Predictors of Donor Heart Utilization for Transplantation in United States

Increasing Utilization of Extended Criteria Donor Hearts for Transplantation: The OCS Heart EXPAND Trial

BACKGROUND

Extended criteria donor (ECD) hearts available with donation after brain death (DBD) are underutilized for transplantation due to limitations of cold storage.

OBJECTIVES

This study evaluated use of an extracorporeal perfusion system on donor heart utilization and post-transplant outcomes in ECD DBD hearts.

METHODS

In this prospective, single-arm, multicenter study, adult heart transplant recipients received ECD hearts using an extracorporeal perfusion system if hearts met study criteria. The primary outcome was a composite of 30-day survival and absence of severe primary graft dysfunction (PGD). Secondary outcomes were donor heart utilization rate, 30-day survival, and incidence of severe PGD. The safety outcome was the mean number of heart graft-related serious adverse events within 30 days. Additional outcomes included survival through 2 years benchmarked to concurrent nonrandomized control subjects.

RESULTS

A total of 173 ECD DBD hearts were perfused; 150 (87%) were successfully transplanted; 23 (13%) did not meet study transplantation criteria. At 30 days, 92% of patients had survived and had no severe PGD. The 30-day survival was 97%, and the incidence of severe PGD was 6.7%. The mean number of heart graft-related serious adverse events within 30 days was 0.17 (95% CI: 0.11-0.23). Patient survival was 93%, 89%, and 86% at 6, 12, and 24 months, respectively, and was comparable with concurrent nonrandomized control subjects.

CONCLUSIONS

Use of an extracorporeal perfusion system resulted in successfully transplanting 87% of donor hearts with excellent patient survival to 2 years post-transplant and low rates of severe PGD. The ability to safely use ECD DBD hearts could substantially increase the number of heart transplants and expand access to patients in need. (International EXPAND Heart Pivotal Trial [EXPANDHeart]; NCT02323321; Heart EXPAND Continued Access Protocol; NCT03835754).

Specialized Thoracic Adapted Recovery Model for Thoracic Organ Recovery: a 15-Year Review

BACKGROUND

To review outcomes from a regionalized heart and lung transplant service over a 15-year period.

METHODS

Data on organ procurements made by the Specialized Thoracic Adapted Recovery (STAR) team. The STAR team staff recorded data from November 2, 2004 to June 30, 2020, were reviewed.

RESULTS

The STAR teams recovered thoracic organs from 1118 donors between November 2004 and June 2020. The teams recovered 978 hearts, 823 bilateral lungs, 89 right lungs and 92 left lungs, and 8 heart and lung sets. A total of 79% of hearts and 76.1% of lungs were transplanted, whereas 2.5% of hearts and 5.1% of lungs were declined; the remainder were used for research, valves, or abandoned. A total of 47 transplantation centers received at least 1 heart, and 37 centers received at least 1 lung during this period. The 24-hour graft survival among organs recovered by STAR teams was 100% for lungs and 99% for hearts.

CONCLUSIONS

A specialized regional thoracic organ procurement team may improve transplantation rates.

Association of donor hypertension and outcomes in orthotopic heart transplantation

The present study examined the impact of donor hypertension on recipient survival and offer acceptance practices in the United States. This was a retrospective study of all patients undergoing OHT from 1995 to 2019 using the United Network for Organ Sharing and Potential Transplant Recipient file databases. Hypertensive donors were stratified by Short (0-5 years) and Prolonged (> 5 years) hypertension. Multivariable logistic regression was used to analyze offer acceptance practices while Cox proportional-hazards models were used to compare mortality across groups. Of 38,338 heart transplants meeting study criteria, 5662 were procured from hypertensive donors (69% Short and 31% Prolonged). After adjustment, Prolonged donor hypertension was associated with increased mortality (hazard ratio, HR, 1.31, 95% confidence interval, CI, 1.04-1.64), while recipients of Short donors experienced no decrement in post-transplant survival. Both Short and Prolonged hypertension were independently associated with decreased odds of offer acceptance (odds ratio, OR .92 95%CI: .88-.96 and OR .93 95%CI: .88-.99, respectively). While prolonged untreated hypertension in OHT donors is associated with a slight decrement in recipient survival, donors with ≤5 years of hypertension yielded similar outcomes. Donor hypertension was associated with reduced organ offer acceptance, highlighting a potential source of organ underutilization.

Cardiac MicroRNA Expression Profile After Experimental Brain Death Is Associated With Myocardial Dysfunction and Can Be Modulated by Hypertonic Saline

BACKGROUND

Brain death (BD) is associated with systemic inflammatory compromise, which might affect the quality of the transplanted organs. This study investigated the expression profile of cardiac microRNAs (miRNAs) after BD, and their relationship with the observed decline in myocardial function and with the changes induced by hypertonic saline solution (HSS) treatment.

METHODS

Wistar rats were assigned to sham-operation (SHAM) or submitted to BD with and without the administration of HSS. Cardiac function was assessed for 6h with left ventricular (LV) pressure-volume analysis. We screened 641 rodent miRNAs to identify differentially expressed miRNAs (DEMs) in the heart and computational and functional analysis were performed to compare the DEMs and find their putative targets and their related enriched canonical pathways.

RESULTS

An enhanced expression in canonical pathways related to inflammation and myocardial apoptosis was observed in BD induced group, with two miRNAs, miR-30a-3p and miR-467f, correlating with the level of LV dysfunction observed after BD. Conversely, HSS treated after BD and SHAM groups showed similar enriched pathways related to the maintenance of heart homeostasis regulation, in agreement with the observation that both groups did not have significant changes in LV function.

CONCLUSIONS

These findings highlight the potential of miRNAs as biomarkers for assessing damage in BD donor hearts and to monitor the changes induced by therapeutic measures like HSS, opening a perspective to improve graft quality and to better understand the pathophysiology of BD. The possible relation of BD induced miRNA's on early and late cardiac allograft function must be investigated.Supplemental Visual Abstract; http://links.lww.com/TP/C210.

The adapted Heart Donor Score

The Heart Donor Score (HDS) predicts donor organ discard for medical reasons and survival after heart transplantation (HTX) in the Eurotransplant allocation system. Our aim was to adapt the HDS for application in the United Network for Organ Sharing (UNOS) registry. To adjust for differences between the Eurotransplant and UNOS registries, the "adapted HDS" was created (aHDS) by exclusion of the covariates "valve function," "left-ventricular hypertrophy," and exclusion of "drug abuse" from the variable "compromised history." Two datasets were analyzed to evaluate associations of the aHDS with donor organ discard (n = 70 948) and survival (n = 19 279). The aHDS was significantly associated with donor organ discard [odds ratio 2.72, 95% confidence interval (CI) 2.68-2.76, P < 0.001; c-statistic: 0.937). The score performed comparably in donors <60 and ≥60 years of age. The aHDS was a significant predictor of survival as evaluated by univariate Cox proportional hazards analysis (hazard ratio 1.04, 95% CI 1.01-1.07, P = 0.023), although the association lost significance in a multivariable model. The aHDS predicts donor organ discard. Negative effects of most aHDS components on survival are likely eliminated by highly accurate donor selection processes.

Impact of Deceased Donor Management on Donor Heart Use and Recipient Graft Survival

BACKGROUND

Current risk-adjusted models used to predict donor heart use and cardiac graft survival from organ donors after brain death (DBDs) do not include bedside critical care data. We sought to identify novel independent predictors of heart use and graft survival to better understand the relationship between donor management and transplantation outcomes.

STUDY DESIGN

We conducted a prospective observational study of DBDs managed from 2008 to 2013 by 10 organ procurement organizations. Demographic data, critical care parameters, and treatments were recorded at 3 standardized time points during donor management. The primary outcomes measures were donor heart use and cardiac graft survival.

RESULTS

From 3,433 DBDs, 1,134 hearts (33%) were transplanted and 969 cardiac grafts (85%) survived after 684 ± 392 days of follow-up. After multivariable analysis, independent positive predictors of heart use included standard criteria donor status (odds ratio [OR] 3.93), male sex (OR 1.68), ejection fraction > 50% (OR 1.64), and partial pressure of oxygen to fraction of inspired oxygen ratio > 300 (OR 1.31). Independent negative predictors of heart use included donor age (OR 0.94), BMI > 30 kg/m² (OR 0.78), serum creatinine (OR 0.83), and use of thyroid hormone (OR 0.78). As for graft survival, after controlling for known recipient risk factors, thyroid hormone dose was the only independent predictor (OR 1.04 per μg/h).

CONCLUSIONS

Modifiable critical care parameters and treatments predict donor heart use and cardiac graft survival. The discordant relationship between thyroid hormone and donor heart use (negative predictor) vs cardiac graft survival (positive predictor) warrants additional investigation.

Great variability in donor heart acceptance practices across the United States

Disparities in organ acceptance practices exacerbate donor heart nonuse and lead to increased waiting times and mortality for heart transplant candidates. We studied disparities in donor heart acceptance among US transplant centers and their relations to posttransplant outcomes. Candidate, potential transplant recipient match run, and deceased donor data were obtained from the United Network for Organ Sharing. We analyzed donor, candidate, and transplant center characteristics with respect to organ acceptance, offer acceptance, number of offers before acceptance (organ sequence number), and association with posttransplant mortality. A total of 693 420 donor heart offers made between April 2007 and December 2015 were included. We identified great variability in donor heart acceptance practices among US heart transplant centers. We identified donor and recipient characteristics that were strongly associated with heart organ and offer acceptance, and organ sequence number, and identified inconsistencies among centers with respect to how these characteristics influenced acceptance decisions. Finally, we identified characteristics that were highly predictive of donor heart nonuse and were not associated with increased recipient mortality, which may guide future efforts aimed at increasing use of available hearts for transplantation.

Review of the discard and/or refusal rate of offered donor hearts to pediatric waitlisted candidates

We aimed to review current literature on the discard rate of donor hearts offered to pediatric recipients and assess geographical differences. Consequences and ways to reduce the discard rate are discussed. A systemic review on published literature on pediatric transplantation published in English since 2010 was undertaken. Additionally, a survey was sent to international OPOs with the goal of incorporating responses from around the world providing a more global picture. Based on the literature review and survey, there is a remarkably wide range of discard and/or refusal for pediatric hearts offered for transplant, ranging between 18% and 57% with great geographic variation. The data suggest that that the overall refusal rate may have decreased over the last decade. Reasons for organ discard were difficult to identify from the available data. Although the refusal rate of pediatric donor hearts seems to be lower compared to that reported in adults, it is still as high as 57% with geographic variation.

Donor Heart Utilization in Korea

Background and Objectives

Donor heart utilization patterns in Korea are not well known. We aimed to analyze the current utilization rate of donor heart and to evaluate the reason for non-utilization in Korea.

Methods

Brain death donors were identified from the Korean Network for Organ Sharing registry from November 2009 to December 2019. Baseline characteristics and heart transplant related parameters were compared between transplanted and discarded donor hearts.

Results

Among 4,401 donors, 1,383 (31.4%) hearts were utilized. Hearts from younger, male donors without history of hypertension or diabetes mellitus were utilized more frequently. The most common blood type in the transplanted group was O, while blood type A was the most common blood type in the discarded group. The ejection fraction in the discarded group were significantly lower (57.0 ± 13.5% vs. 61.7 ± 7.0%, p<0.001). Reasons for non-utilization were as follows: medical condition (34.4%), old age (31.8%), refused by all candidates (22.5%), refused to donate (11.0%), and others (0.2%). The most common cause of brain death was cerebrovascular disease in both the transplanted and discarded groups, but the incidence was significantly higher in the discarded group (46.8% vs. 37.5%, p<0.001). In multivariate analysis, old age, small body surface area, rapid heart rate, blood type other than O, abnormal echocardiography findings were independent predictors for non-utilization.

Conclusions

Average donor heart utilization rate was 31.4% and it improved to 42.9% in 2019. However, substantial numbers of donor hearts are still discarded. A strategic approach to improve donor heart utilization is necessary.

Changing demographics of heart donors: The impact of donor drug intoxication on posttransplant survival

Recent reports have shown an increase in the number of organ donors from drug intoxication. The impact of donor drug use on survival after cardiac transplant remains unclear. The aim of our study was to illustrate changes in donor death mechanisms and assess the impact on posttransplant survival. We queried United Network of Organ Sharing thoracic transplant and deceased donor databases to identify patients undergoing heart transplantation between 2005 and 2015. We evaluated annual trends in donor death mechanisms. Recipients were propensity matched (drug-intoxicated-non-drug-intoxicated = 1:2) and posttransplant survival was compared using Kaplan-Meier curves. In total, 19 384 donor hearts were used for transplant during the period (donor age 31.6 ± 11.8 years, 72% male). Use of drug-intoxicated donors increased from 2% (2005) to 13% (2015) and decreased from blunt injury (40%-30%) and intracranial hemorrhage (29%-25%). After propensity matching, posttransplant survival of drug-intoxicated donor hearts was 90%, 82%, and 76% at 1, 3, and 5 years, which was similar to non-drug-intoxicated. Heart transplants using drug-intoxicated donors have significantly increased; however, they have not adversely affected posttransplant survival. Hearts from drug-intoxicated donors should be carefully evaluated and considered for transplant.