Primary Graft Dysfunction in Heart Transplant Recipients-Risk Factors and Longitudinal Outcomes

Sex and Gender-related Disparities in Clinical Characteristics and Outcomes in Heart Transplantation

PURPOSE OF REVIEW

Limited research has been conducted on sex disparities in heart transplant (HT). The aim of this review is to analyse the available evidence on the influence of sex and gender-related determinants in the entire HT process, as well as to identify areas for further investigation.

RECENT FINDINGS

Although women make up half of the population affected by heart failure and related mortality, they account for less than a third of HT recipients. Reasons for this inequality include differences in disease course, psychosocial factors, concerns about allosensitisation, and selection or referral bias in female patients. Women are more often listed for HT due to non-ischaemic cardiomyopathy and have a lower burden of cardiovascular risk factors. Although long-term prognosis appears to be similar for both sexes, there are significant disparities in post-HT morbidity and causes of mortality (noting a higher incidence of rejection in women and of malignancy and cardiac allograft vasculopathy in men). Additional research is required to gain a better understanding of the reasons behind gender disparities in eligibility and outcomes following HT. This would enable the fair allocation of resources and enhance patient care.

Impact of controlled hypothermic preservation on outcomes following heart transplantation

BACKGROUND

Severe primary graft dysfunction (PGD) is a major cause of early mortality after heart transplant, but the impact of donor organ preservation conditions on severity of PGD and survival has not been well characterized.

METHODS

Data from US adult heart-transplant recipients in the Global Utilization and Registry Database for Improved Heart Preservation-Heart Registry (NCT04141605) were analyzed to quantify PGD severity, mortality, and associated risk factors. The independent contributions of organ preservation method (traditional ice storage vs controlled hypothermic preservation) and ischemic time were analyzed using propensity matching and logistic regression.

RESULTS

Among 1,061 US adult heart transplants performed between October 2015 and December 2022, controlled hypothermic preservation was associated with a significant reduction in the incidence of severe PGD compared to ice (6.6% [37/559] vs 10.4% [47/452], p = 0.039). Following propensity matching, severe PGD was reduced by 50% (6.0% [17/281] vs 12.1% [34/281], respectively; p = 0.018). The Kaplan-Meier terminal probability of 1-year mortality was 4.2% for recipients without PGD, 7.2% for mild or moderate PGD, and 32.1%, for severe PGD (p < 0.001). The probability of severe PGD increased for both cohorts with longer ischemic time, but donor hearts stored on ice were more likely to develop severe PGD at all ischemic times compared to controlled hypothermic preservation.

CONCLUSIONS

Severe PGD is the deadliest complication of heart transplantation and is associated with a 7.8-fold increase in probability of 1-year mortality. Controlled hypothermic preservation significantly attenuates the risk of severe PGD and is a simple yet highly effective tool for mitigating post-transplant morbidity.

Recipient Outcomes With Extended Criteria Donors Using Advanced Heart Preservation: An Analysis of the GUARDIAN-Heart Registry

BACKGROUND

The prevalence of end-stage heart failure and patients who could benefit from heart transplantation requires an expansion of the donor pool, relying on the transplant community to continually re-evaluate and expand the use of extended criteria donor organs. Introduction of new technologies such as the Paragonix SherpaPak Cardiac Transport System aids in this shift. We seek to analyze the impact of the SherpaPak system on recipient outcomes who receive extended criteria organs in the GUARDIAN-Heart Registry.

METHODS

Between October 2015 and December 2022, 1,113 adults from 15 US centers receiving donor hearts utilizing either SherpaPak (n = 560) or conventional ice storage (ice, n = 453) were analyzed from the GUARDIAN-Heart Registry using summary statistics. A previously published set of criteria was used to identify extended criteria donors, which included 193 SherpaPak and 137 ice.

RESULTS

There were a few baseline differences among recipients in the 2 cohorts; most notably, IMPACT scores, distance traveled, and total ischemic time were significantly greater in SherpaPak, and significantly more donor hearts in the SherpaPak cohort had >4 hours total ischemia time. Posttransplant mechanical circulatory support utilization (SherpaPak 22.3% vs ice 35.0%, p = 0.012) and new extracorporeal membrane oxygenation/ventricular assist device (SherpaPak 7.8% vs ice 15.3%, p = 0.033) was significantly reduced, and the rate of severe primary graft dysfunction (SherpaPak 6.2% vs ice 13.9%, p = 0.022) was significantly reduced by over 50% in hearts preserved using SherpaPak. One-year survival between cohorts was similar (SherpaPak 92.9% vs ice 89.6%, p = 0.27).

CONCLUSIONS

This subgroup analysis demonstrates that SherpaPak can be safely used to utilize extended criteria donors with low severe PGD rates.

Donor Heart Recovery and Preservation Modalities in 2024

Historically, heart transplantation (HT) has relied on the use of traditional cold storage for donor heart preservation. This organ preservation modality has several limitations, including the risk for ischemic and cold-induced graft injuries that may contribute to primary graft dysfunction and poor post-HT outcomes. In recent years, several novel donor heart preservation modalities have entered clinical practice, including the SherpaPak Cardiac Transport System of controlled hypothermic preservation, and the Transmedics Organ Care System of ex vivo perfusion. Such technologies are altering the landscape of HT by expanding the geographic reach of procurement teams and enabling both donation after cardiac death and the use of expanded criteria donor hearts. This paper will review the emerging evidence on the association of these modalities with improved post-HT outcomes, and will also suggest best practices for selecting between donor heart preservation techniques.

A Paradigm Shift in Heart Preservation: Improved Post-transplant Outcomes in Recipients of Donor Hearts Preserved With the SherpaPak System

Traditional ice storage has been the historic standard for preserving donor's hearts. However, this approach provides variability in cooling, increasing risks of freezing injury. To date, no preservation technology has been reported to improve survival after transplantation. The Paragonix SherpaPak Cardiac Transport System (SCTS) is a controlled hypothermic technology clinically used since 2018. Real-world evidence on clinical benefits of SCTS compared to conventional ice cold storage (ICS) was evaluated. Between October 2015 and January 2022, 569 US adults receiving donor hearts preserved and transported either in SCTS (n = 255) or ICS (n = 314) were analyzed from the Global Utilization And Registry Database for Improved heArt preservatioN (GUARDIAN-Heart) registry. Propensity matching and a subgroup analysis of >240 minutes ischemic time were performed to evaluate comparative outcomes. Overall, the SCTS cohort had significantly lower rates of severe primary graft dysfunction (PGD) ( p = 0.03). When propensity matched, SCTS had improving 1-year survival ( p = 0.10), significantly lower rates of severe PGD ( p = 0.011), and lower overall post-transplant MCS utilization ( p = 0.098). For patients with ischemic times >4 hours, the SCTS cohort had reduced post-transplant MCS utilization ( p = 0.01), reduced incidence of severe PGD ( p = 0.005), and improved 30-day survival ( p = 0.02). A multivariate analysis of independent risk factors revealed that compared to SCTS, use of ice results in a 3.4-fold greater chance of severe PGD ( p = 0.014). Utilization of SCTS is associated with a trend toward increased post-transplant survival and significantly lower severe PGD and MCS utilization. These findings fundamentally challenge the decades-long status quo of transporting donor hearts using ice.

Health care resource utilization and clinical outcomes for adult heart transplant recipients with primary graft dysfunction

INTRODUCTION

The advent of new technologies to reduce primary graft dysfunction (PGD) and improve outcomes after heart transplantation are costly. Adoption of these technologies requires a better understanding of health care utilization, specifically the costs related to PGD.

METHODS

Records were examined from all adult patients who underwent orthotopic heart transplantation (OHT) between July 1, 2013 and July 30, 2019 at a single institution. Total costs were categorized into variable, fixed, direct, and indirect costs. Patient costs from time of transplantation to hospital discharge were transformed with the z-score transformation and modeled in a linear regression model, adjusted for potential confounders and in-hospital mortality. The quintile of patient costs was modeled using a proportional odds model, adjusted for confounders and in-hospital mortality.

RESULTS

359 patients were analyzed, including 142 with PGD and 217 without PGD. PGD was associated with a .42 increase in z-score of total patient costs (95% CI: .22-.62; p < .0001). Additionally, any grade of PGD was associated with a 2.95 increase in odds for a higher cost of transplant (95% CI: 1.94-4.46, p < .0001). These differences were substantially greater when PGD was categorized as severe. Similar results were obtained for fixed, variable, direct, and indirect costs.

CONCLUSIONS

PGD after OHT impacts morbidity, mortality, and health care utilization. We found that PGD after OHT results in a significant increase in total patient costs. This increase was substantially higher if the PGD was severe.

SUMMARY

Primary graft dysfunction after heart transplantation impacts morbidity, mortality, and health care utilization. PGD after OHT is costly and investments should be made to reduce the burden of PGD after OHT to improve patient outcomes.

Understanding and Investigating Sex-Based Differences in Heart Transplantation: A Call to Action

Women represent only about 25% of heart transplant recipients annually. Although the number of women living with advanced heart failure remains unknown, epidemiologic research suggests that more women should be receiving advanced heart failure therapies. Sex differences in risk factors, presentation, response to pharmacotherapy, and outcomes in heart failure have been well described. Yet, less is known about sex differences in heart transplant candidate selection, waitlist management, donor selection, perioperative considerations, and post-transplant management and outcomes. The purpose of this review was to summarize the existing published reports related to sex differences in heart transplantation, highlighting areas in which sex-based considerations are well described and supported by available evidence, and emphasizing topics that require further study.

Blood Type A1 Mismatch Does Not Affect Heart Transplant Outcomes at One Year

There are subtypes within blood type A, termed non-A1, that have reduced expression of A antigen on cell surfaces. This can result in the development of anti-A1 antibodies. There is limited information regarding the impact of this in heart transplant (HTx) recipients. We conducted a single-center cohort study of 142 Type A HTx recipients in which we compared outcomes of a match group (an A1/O heart into an A1 recipient or a non-A1/O heart into a non-A1 recipient) with a mismatch group (an A1 heart into a non-A1 recipient or a non-A1 heart into an A1 recipient). At one year post-transplant, there were no differences between the groups in survival, freedom from non-fatal major adverse cardiovascular events, freedom from any treated rejection, or freedom from cardiac allograft vasculopathy. There was an increased hospital length of stay in the mismatch group (13.5 vs. 17.1 days, p = 0.04). Our study showed that A1 mismatch was not associated with worse outcomes at one year post-HTx.