. Waitlisted candidates with low SES were more frequently younger, female, African American, and with higher body mass index. Reduced cumulative incidence (CI) of HT in the old system occurred in low SES (53.5%) compared to middle (55.7%, p = 0.046), and high (57.9%, p < 0.001). In the new system, the CI of HT was 65.3% in the low SES vs middle (67.6%, p = 0.002) and high (70.2%, p < 0.001), and SES remained significant in the adjusted analysis. In the old system, CI of death/delisting was similar across SES. In the new system, low SES had increased CI of death/delisting (7.4%) vs middle (6%, p = 0.012) and high (5.4%, p = 0.002). The old system showed similar 1-year survival across SES. In the new system, recipients with low SES had decreased 1-year survival (p = 0.041).

CONCLUSIONS

SES affects waitlist and post-transplant outcomes. In the new system, all SES had increased access to HT; however, low SES had increased death/delisting due to worsening clinical status and decreased post-transplant survival.

Mitigating Health Disparities in Transplantation Requires Equity, Not Equality

Despite decades of research and evidence-based mitigation strategies, disparities in access to transplantation persist for all organ types and in all stages of the transplant process. Although some strategies have shown promise for alleviating disparities, others have fallen short of the equity goal by providing the same tools and resources to all rather than tailoring the tools and resources to one's circumstances. Innovative solutions that engage all stakeholders are needed to achieve equity regardless of race, sex, age, socioeconomic status, or geography. Mitigation of disparities is paramount to ensure fair and equitable access for those with end-stage disease and to preserve the trust of the public, upon whom we rely for their willingness to donate organs. In this overview, we present a summary of recent literature demonstrating persistent disparities by stage in the transplant process, along with policies and interventions that have been implemented to combat these disparities and hypotheses for why some strategies have been more effective than others. We conclude with future directions that have been proposed by experts in the field and how these suggested strategies may help us finally arrive at equity in transplantation.

Heart Transplant Waitlist Outcomes and Wait Time by Center Volume in the Pre-2018 Allocation Change Era

Although the transplant outcomes of centers are heavily monitored and compared, with a particular link between posttransplant outcomes and center volume demonstrated, little data exist comparing waitlist outcomes. Here, we explored waitlist outcomes by transplant center volume. We performed a retrospective analysis of adults listed for primary heart transplantation (HTx) from 2008 to 2018 using the United Network for Organ Sharing database. Transplant centers were split into low (<10 HTx/year), medium (10-30 HTx/year), and high (>30 HTx/year) volume, and waitlist outcomes were compared. Of the 35,190 patients included in our study, 23,726 (67.4%) underwent HTx, 4,915 (14.0%) died or deteriorated before receiving HTx, 1,356 (3.9%) were delisted due to recovery, and 1,336 (3.8%) underwent left ventricular assist device (LVAD) implantation. High-volume centers had higher rates of survival to transplant (71.3% vs. 60.6% for low-volume centers and 64.9% for medium-volume centers), and low rates of death or deterioration (12.6% vs. 14.6% for low-volume centers and 15.1% for medium-volume centers). Listing at a low-volume center was independently associated with death or delisting before HTx (HR 1.18, p = 0.007), whereas listing at a high-volume center (HR 0.86; p < 0.001) and prelisting LVAD (HR 0.67, p < 0.001) were protective. Death or delisting before HTx was lowest for patients listed in higher volume centers.

Disparities in heart transplantation

PURPOSE OF REVIEW

Heart transplantation remains the gold standard therapy for end stage heart failure, but barriers remain, preventing equitable access to and affecting outcomes following transplantation. The objective of this review is to summarize current and historical literature on the disparities that persist, and to highlight the gaps in evidence for further investigation.

RECENT FINDINGS

Although progress has been made to increase the rates of advanced heart failure therapies to racial/ethnic minority populations and those with lower socioeconomic status, differential access and outcomes remain. The disparities that persist are categorized by patient demographics, social influences, geopolitical factors, and provider bias.

SUMMARY

Disparities in heart transplantation exist, which span a wide spectrum. Healthcare professionals need to be cognizant of these disparities that patients face in terms of access to and outcomes for heart transplantation. Further research and system changes are needed to make heart transplantation a fairer option for patients of varying backgrounds with end stage heart failure.