Veno-Arterial Extracorporeal Membrane Oxygenation (VA-ECMO) Support in New Era of Heart Transplant

Heart failure is a serious and challenging medical condition characterized by the inability of the heart to pump blood effectively, leading to reduced blood flow to organs and tissues. Several underlying causes may be linked to this, including coronary artery disease, hypertension, or previous heart attacks. Therefore, it is a chronic condition that requires ongoing management and medical attention. HF affects >64 million individuals worldwide. Heart transplantation remains the gold standard of treatment for patients with end-stage cardiomyopathy. The recruitment of marginal donors may be considered an asset at the age of cardiac donor organ shortage. Primary graft dysfunction (PGD) is becoming increasingly common in the new era of heart transplantations. PGD is the most common cause of death within 30 days of cardiac transplantation. Mechanical Circulatory Support (MCS), particularly venoarterial extracorporeal membrane oxygenation (V-A ECMO), is the only effective treatment for severe PGD. VA-ECMO support ensures organ perfusion and provides the transplanted heart with adequate rest and recovery. In the new era of heart transplantation, early use allows for increased patient survival and careful management reduces complications.

Risk Index Predicts Pediatric Heart Allograft Non-Utilization

BACKGROUND

Children listed for heart transplantation face the highest waitlist mortality among all solid organ transplant patients (14%). Attempts at decreasing donor allograft non-utilization (41.5%) could potentially decrease waitlist mortality for pediatric heart transplant patients. Our aim was to quantify the non-utilization risk of pediatric donor heart allografts at the time of initial offering.

METHODS

Using the United Network of Organ Sharing (UNOS) database, we retrospectively analyzed 8823 deceased donors (≤18 years old) data through univariable and multivariable analysis and logistic regression models. These factors were divided into a training (n = 5882) and validation set (n = 2941). Donor clinical characteristics and laboratory values were used to predict non-utilization of donor hearts. The multivariable analysis used factors that were significant from the univariable analysis (p-value < .05), and the pediatric non-utilization risk index (pDRSI) included significant factors from the multivariable analysis, producing an overall risk score for non-utilization. With these data, we created a non-utilization risk index to predict likelihood of donor allograft non-utilization.

RESULTS

From the 24 potential factors that were identified from univariable analysis, 17 were significant predictors (p < .05) of pediatric heart non-utilization in the multivariable analysis. Low left ventricular ejection fraction (odds ratio (OR)-35.3), hepatitis C positive donor (OR-23.3), high left ventricular ejection fraction (OR-3.29), and hepatitis B positive donor (OR-3.27) were the most significant risk factors. The phDSRI has a C-statistic of 0.80 for the training set and 0.80 for the validation set.

CONCLUSION

Using over 8000 donors, the phDSRI uses 17 significant risk factors to predict risk of pediatric heart donor allograft non-utilization.

Disparities in donor heart acceptance between the USA and Europe: clinical implications

BACKGROUND AND AIMS

Given limited evidence and lack of consensus on donor acceptance for heart transplant (HT), selection practices vary widely across HT centres in the USA. Similar variation likely exists on a broader scale-across countries and HT systems-but remains largely unexplored. This study characterized differences in heart donor populations and selection practices between the USA and Eurotransplant-a consortium of eight European countries-and their implications for system-wide outcomes.

METHODS

Characteristics of adult reported heart donors and their utilization (the percentage of reported donors accepted for HT) were compared between Eurotransplant (n = 8714) and the USA (n = 60 882) from 2010 to 2020. Predictors of donor acceptance were identified using multivariable logistic regression. Additional analyses estimated the impact of achieving Eurotransplant-level utilization in the USA amongst donors of matched quality, using probability of acceptance as a marker of quality.

RESULTS

Eurotransplant reported donors were older with more cardiovascular risk factors but with higher utilization than in the USA (70% vs. 44%). Donor age, smoking history, and diabetes mellitus predicted non-acceptance in the USA and, by a lesser magnitude, in Eurotransplant; donor obesity and hypertension predicted non-acceptance in the USA only. Achieving Eurotransplant-level utilization amongst the top 30%-50% of donors (by quality) would produce an additional 506-930 US HTs annually.

CONCLUSIONS

Eurotransplant countries exhibit more liberal donor heart acceptance practices than the USA. Adopting similar acceptance practices could help alleviate the scarcity of donor hearts and reduce waitlist morbidity in the USA.

Heart transplantation in the era of corona virus disease 2019: Impact of the pandemic on donors, recipients and outcome

INTRODUCTION

Since March 2020, the COVID-19 pandemic has tremendously impacted health care all around the globe. We analyzed the impact of the pandemic on donors, recipients, and outcome of heart transplantation (HTx).

METHODS

Between 2010 and early 2022, a total of n = 235 patients underwent HTx in our department. Patients were assigned to the study groups regarding the date of the performed HTx. Group 1 (09/2010 to 02/2020): n = 160, Group 2 (03/2020 to 02/2022): n = 75.

RESULTS

Since the pandemic, the etiology of heart failure in the recipients has shifted from dilated (Group 1: 53.8%, Group 2: 32.0%) to ischemic cardiomyopathy (Group 1: 39.4%, Group 2: 50.7%, p < .01). The percentage of high urgency status of the recipients dropped from 50.0% to 36.0% (p = .05), and the use of left ventricular assist (LVAD) support from 56.9% to just 37.3% (p < .01). Meanwhile, the waiting time for the recipients also decreased by about 40% (p = .05). Since the pandemic, donors were 2- times more likely to have been previously resuscitated (Group 1: 21.3%, Group 2: 45.3% (p < .01), and drug abuse increased by more than 3-times (p < .01), indicating acceptance of more marginal donors. Surprisingly, the incidence of postoperative severe primary graft dysfunction requiring extracorporeal life support decreased from 33.1% to 19.4% (p = .04) since the pandemic.

CONCLUSION

The COVID-19 pandemic affected both donors and recipients of HTX but not the postoperative outcome. Donors nowadays are more likely to suffer from ischemic heart disease and are less likely to be on the high-urgency waitlist and on LVAD support. Simultaneously, an increasing number of marginal donors are accepted, leading to shorter waiting times.

Marginal versus Standard Donors in Heart Transplantation: Proper Selection Means Heart Transplant Benefit

BACKGROUND

In this study, we assessed the mid-term outcomes of patients who received a heart donation from a marginal donor (MD), and compared them with those who received an organ from a standard donor (SD).

METHODS

All patients who underwent HTx between January 2012 and December 2020 were enrolled at a single institution. The primary endpoints were early and long-term survival of MD recipients. Risk factors for primary graft failure (PGF) and mortality in MD recipients were also analyzed. The secondary endpoint was the comparison of survival of MD versus SD recipients.

RESULTS

In total, 238 patients underwent HTx, 64 (26.9%) of whom received an organ from an MD. Hospital mortality in the MD recipient cohort was 23%, with an estimated 1 and 5-year survival of 70% (59.2-82.7) and 68.1% (57.1-81), respectively. A multivariate analysis in MD recipients showed that decreased renal function and increased inotropic support of recipients were associated with higher mortality (p = 0.04 and p = 0.03). Cold ischemic time (p = 0.03) and increased donor inotropic support (p = 0.04) were independent risk factors for PGF. Overall survival was higher in SD than MD (85% vs. 68% at 5 years, log-rank = 0.008). However, risk-adjusted mortality (p = 0.2) and 5-year conditional survival (log-rank = 0.6) were comparable.

CONCLUSIONS

Selected MDs are a valuable resource for expanding the cardiac donor pool, showing promising results. The use of MDs after prolonged ischemic times, increased inotropic support of the MD or the recipient and decreased renal function are associated with worse outcomes.

Evaluation of donor heart for transplantation

Cardiac transplantation is considered the gold-standard treatment option for patients suffering from end-stage heart failure refractory to maximum medical therapy. A major determinant of graft function and recipient survival is a comprehensive evaluation of the donor allograft. Challenges arise when designing and implementing an evidence-based donor evaluation protocol due to the number of influential donor-specific characteristics and the complex interactions that occur between them. Here, we present our systematic approach to donor evaluation by examining the impact that relevant donor variables have on graft function and recipient outcomes.

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.

Allograft discard risk index for heart transplantation

BACKGROUND

The numberof patients awaiting heart transplantation (HTx) substantially exceeds the number of donor hearts transplanted each year, yet nearly 65% of eligible donor hearts are discarded rather than transplanted.

METHODS

Deceased organ donors listed within the UNOS Deceased Donor Database between 2010 and 2020 were reviewed. Those greater than 10 years old and consented for heart donation were included and randomly separated into training (n = 48 435) and validation (n = 24 217) cohorts. A discard risk index (DSRI) was created using the results of univariable and multivariable analyses. Discard data were assessed at DSRI value deciles, and stratum-specific likelihood ratio (SSLR) analysis and Kaplan-Meier survival function were used for mortality data.

RESULTS

Factors associated with higher DSRI values included donor age > 45, LVEF, HBV-core antibodies, hypertension, and diabetes. The DSRI C-statistic was .906 in the training cohort and .904 in the validation cohort. The DSRI did not reliably predict 30-day or 1-year mortality after transplantation (C-statistic .539 and .532, respectively).

CONCLUSIONS

The factors leading to heart allograft discard are not correlated to the same degree with post-transplant outcomes. This suggests that optimizing utilization of certain allografts with slightly higher risk of discard could increase the heart donor pool with limited impact on posttransplant mortality.

Incidence and impact of primary graft dysfunction in adult heart transplant recipients: A systematic review and meta-analysis

PURPOSE

Primary graft dysfunction (PGD) is a leading cause of early mortality after heart transplant (HTx). To identify PGD incidence and impact on mortality, and to elucidate risk factors for PGD, we systematically reviewed studies using the ISHLT 2014 Consensus Report definition and reporting the incidence of PGD in adult HTx recipients.

METHODS

We conducted a systematic search in January 2020 including studies reporting the incidence of PGD in adult HTx recipients. We used a random effects model to pool the incidence of PGD among HTx recipients and, for each PGD severity, the mortality rate among those who developed PGD. For prognostic factors evaluated in ≥2 studies, we used random effects meta-analyses to pool the adjusted odds ratios for development of PGD. The GRADE framework informed our certainty in the evidence.

RESULTS

Of 148 publications identified, 36 observational studies proved eligible. With moderate certainty, we observed pooled incidences of 3.5%, 6.6%, 7.7%, and 1.6% and 1-year mortality rates of 15%, 21%, 41%, and 35% for mild, moderate, severe and isolated right ventricular-PGD, respectively. Donor factors (female sex, and undersized), recipient factors (creatinine, and pre-HTx use of amiodarone, and temporary or durable mechanical support), and prolonged ischemic time proved associated with PGD post-HTx.

CONCLUSION

Our review suggests that the incidence of PGD may be low but its risk of mortality high, increasing with PGD severity. Prognostic factors, including undersized donor, recipient use of amiodarone pre-HTx and recipient creatinine may guide future studies in exploring donor and/or recipient selection and risk mitigation strategies.

Impact of donor-recipient age on cardiac transplant survival. Subanalysis of the Spanish Heart Transplant Registry

INTRODUCTION AND OBJECTIVES

The age of heart transplant recipients and donors is progressively increasing. It is likely that not all donor-recipient age combinations have the same impact on mortality. The objective of this work was to compare survival in transplant recipients according to donor-recipient age combinations.

METHODS

We performed a retrospective analysis of transplants performed between 1 January 1993 and 31 December 2017 in the Spanish Heart Transplant Registry. Pediatric transplants, retransplants and combined transplants were excluded (6505 transplants included). Four groups were considered: a) donor <50 years for recipient <65 years; b) donor <50 years for recipient ≥ 65 years; c) donor ≥ 50 years for recipient ≥ 65 years, and d) donor ≥ 50 years for recipient <65 years.

RESULTS

The most frequent group was young donor for young recipient (73%). There were differences in the median survival between the groups (P <.001): a) younger-younger: 12.1 years, 95%CI, 11.5-12.6; b) younger-older: 9.1 years, 95%CI, 8.0-10.5; c) older-older: 7.5 years, 95%CI, 2.8-11.0; d) older-younger: 10.5 years, 95%CI, 9.6-12.1. On multivariate analysis, independent predictors of mortality were the age of the donor and the recipient (0.008 and 0.001, respectively). The worst combinations were older-older vs younger-younger (HR, 1.57; 95%CI, 1.22-2.01; P <.001) and younger-older vs younger-younger (HR, 1.33; 95%CI, 1.12-1.58; P=.001).

CONCLUSIONS

Age (of the donor and recipient) is a relevant prognostic factor in heart transplant. The donor-recipient age combination has prognostic implications that should be identified when accepting an organ for transplant.

Review of the impact of donor characteristics on pediatric heart transplant outcomes

Heart transplantation (HTx) is a treatment option for end-stage heart failure in children. HTx is limited by the availability and acceptability of donor hearts. Refusal of donor hearts has been reported to be common with reasons for refusal including preexisting donor characteristics. This review will focus on the impact of donor characteristics and comorbidities on outcomes following pediatric HTx. A literature review was performed to identify articles on donor characteristics and comorbidities and pediatric HTx outcomes. There are many donor characteristics to consider when accepting a donor heart. Weight-based matching is the most common form of matching in pediatric HTx with a donor-recipient weight ratio between 0.7 and 3 having limited impact on outcomes. From an age perspective, donors <50 years can be carefully considered, but the impact of ischemic time needs to be understood. To increase the donor pool, with minimal impact on outcomes, ABO-incompatible donors should be considered in patients that are eligible. Other factors to be considered when accepting an organ is donor comorbidities. Little is known about donor comorbidities in pediatric HTx, with most of the data available focusing on infections. Being aware of the potential infections in the donor, understanding the testing available and risks of transmission, and treatment options for the recipient is essential. There are a number of donor characteristics that potentially impact outcomes following pediatric HTx, but these need to be taken into consideration along with their interactions with recipient factors when interpreting the outcomes following HTx.

ISHLT consensus statement on donor organ acceptability and management in pediatric heart transplantation

The number of potential pediatric heart transplant recipients continues to exceed the number of donors, and consequently the waitlist mortality remains significant. Despite this, around 40% of all donated organs are not used and are discarded. This document (62 authors from 53 institutions in 17 countries) evaluates factors responsible for discarding donor hearts and makes recommendations regarding donor heart acceptance. The aim of this statement is to ensure that no usable donor heart is discarded, waitlist mortality is reduced, and post-transplant survival is not adversely impacted.

Noteworthy Literature Published in 2017 for Thoracic Transplantation Anesthesiologists

Thoracic organ transplantation constitutes a significant proportion of all transplant procedures. Thoracic solid organ transplantation continues to be a burgeoning field of research. This article presents a review of remarkable literature published in 2017 regarding perioperative issues pertinent to the thoracic transplant anesthesiologists.