Effects of Older Donor Age and Cold Ischemic Time on Long-Term Outcomes of Heart Transplantation

Usage of older donors is associated with higher mortality after heart transplantation: A UNOS observational study

BACKGROUND

Utilization of heart from older donors is variable across centers with uncertain outcomes of recipients. We sought to utilize a national registry to examine the usage and outcomes of heart transplant (HT) recipients from older donors. We also explored the impact of current donor heart allocation scheme on the outcomes of hearts from older donors.

METHODS

This observational study utilized the United Network for Organ Sharing database between 2015 and 2023 with donors categorized into age <45 years or ≥45 years and evaluated organ disposition and geographical variation. Thirty-day, 1-, and 3-year mortality, and graft failure rates were compared among recipients as per donor age group. We also evaluated annual trends in HT for each group over the follow-up period.

RESULTS

A total of 24,966 adult donors were recovered: 3,742 (15.0%) were ≥45 years; 3,349 (15.6%) adults received heart from such donors with significant geographical variation, and a declining utilization in the transplantation rate in current donor allocation system. Donors with age ≥45 years had higher comorbidities and were allotted with a significantly shorter ischemic time to recipients who were significantly less likely to receive temporary mechanical circulatory support and more likely female. Unadjusted and adjusted, 30-day mortality were similar but 1- and 3-year mortality and graft failure rates were significantly higher in recipients of such donors. Spline analysis suggested a higher 1-year mortality risk at older donor age with risk increasing after age 40 years.

CONCLUSIONS

Older donor age was associated with worsened 1- and 3-year mortality and graft failure for heart transplant recipients.

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.

Short-term outcomes after heart transplantation using donor hearts preserved with ex vivo perfusion

The standard Conventional Cold Storage (CCS) during heart transplantation procurement is associated with time-dependent ischemic injury to the graft, which is a significant independent risk factor for post-transplant early morbidity and mortality - especially when cold ischemic time exceeds four hours. Since 2018, Rigshospitalet (Copenhagen, Denmark) has been utilising ex vivo perfusion (Organ Care System, OCS) in selected cases. The objective of this study was to compare the short-term clinical outcomes of patients transplanted with OCS compared to CCS. Methods: This retrospective single-centre study was based on consecutive patients undergoing a heart transplant between January 2018 and April 2021. Patients were selected for the OCS group when the cold ischemic time was expected to exceed four hours. The primary outcome measure was six-month event-free survival. Results: In total, 48 patients were included in the study; nine were transplanted with an OCS heart. The two groups had no significant differences in baseline characteristics. Six-month event-free survival was 77.8% [95% CI: 54.9-100%] in the OCS group and 79.5% [95% CI: 67.8-93.2%] in the CCS group (p = 0.91). While the OCS group had a median out-of-body time that was 183 min longer (p < 0.0001), the cold ischemic time was reduced by 51 min (p = 0.007). Conclusion: In a Scandinavian setting, our data confirms that utilising OCS in heart procurement allows for a longer out-of-body time and a reduced cold ischemic time without negatively affecting safety or early post-transplant outcomes.

Donor Heart Preservation: Current Knowledge and the New Era of Machine Perfusion

Heart transplantation remains the conventional treatment in end-stage heart failure, with static cold storage (SCS) being the standard technique used for donor preservation. Nevertheless, prolonged cold ischemic storage is associated with the increased risk of early graft dysfunction attributed to residual ischemia, reperfusion, and rewarming damage. In addition, the demand for the use of marginal grafts requires the development of new methods for organ preservation and repair. In this review, we focus on current knowledge and novel methods of donor preservation in heart transplantation. Hypothermic or normothermic machine perfusion may be a promising novel method of donor preservation based on the administration of cardioprotective agents. Machine perfusion seems to be comparable to cold cardioplegia regarding donor preservation and allows potential repair treatments to be employed and the assessment of graft function before implantation. It is also a promising platform for using marginal organs and increasing donor pool. New pharmacological cardiac repair treatments, as well as cardioprotective interventions have emerged and could allow for the optimization of this modality, making it more practical and cost-effective for the real world of transplantation. Recently, the use of triiodothyronine during normothermic perfusion has shown a favorable profile on cardiac function and microvascular dysfunction, likely by suppressing pro-apoptotic signaling and increasing the expression of cardioprotective molecules.

Introduction of machine perfusion of donor hearts in a single center in Germany

Introduction

Organ shortage, subsequent use of extended donor criteria organs and high-risk recipients needing redo-surgery are increasing the complexity of heart transplantation. Donor organ machine perfusion (MP) is an emerging technology allowing reduction of ischemia time as well as standardized evaluation of the organ. The aim of this study was to review the introduction of MP and analyze the results of heart transplantation after MP in our center.

Methods

In a retrospective single-center study, data from a prospectively collected database were analysed. From July 2018 to August 2021, fourteen hearts were retrieved and perfused using the Organ Care System (OCS), 12 hearts were transplanted. Criteria to use the OCS were based on donor/recipient characteristics. Primary objective was 30-day survival, secondary objectives were major cardiac adverse events, graft function, rejection episodes as well as overall survival in the follow-up and assessment of MP technical reliability.

Results

All patients survived the procedure and the postoperative 30-day interval. No MP related complications were noted. Graft ejection fraction beyond 14 days was ≥ 50% in all cases. Endomyocardial biopsy showed excellent results with no or mild rejection. Two donor hearts were rejected after OCS perfusion and evaluation.

Conclusion

Ex vivo normothermic MP during organ procurement is a safe and promising technique to expand the donor pool. Reduction of cold ischemic time while providing additional donor heart assessment and reconditioning options increased the number of acceptable donor hearts. Additional clinical trials are necessary to develop guidelines regarding the application of MP.

Impact of donor ventricular function on heart transplantation outcomes

BACKGROUND

Some heart transplant (HTx) centers have expanded their donor eligibility criteria in response to the organ shortage; one area of active interest involves utilizing hearts with ventricular dysfunction. Our study seeks to identify if a relationship exists between donor left ventricular ejection fraction (LVEF) and ischemic time or donor age on HTx outcomes.

METHODS

We performed a retrospective analysis on adult patients who had a HTx between 1996 and 2021 (n = 46,936). Donor LVEF (dLVEF) values were categorized into three groups: <50%, 50%-70%, and >70%. Ischemic time and donor age were stratified into four groups: ≤2.0, 2.1-3.0, 3.1-4.0, >4.0 h, and ≤30, 31-40, 41-50, >50 years, respectively. The outcome of interest was long-term survival.

RESULTS

Multivariable survival analysis found a slight increase in overall mortality risk for patients with donor ejection fractions <50% (HR = 1.16, p = .013). However, subsequent subgroup investigation discovered that this elevated hazard was only applicable when ischemic time was prolonged to >3.0 h (3.1-4.0 h: HR = 1.23, p = .024; > 4.0 h: HR = 1.52, p < .001). There was no significant difference in survival between dLVEF groups when ischemic time was limited to ≤3.0 h or when stratified by donor age.

CONCLUSION

HTx patients with a low donor ejection fraction have comparable survival to recipients with a normal dLVEF when ischemic time is limited to ≤3.0 h. Reduced dLVEF does not appear to be sensitive to advanced donor age. The clinical implications of our study may encourage the recruitment of more donor hearts for transplantation.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Early trends in cardiac allograft vasculopathy after implementation of the 2018 donor heart allocation policy in the United States

STUDY OBJECTIVE

To evaluate the impact of the new donor heart allocation system implemented in the United States in October 2018 on development of early cardiac allograft vasculopathy (CAV).

DESIGN

Retrospective cohort study.

PARTICIPANTS

Adult (≥ 18 years) heart transplant recipients registered in the United Network for Organ Sharing database between October 18, 2015 and October 17, 2018 (old system) and October 18, 2018 and May 31, 2020 (new system).

MAIN OUTCOME MEASURE

Incidence of angiographic CAV at 1 year (accelerated CAV) in the overall transplant population and among the highest acuity subgroup-Status 1A (old) and Status 1 or 2 (new). We included recipient and donor demographic, cardiovascular, and transplant factors in multivariable logistic regression models to identify predictors of accelerated CAV.

RESULTS

Of 10,375 transplant recipients, 6,660 (64%) and 3,715 (36%) were listed in the old and new allocation cohorts, respectively. The incidence of accelerated CAV was 521 (8%) in the old period compared with 272 (7%) in the new period (P = .36). Similar incidence rates were observed in the highest acuity subgroup-363 (8%) compared with 143 (7%), respectively (P = .13). In adjusted analyses of the high-acuity cohort, the new allocation system was not associated with a higher likelihood of accelerated CAV (odds ratio = 0.87, 95% confidence interval: 0.70-1.08, P = .20).

CONCLUSIONS

The new donor heart allocation system is not associated with development of accelerated angiographic CAV at 1 year, including among recipients requiring the most urgent transplants.

Heart Transplantation With Older Donors: Should There Be an Age Cutoff?

PURPOSE

Heart transplantation remains limited by donor availability. Currently, only some programs accept older donors, and their use remains contentious. We compared outcomes of heart transplant recipients who received donor hearts ≥55 years with those who received donor hearts <55 years.

METHODS

Records of first-time adult heart transplant recipients between 2010 and 2019 were reviewed. Endpoints included 30-day and 1-, 3-, and 5-year survival; freedom from cardiac allograft vasculopathy; freedom from nonfatal major adverse cardiac events; and freedom from any rejections. The effect of donor age ≥55 years was analyzed with Cox proportional hazards modeling, 1:2 propensity score matching, and Kaplan-Meier survival analysis.

RESULTS

Sixty-six patients received donor hearts ≥55 years and 766 received donor hearts <55 years. In the unmatched cohort, there was no significant difference in survival between the 2 groups at 30 days (93.9% vs 97.3%, P = .127), 1 year (87.9% vs 91.6%, P = .325), 3 years (86.4% vs 86.5%, P = .888), or 5 years (78.8% vs 83.8%, P = .497). The ≥55 years group had a significantly lower freedom from cardiac allograft vasculopathy and fatal major adverse cardiac events. In propensity-matched patients, recipients of donors ≥55 years had similar survival and freedom from cardiac allograft vasculopathy but significantly lower 1-year (76.7% vs 88.3%, P = .026), 3-year (68.3% vs 84.2%, P = .010), and 5-year (63.3% vs 83.3%, P = .002) freedom from nonfatal major adverse cardiac events when compared to recipients of younger donors.

CONCLUSIONS

Carefully selected older donors can be considered for a carefully selected group of recipients with acceptable outcomes.

Echocardiographic assessment of chamber size and ventricular function during the first year after heart transplantation

AIMS

Detecting changes in ventricular function after orthotopic heart transplantation (OHT) using transthoracic echocardiography (TTE) is important but interpretation of findings is complicated by lack of data on early graft adaptation. We sought to evaluate echocardiographic measures of ventricular size and function the first year following OHT including speckle tracking derived strain. We also aimed to compare echocardiographic findings to haemodynamic parameters obtained by right heart catheterization (RHC).

METHODS AND RESULTS

Fifty OHT patients were examined prospectively with TTE and RHC at 1, 6, and 12 months after OHT. Left ventricle (LV) was assessed with fractional shortening, ejection fraction and systolic tissue velocities. Right ventricular (RV) evaluation included tricuspid annular plane systolic excursion (TAPSE), systolic tissue velocity (S´) and fractional area change (FAC). LV global longitudinal and circumferential strain and RV global longitudinal strain (GLS) and RV lateral wall strain (RVfree) were analysed. No relevant changes occurred in LV echocardiographic parameters, whereas all measures of RV function improved significantly during follow-up. There was an increase in TAPSE (12.4 ± 3.3 mm to 14.4 ± 4.3 mm, p < .01), FAC (36% ± 8% to 41% ± 8%, p < .01), RV GLS (-15.8% ± 4% to -17.8% ± 3.6%, p < .01), and RVfree (-15.5% ± 3.7% to -18.6% ± 3.6%, p < .001). Between 1 and 12 months, pulmonary pressures decreased, whereas pulmonary vascular resistance did not.

CONCLUSION

Stable OHT recipients reached steady state regarding LV function 1 month after transplantation. In contrast, RV function displayed gradual improvement the first year following OHT, indicating delayed RV adaptation as compared to the LV. Improved RV function parameters were independent of invasively measured pulmonary pressures.

Cardiac Graft Assessment in the Era of Machine Perfusion: Current and Future Biomarkers

Heart transplantation remains the treatment of reference for patients experiencing end‐stage heart failure; unfortunately, graft availability through conventional donation after brain death is insufficient to meet the demand. Use of extended‐criteria donors or donation after circulatory death has emerged to increase organ availability; however, clinical protocols require optimization to limit or prevent damage in hearts possessing greater susceptibility to injury than conventional grafts. The emergence of cardiac ex situ machine perfusion not only facilitates the use of extended‐criteria donor and donation after circulatory death hearts through the avoidance of potentially damaging ischemia during graft storage and transport, it also opens the door to multiple opportunities for more sensitive monitoring of graft quality. With this review, we aim to bring together the current knowledge of biomarkers that hold particular promise for cardiac graft evaluation to improve precision and reliability in the identification of hearts for transplantation, thereby facilitating the safe increase in graft availability. Information about the utility of potential biomarkers was categorized into 5 themes: (1) functional, (2) metabolic, (3) hormone/prohormone, (4) cellular damage/death, and (5) inflammatory markers. Several promising biomarkers are identified, and recommendations for potential improvements to current clinical protocols are provided.

Ex situ heart perfusion: The past, the present, and the future

Despite the advancements in medical treatment, mechanical support, and stem cell therapy, heart transplantation remains the most effective treatment for selected patients with advanced heart failure. However, with an increase in heart failure prevalence worldwide, the gap between donor hearts and patients on the transplant waiting list keeps widening. Ex situ machine perfusion has played a key role in augmenting heart transplant activities in recent years by enabling the usage of donation after circulatory death hearts, allowing longer interval between procurement and implantation, and permitting the safe use of some extended-criteria donation after brainstem death hearts. This exciting field is at a hinge point, with 1 commercially available heart perfusion machine, which has been used in hundreds of heart transplantations, and a number of devices being tested in the pre-clinical and Phase 1 clinical trial stage. However, no consensus has been reached over the optimal preservation temperature, perfusate composition, and perfusion parameters. In addition, there is a lack of objective measurement for allograft quality and viability. This review aims to comprehensively summarize the lessons about ex situ heart perfusion as a platform to preserve, assess, and repair donor hearts, which we have learned from the pre-clinical studies and clinical applications, and explore its exciting potential of revolutionizing heart transplantation.

Local and regional variability in utilization and allocation of hepatitis C virus-infected hearts for transplantation

With the advent of direct-acting antiviral agents, there has been a rapid rise in hepatitis C virus-infected (HCV+) heart transplantation. We aimed to understand local and regional differences in utilization and allocation of HCV+ hearts. Using United Network for Organ Sharing (UNOS) de-identified data from January 1, 2016 to September 30, 2019 we compared trends in the utilization rates (hearts transplanted/donors recovered) of HCV-uninfected (HCV-) to those of HCV+ nonviremic (HCV-NV) and viremic (HCV-V) hearts nationally and by UNOS region. We also evaluated allocation rates (hearts successfully allocated/donors recovered) by organ procurement organization (OPO). We found that (1) in 2019, national utilization rates for HCV-NV and HCV-V hearts were the same as HCV- hearts (27.6% for HCV-NV, 30.9 for HCV-V, and 31.7% for HCV-, P = .277); (2) utilization rates of HCV-NV hearts were low in regions 3 and 4 and of HCV-V hearts in regions 3, 4, and 8 even in the contemporary period since 2018; and (3) there was marked variability in allocation of HCV+ hearts at the OPO level even within the same UNOS region. We conclude that despite national strides in the utilization of HCV+ hearts for transplantation, more aggressive allocation of HCV+ hearts at the OPO level may still significantly affect the organ shortage.

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 interactions between high-risk pediatric heart transplant recipients and marginal donors including utilization of risk score models

BACKGROUND

Donor organ acceptance practices vary among pediatric heart transplant professionals. We sought to understand what is known about the interactions between the "high-risk" recipient and the "marginal donor," and how donor risk scores can impact this discussion.

METHODS

A systematic review of published literature on pediatric HTx was undertaken with the assistance of a medical librarian. Two authors independently assessed search results, and papers were reviewed for inclusion.

RESULTS

We found that there are a large number of individual factors, and clusters of factors, that have been used to label individual recipients "high-risk" and individual donors "marginal." The terms "high-risk recipient" and "marginal donor" have been used broadly in the literature making it virtually impossible to make comparisons between publications. In general, the data support that patients who could be easily agreed to be "sicker recipients" are at more risk compared to those who are clearly "healthier," albeit still "sick enough" to need transplantation. Given this variability in the literature, we were unable to define how being a "high-risk" recipient interplays with accepting a "marginal donor." Existing risk scores are described, but none were felt to adequately predict outcomes from factors available at the time of offer acceptance.

CONCLUSIONS

We could not determine what makes a donor "marginal," a recipient "high-risk," or how these factors interplay within the specific recipient-donor pair to determine outcomes. Until there are better risk scores predicting outcomes at the time of organ acceptance, programs should continue to evaluate each organ and recipient individually.

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.

Use of Ventricular Assist Devices and Heart Transplantation for Advanced Heart Failure

There are only 2 treatments for the thousands of patients who progress to the most advanced form of heart failure despite the application of guideline-based medical therapy, use of ventricular assist devices and heart transplantation. There has been a great deal of progress in both of these therapies that have led to improved outcomes including significant improvement in survival and functional capacity. Heart transplantation offers the best short- and long-term survival for patients with end-stage heart failure, and the majority of these recipients achieve relatively limitless functional capacity for their age. However, the chronic shortage of available donors limits the number of recipients in the United States to an only 2500 patients/y or only a fraction of potential candidates. The significant improvement in outcomes now possible with durable ventricular assist devices has led to a significant increase in their use, which now exceeds the volume of heart transplants in the United States, with the greatest growth in use for those not considered to be candidates for heart transplantation, previously referred to as destination therapy. This article will review the substantial progress that has taken place for both of these life-saving treatment options, as well as the future directions.

Clinical outcome of donor heart with prolonged cold ischemic time: A single-center study

OBJECTIVES

Due to the shortage of donor pool, there has been a need for organs with prolonged cold ischemic time. This study aims to evaluate the short-term results of different cold ischemic times in orthotopic heart transplantation based on a single-center experience in China.

METHODS

We retrospectively analyzed outcomes of the heart transplant patients from 1 January 2015 to 31 December 2017. The recipient population was divided into four groups. Group 1: cold ischemic time greater than 8 hours; group 2: the cold ischemic time between 6 and 8 hours; group 3: the cold ischemic time between 4 and 6 hours; and group 4: cold ischemic time less than 4 hours. Efficacy indicators included after transplant survival, infection rate, rejection rate, and complications.

RESULTS

The four groups have similar donor and recipient baseline characteristics (P > .05). Cold ischemic time greater than 8 hours had more cardiopulmonary bypass (CPB) time (127.62 ± 50.23 minutes; P = .003), CPB-assist time (86.14 ± 36.74 minutes; P = .047), and higher intra-aortic balloon pump (IABP) usage rate postoperatively (47.36%; P = .010). Cold ischemic time greater than 8 hours witnessed a relatively higher mortality rate compared with the other three groups (P = .115, P =  .078, and P =  .114) during the 2-year follow-up. Survival rates of 1 and 2 years for the four groups were 78.95%, 87.13%, 87.32%, and 87.50% and 68.42%, 85.14%, 85.92%, and 83.93%, respectively.

CONCLUSION

Cold ischemic time less than 8 hours can be reasonably applied to expand the heart transplantation donor pool. Cold ischemic time greater than 8 hours might result in longer CPB time, CPB-assist time, and higher IABP usage postoperatively. It might also affect the in-hospital and 2-years survival rate.

Variability in donor selection among pediatric heart transplant providers: Results from an international survey

There is considerable variability in donor acceptance practices among adult heart transplant providers; however, pediatric data are lacking. The aim of this study was to assess donor acceptance practices among pediatric heart transplant professionals. The authors generated a survey to investigate clinicians' donor acceptance practices. This survey was distributed to all members of the ISHLT Pediatric Council in April 2018. A total of 130 providers responded from 17 different countries. There was a wide range of acceptable criteria for potential donors. These included optimal donor-to-recipient weight ratio (lower limit: 50%-150%, upper limit: 120%-350%), maximum donor age (25-75 years), and minimum acceptable left ventricular EF (30%-60%). Non-US centers demonstrated less restrictive donor selection criteria and were willing to accept older donors (50 vs 35 years, P < 0.001), greater size discrepancy (upper limit weight ratio 250% vs 200%, P = 0.009), and donors with a lower EF (45% vs 50%, P < 0.001). Recipient factors were most influential in the decision to accept marginal donors including recipients requiring ECMO support, ventilator support, and highly sensitized patients with a negative XM. However, programmatic factors impacted the decision to decline marginal donors including recent programmatic mortalities and concerns for programmatic restrictions from regulatory bodies. There is significant variation in donor acceptance practices among pediatric heart transplant professionals. Standardization of donor acceptance practices through the development of a consensus statement may help to improve donor utilization and reduce waitlist mortality.

Interaction Between Ischemic Time and Donor Age on Adult Heart Transplant Outcomes in the Modern Era

BACKGROUND

We examined the effect of cold ischemic interval on modern outcomes to determine whether advances in patient management have made an impact.

METHODS

Using the United Network of Organ Sharing database, we reviewed adult heart transplants between January 2000 and March 2016. We divided donor age into terciles: younger than 18 years, 18 to 33 years, and 34 years and older. Within each tercile, transplants were divided by cold ischemic interval of less than 4 hours, 4 to 6 hours, and more than 6 hours. Survival curves were compared between cold ischemic interval categories within each tercile. Covariate-adjusted and donor age-stratified Cox proportional hazards regression models were used to estimate overall mortality and graft failure hazards ratios.

RESULTS

Of 29,192 transplants, no significant differences between cold ischemic interval groups in survival or graft failure were apparent in the group aged younger than 18. For donors older than 18, significant differences were found for survival and graft failure with cold ischemic interval exceeding 4 hours in both univariate and multivariate analysis, and survival functions at different ischemic intervals continued to diverge beyond 1 year. The interaction effect between donor age and cold ischemic interval on overall mortality was not significant when analyzed as continuous variables, however younger donor age appeared to attenuate increase in overall mortality with longer cold ischemic intervals.

CONCLUSIONS

Despite advances in perioperative management during the past 30 years, for donors older than 18 years, cold ischemic interval exceeding 4 hours is associated with gradual but significantly diminished survival that persists well beyond the perioperative period. Comparison to historical data suggests that advances in management have somewhat attenuated the hazard associated with longer ischemic times.

Pathological Process of Prompt Connection between Host and Donor Tissue Vasculature Causing Rapid Perfusion of the Engineered Donor Tissue after Transplantation

The shortage of donors for transplantation therapy is a serious issue worldwide. Tissue engineering is considered a potential solution to this problem. Connection and perfusion in engineered tissues after transplantation is vital for the survival of the transplanted tissue, especially for tissues requiring blood perfusion to receive nutrients, such as the heart. A myocardial cell sheet containing an endothelial cell network structure was fabricated in vitro using cell sheet technology. Transplantation of the three-dimensional (3D) tissue by layering myocardial sheets could ameliorate ischemic heart disease in a rat model. The endothelial cell network in the 3D tissue was able to rapidly connect to host vasculature and begin perfusion within 24 h after transplantation. In this review, we compare and discuss the engineered tissue⁻host vasculature connection process between tissue engineered constructs with hydrogels and cell sheets by histological analysis. This review provides information that may be useful for further improvements of in vivo engineered tissue vascularization techniques.

Donor and recipient risk factor analysis of inferior postheart transplantation outcome in the era of durable mechanical assist devices

The study objective is to quantify the impact of donor and recipient variables on heart transplant survival in recipients with a significant proportion of implanted continuous-flow left ventricular assist devices (LVADs). This is a prospective cohort study of International Society for Heart and Lung Transplantation (ISHLT) Registry that includes all primary heart-alone transplants in adult recipients (January 2005 and June 2013, N = 15 532, 27% LVADs). Donor and recipient characteristics were assessed for association with death or graft failure within 90 days and between 90 days and 5 years after transplantation. On Cox proportional hazard model donor cause of death other than head trauma (hazard ratio [HR] 1.985, P < 0.0001), recipient congenital (HR 2.7555, P < 0.0001) and ischemic (HR 1.165, P = 0.0383) vs dilated etiology and female donor heart transplanted into male recipient (HR 1.207, P = 0.0354) were predictors of death or graft failure within 90 days. Between 90 days and 5 years, donor cigarette use (HR 1.232, P = 0.0001), recipient cigarette use (HR 1.193, P = 0.0003), diabetes (HR 1.159, P = 0.0050), arterial hypertension (HR 1.129, P = 0.0115), and ischemic vs dilative cardiomyopathy had an increased probability of death or graft failure.