Sensitization in Heart Transplantation: Emerging Knowledge: A Scientific Statement From the American Heart Association

Summary of a Consensus Conference on the Management of Highly Sensitized Multiorgan Transplant Candidates

The number of highly sensitized patients in need of a multiorgan transplant is increasing. Criteria informing their transplant candidacy, approaches to management on the waitlist, and protocols related to alloantibody monitoring vary widely. We convened a consensus conference to discuss these different practices in the United States and the United Kingdom and to review the contemporary outcomes of these challenging cases. A detailed analysis of the data regarding the liver allografts' immunoprotective effect on simultaneously transplanted other organs was also completed, and the prospect of the use of liver allografts primarily to facilitate transplantation of highly sensitized patients in need of other organs was discussed. The ethical and allocation-related issues about such prospect were debated with a goal to standardize the approach and provide an evidence-based pathway for pre-, peri-, and post-transplantation management for the highly sensitized multiorgan transplantation candidate.

Donor Selection for Heart Transplantation in 2025

The number of candidates on the waiting list for heart transplantation (HT) continues to far outweigh the number of available organs, and the donor heart nonuse rate in the United States remains significantly higher than that of other regions such as Europe. Although predicting outcomes in HT remains challenging, our overall understanding of the factors that play a role in post-HT outcomes continues to grow. We observe that many donor risk factors that are deemed "high-risk" do not necessarily always adversely affect post-HT outcomes, but are in fact nuanced and interact with other donor and recipient risk factors. The field of HT continues to evolve, with ongoing development of technologies for organ preservation during transport, expansion of the practice of donation after circulatory death, and proposed changes to organ allocation policy. As such, the field must continue to refine its processes for donor selection and risk prediction in HT.

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.

The Society of Thoracic Surgeons Intermacs 2024 Annual Report: Focus on Outcomes in Younger Patients

The 15th Annual Report from The Society of Thoracic Surgeons Interagency Registry for Mechanically Assisted Circulatory Support includes 29,634 continuous-flow left ventricular assist devices from the 10-year period between 2014 and 2024. The outcomes reported here demonstrate continued improved survival in the current era of fully magnetically levitated devices, with a significantly higher 1-year (85.7% vs 78.4%) and 5-year (59.7% vs 43.7%) survival than those receiving non-magnetically levitated devices. Magnetically levitated device recipients are experiencing a lower incidence of adverse events, including freedom from gastrointestinal bleeding (72.6%), device malfunction (82.9%), and stroke (86.7%) at 5 years. Additionally, a focus on a subgroup of patients younger than 50 years of age has demonstrated both superior outcomes in survival (91.6% survival at 1 year and 72.6% survival at 5 years) and decreased incidence of adverse events compared with older recipients. This younger cohort also demonstrated more tolerance to the characteristics of sex, race, ethnicity, and psychosocial indicators that are associated with worse outcomes after heart transplantation. Based upon these data, a potential net prolongation of life may be realized by considering prolonged left ventricular assist device support prior to heart transplantation in this population. These analyses provide preliminary data that could positively influence adoption of left ventricular assist device technology in groups previously not seen as candidates for this therapy, while providing a more responsible donor allocation strategy for advanced heart failure patients.

Cars pick up another passenger: Organ transplantation

With over 30,000 patients having received CAR T cells as a treatment for malignancy, our experience in oncology has facilitated numerous efforts to adapt the CAR therapeutic platform for diseases and conditions beyond cancer. Recognition of their efficacy, where traditional small molecule or biologic therapies fail, has spurred multiple efforts leveraging CAR T cells for immune modulation in the setting of organ/tissue transplantation. In the present review, we discuss CAR T cell approaches that are currently under development, to target both humoral and cellular alloimmunity. These include CAR T platforms repurposed from oncology and autoimmune diseases, as well as ones designed specifically to target alloimmunity in transplant. We also present important challenges and application considerations that will need to be addressed before we can expect successful clinical translation. Finally, we highlight a few of the exciting advances currently in development that are likely to pave a smoother path to translating CAR T cell therapies into transplant patients.

Collaborative care models in adult congenital heart disease transplant

PURPOSE OF REVIEW

While multidisciplinary collaboration is a tenant of quality heart failure care and critical to the success of transplant programs, this essay challenges the temptation to shoehorn adult congenital heart disease (ACHD) patients into preexisting processes and paradigms. We explore the development of more relevant models, purposefully designed to improve ACHD transplant volumes and outcomes.

RECENT FINDINGS

Globally, the rapid acceleration of ACHD patients living with and dying from HF stands in stark contrast to their access to transplant. Inferior early outcomes after ACHD transplant remain an undeniable barrier. And yet while all large registry datasets attest to this statistic, a few centers have achieved results comparable to those in acquired heart disease. This despite increases in both ACHD candidate complexity and referrals for Fontan Circulatory Failure. Perhaps something in their approach to care delivery is key?.

SUMMARY

Alone, neither ACHD nor transplant programs can provide optimal management of HF in ACHD. A siloed approach is similarly inadequate. Building new ACHD-HF-Transplant teams, centered on the patient and supplemented by ad hoc expert partnerships, is an exciting approach that can improve outcomes, create a high-quality training environment, and in our experience, is a truly rewarding way of working together.

Influence of Donor Transfusion on Heart Transplantation Outcomes: A United Network for Organ Sharing Registry Analysis

INTRODUCTION

There is a lack of evidence regarding the impact of donor blood transfusion on heart transplant (HT) outcomes. We sought to elucidate the influence of donor transfusion on HT outcomes using the national database.

METHODS

From January 2004 to March 2023, donor transfusion information was available for 40 538 recipients for HT in the United Network for Organ Sharing (UNOS) database. We used the UNOS 4-level designation of transfusion (no blood [N = 18 575], 1-5 units [N = 14 098], 6-10 units [N = 4766], and massive transfusion of > 10 units [N = 3099]).

RESULTS

Among this cohort, 53.2% of donors (N = 20 220) received a blood transfusion during the same admission. Donors who required blood transfusion commonly had head trauma as a cause of death (no-blood, 22% vs. 1-5 units, 61%, 6-10 units, 88%, massive, 89%, p < 0.001). An increased amount of donor blood transfusion did not affect rates of acute rejection (no-blood, 18% vs. 1-5 units, 19%, 6-10 units, 17%, massive, 19%, p = 0.13). The number of units transfused also did not affect 1-year survival rates. The Cox hazard model showed no effect of massive transfusion on mortality following transplant (no-blood, reference vs. 1-5 units; HR, 1.02 [p = 0.35], 6-10 units; HR, 1.10 [p = 0.01], massive transfusion; HR 1.04 [p = 0.3]).

CONCLUSIONS

Massive transfusion in donors was not associated with increased recipient mortality. Additionally, the amount of donor blood transfusion did not affect rejection rates following HT. The present study suggests that a history of donor blood transfusion, as well as the amount of transfusion, should not preclude donor heart utilization.

International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024

The "International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024" updates and replaces the "Listing Criteria for Heart Transplantation: International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates-2006" and the "2016 International Society for Heart Lung Transplantation Listing Criteria for Heart Transplantation: A 10-year Update." The document aims to provide tools to help integrate the numerous variables involved in evaluating patients for transplantation, emphasizing updating the collaborative treatment while waiting for a transplant. There have been significant practice-changing developments in the care of heart transplant recipients since the publication of the International Society for Heart and Lung Transplantation (ISHLT) guidelines in 2006 and the 10-year update in 2016. The changes pertain to 3 aspects of heart transplantation: (1) patient selection criteria, (2) care of selected patient populations, and (3) durable mechanical support. To address these issues, 3 task forces were assembled. Each task force was cochaired by a pediatric heart transplant physician with the specific mandate to highlight issues unique to the pediatric heart transplant population and ensure their adequate representation. This guideline was harmonized with other ISHLT guidelines published through November 2023. The 2024 ISHLT guidelines for the evaluation and care of cardiac transplant candidates provide recommendations based on contemporary scientific evidence and patient management flow diagrams. The American College of Cardiology and American Heart Association modular knowledge chunk format has been implemented, allowing guideline information to be grouped into discrete packages (or modules) of information on a disease-specific topic or management issue. Aiming to improve the quality of care for heart transplant candidates, the recommendations present an evidence-based approach.

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.

Impacts of Pre-transplant Panel-Reactive Antibody on Post-transplantation Outcomes: A Study of Nationwide Heart Transplant Registry Data

BACKGROUND AND OBJECTIVES

The number of sensitized heart failure patients on waiting lists for heart transplantation (HTx) is increasing. Using the Korean Organ Transplantation Registry (KOTRY), a nationwide multicenter database, we investigated the prevalence and clinical impact of calculated panel-reactive antibody (cPRA) in patients undergoing HTx.

METHODS

We retrospectively reviewed 813 patients who underwent HTx between 2014 and 2021. Patients were grouped according to peak PRA level as group A: patients with cPRA ≤10% (n= 492); group B: patients with cPRA >10%, <50% (n=160); group C patients with cPRA ≥50% (n=161). Post-HTx outcomes were freedom from antibody-mediated rejection (AMR), acute cellular rejection, coronary allograft vasculopathy, and all-cause mortality.

RESULTS

The median follow-up duration was 44 (19-72) months. Female sex, re-transplantation, and pre-HTx renal replacement therapy were independently associated with an increased risk of sensitization (cPRA ≥50%). Group C patients were more likely to have longer hospital stays and to use anti-thymocyte globulin as an induction agent compared to groups A and B. Significantly more patients in group C had positive flow cytometric crossmatch and had a higher incidence of preformed donor-specific antibody (DSA) compared to groups A and B. During follow-up, group C had a significantly higher rate of AMR, but the overall survival rate was comparable to that of groups A and B. In a subgroup analysis of group C, post-transplant survival was comparable despite higher preformed DSA in a desensitized group compared to the non-desensitized group.

CONCLUSIONS

Patients with cPRA ≥50% had significantly higher incidence of preformed DSA and lower freedom from AMR, but post-HTx survival rates were similar to those with cPRA <50%. Our findings suggest that sensitized patients can attain comparable post-transplant survival to non-sensitized patients when treated with optimal desensitization treatment and therapeutic intervention.

A modern heart transplant rejection surveillance protocol utilizing cell-free DNA: A single-center experience

BACKGROUND

Endomyocardial biopsy (EMBx) is considered the gold standard for rejection monitoring after heart transplantation; however, it is invasive and histologic interpretation has limitations. Sensitive blood biomarkers, including donor-derived cell-free DNA (dd-cfDNA), have emerged to decrease EMBx frequency.

METHODS

We retrospectively reviewed data on 237 patients who underwent heart transplantation at our institution. Of these, 125 patients underwent monitoring using dd-cfDNA, combined with a fewer number of EMBx, and 112 patients underwent monitoring using EMBx only. We compared rates of rejection, graft dysfunction, and survival at 1 year.

RESULTS

Median age at time of transplant was 59.8 years, and 77.6% were men. In the dd-cfDNA group, there were significantly fewer episodes of EMBx defined acute cellular rejection (ACR) (2.5% vs 18.8%, p < 0.001) and treated ACR (4.2% vs 19.6%, p = 0.001). Comparatively, there were more EMBx defined antibody-mediated rejection (AMR) (5% vs 0.9%) and treated AMR (5% vs 2.7%) in the dd-cfDNA group. No significant differences were observed in graft dysfunction, presence of donor-specific antibodies, or survival at 1 year.

CONCLUSIONS

In conclusion, a modern rejection surveillance protocol utilizing noninvasive testing is safe, led to significantly fewer EMBx, fewer treated rejection episodes, and no difference in survival at 1 year. More AMR episodes identified via dd-cfDNA could lead the way for more accurate diagnostic and treatment decisions.

Differences in Donor Heart Acceptance by Race and Gender of Patients on the Transplant Waiting List

Importance

Barriers to heart transplant must be overcome prior to listing. It is unclear why Black men and women remain less likely to receive a heart transplant after listing than White men and women.

Objective

To evaluate whether race or gender of a heart transplant candidate (ie, patient on the transplant waiting list) is associated with the probability of a donor heart being accepted by the transplant center team with each offer.

Design, Setting, and Participants

This cohort study used the United Network for Organ Sharing datasets to identify organ acceptance with each offer for US non-Hispanic Black (hereafter, Black) and non-Hispanic White (hereafter, White) adults listed for heart transplant from October 18, 2018, through March 31, 2023.

Exposures

Black or White race and gender (men, women) of a heart transplant candidate.

Main Outcomes and Measures

The main outcome was heart offer acceptance by the transplant center team. The number of offers to acceptance was assessed using discrete time-to-event analyses, nonparametrically (stratified by race and gender) and parametrically. The hazard probability of offer acceptance for each offer was modeled using generalized linear mixed models adjusted for candidate-, donor-, and offer-level variables.

Results

Among 159 177 heart offers with 13 760 donors, there were 14 890 candidates listed for heart transplant; 30.9% were Black, 69.1% were White, 73.6% were men, and 26.4% were women. The cumulative incidence of offer acceptance was highest for White women followed by Black women, White men, and Black men (P < .001). Odds of acceptance were less for Black candidates than for White candidates for the first offer (odds ratio [OR], 0.76; 95% CI, 0.69-0.84) through the 16th offer. Odds of acceptance were higher for women than for men for the first offer (OR, 1.53; 95% CI, 1.39-1.68) through the sixth offer and were lower for the 10th through 31st offers.

Conclusions and Relevance

The cumulative incidence of heart offer acceptance by a transplant center team was consistently lower for Black candidates than for White candidates of the same gender and higher for women than for men. These disparities persisted after adjusting for candidate-, donor-, and offer-level variables, possibly suggesting racial and gender bias in the decision-making process. Further investigation of site-level decision-making may reveal strategies for equitable donor heart acceptance.

Rapid desensitization through immunoadsorption during cardiopulmonary bypass. A novel method to facilitate human leukocyte antigen incompatible heart transplantation

BACKGROUND

Anti-human leukocyte antigen (HLA)-antibody production represents a major barrier to heart transplantation, limiting recipient compatibility with potential donors and increasing the risk of complications with poor waiting-list outcomes. Currently there is no consensus to when desensitization should take place, and through what mechanism, meaning that sensitized patients must wait for a compatible donor for many months, if not years. We aimed to determine if intraoperative immunoadsorption could provide a potential desensitization methodology.

METHODS

Anti-HLA antibody-containing whole blood was added to a Cardiopulmonary bypass (CPB) circuit set up to mimic a 20 kg patient undergoing heart transplantation. Plasma was separated and diverted to a standalone, secondary immunoadsorption system, with antibody-depleted plasma returned to the CPB circuit. Samples for anti-HLA antibody definition were taken at baseline, when combined with the CPB prime (on bypass), and then every 20 min for the duration of treatment (total 180 min).

RESULTS

A reduction in individual allele median fluorescence intensity (MFI) to below clinically relevant levels (<1000 MFI), and in the majority of cases below the lower positive detection limit (<500 MFI), even in alleles with a baseline MFI >4000 was demonstrated. Reduction occurred in all cases within 120 min, demonstrating efficacy in a time period usual for heart transplantation. Flowcytometric crossmatching of suitable pseudo-donor lymphocytes demonstrated a change from T cell and B cell positive channel shifts to negative, demonstrating a reduction in binding capacity.

CONCLUSIONS

Intraoperative immunoadsorption in an ex vivo setting demonstrates clinically relevant reductions in anti-HLA antibodies within the normal timeframe for heart transplantation. This method represents a potential desensitization technique that could enable sensitized children to accept a donor organ earlier, even in the presence of donor-specific anti-HLA antibodies.

Impact of age over 70 years in the new allocation system on the outcomes of heart transplantation in the US

BACKGROUND

United Network for Organ Sharing (UNOS) allocation criteria changed in 2018 to accommodate the increased prevalence of patients on a ventricular assist device as a bridge to heart transplant and prioritize sicker people in anticipation of a heart graft. We aimed to assess the impact of patient age in the new allocation policy on mortality following heart transplantation. Secondary outcomes included the effect of age ≥70 on post-transplant events, including stroke, dialysis, pacemaker, and rejection requiring treatment.

METHODS

The UNOS Registry was queried to identify patients who underwent heart transplants alone in the US between 2000 and 2021. Patients were divided into groups according to their age (over 70 and under 70 years old).

RESULTS

Patients aged over 70 were more likely to require dialysis during follow-up, but less likely to experience rejection requiring treatment, compared with patients aged <70. Age ≥70 in the new allocation system was a significant predictor of 1-year mortality (adjusted HR: 1.41; 95% CI: 1.05-1.91; p = .024), but its effect on 5-year mortality was not significant after adjusting for potential confounders (adjusted HR: 1.27; 95% CI:.97-1.66; p = .077). Undergoing transplantation under the new allocation policy vs the old allocation policy was not a significant predictor of mortality in patients over 70 years old.

CONCLUSIONS

Age ≥70 is a significant predictor of 1-year mortality following heart transplantation, but not at 5 and 10 years; however, the new allocation does not seem to have changed the outcomes for this group of patients.

HLA sensitization is associated with an increased risk of primary graft dysfunction after heart transplantation

Primary graft dysfunction (PGD) is a leading cause of early morbidity and mortality following heart transplantation (HT). We sought to determine the association between pretransplant human leukocyte antigen (HLA) sensitization, as measured using the calculated panel reactive antibody (cPRA) value, and the risk of PGD.

METHODS

Consecutive adult HT recipients (n = 596) from 1/2015 to 12/2019 at 2 US centers were included. Severity of PGD was based on the 2014 International Society for Heart and Lung Transplantation consensus statement. For each recipient, unacceptable HLA antigens were obtained and locus-specific cPRA (cPRA-LS) and pre-HT donor-specific antibodies (DSA) were assessed.

RESULTS

Univariable logistic modeling showed that peak cPRA-LS for all loci and HLA-A was associated with increased severity of PGD as an ordinal variable (all loci: OR 1.78, 95% CI: 1.01-1.14, p = 0.025, HLA-A: OR 1.14, 95% CI: 1.03-1.26, p = 0.011). Multivariable analysis showed peak cPRA-LS for HLA-A, recipient beta-blocker use, total ischemic time, donor age, prior cardiac surgery, and United Network for Organ Sharing status 1 or 2 were associated with increased severity of PGD. The presence of DSA to HLA-B was associated with trend toward increased risk of mild-to-moderate PGD (OR 2.56, 95% CI: 0.99-6.63, p = 0.053), but DSA to other HLA loci was not associated with PGD.

CONCLUSIONS

Sensitization for all HLA loci, and specifically HLA-A, is associated with an increased severity of PGD. These factors should be included in pre-HT risk stratification to minimize the risk of PGD.

Modern advances in heart transplantation

Heart transplantation (HTx) is the only definitive therapy for patients with end stage heart disease. With the increasing global prevalence of heart failure, the demand for HTx has continued to grow and outpace supply. In this paper, we will review advances in the field of HTx along the clinical journey of a HTx recipient. Starting with the sensitized patient, we discuss current methods to define sensitization, and assays to help identify clinically relevant anti-HLA antibodies. Desensitization strategies targeting all levels of the adaptive immune system are discussed with emphasis on novel techniques such as anti-CD 38 blockade and use of the Immunoglobulin G-Degrading Enzyme of Streptococcus Pyogenes. We next discuss donor procurement and the resurgence of donation after circulatory death as a viable strategy to significantly and safely increase the donor pool. Post-transplant, we evaluate non-invasive surveillance techniques including gene expression profiling and donor-derived cell-free DNA. Last, we discuss the ground-breaking developments in the field of xenotransplantation.

Rejection Requiring Treatment within the First Year following Heart Transplantation: The UNOS Insight

(1) Background: Heart failure is an extremely impactful health issue from both a social and quality-of-life point of view and the rate of patients with this condition is destined to rise in the next few years. Transplantation remains the mainstay of treatment for end-stage heart failure, but a shortage of organs represents a significant problem that prolongs time spent on the waiting list. In view of this, the selection of donor and recipient must be extremely meticulous, considering all factors that could predispose to organ failure. One of the main considerations regarding heart transplants is the risk of graft rejection and the need for immunosuppression therapy to mitigate that risk. In this study, we aimed to assess the characteristics of patients who need immunosuppression treatment for rejection within one year of heart transplantation and its impact on mid-term and long-term mortality. (2) Methods: The United Network for Organ Sharing (UNOS) Registry was queried to identify patients who solely underwent a heart transplant in the US between 2000 and 2021. Patients were divided into two groups according to the need for anti-rejection treatment within one year of heart transplantation. Patients' characteristics in the two groups were assessed, and 1 year and 10 year mortality rates were compared. (3) Results: A total of 43,763 patients underwent isolated heart transplantation in the study period, and 9946 (22.7%) needed anti-rejection treatment in the first year. Patients who required treatment for rejection within one year after transplant were more frequently younger (49 ± 14 vs. 52 ± 14 years, p < 0.001), women (31% vs. 23%, p < 0.001), and had a higher CPRA value (14 ± 26 vs. 11 ± 23, p < 0.001). Also, the rate of prior cardiac surgery was more than double in this group (27% vs. 12%, p < 0.001), while prior LVAD (12% vs. 11%, p < 0.001) and IABP (10% vs. 9%, p < 0.01) were more frequent in patients who did not receive anti-rejection treatment in the first year. Finally, pre-transplantation creatinine was significantly higher in patients who did not need treatment for rejection in the first year (1.4 vs. 1.3, p < 0.01). Most patients who did not require anti-rejection treatment underwent heart transplantation during the new allocation era, while less than half of the patients who required treatment underwent transplantation after the new allocation policy implementation (65% vs. 49%, p < 0.001). Patients who needed rejection treatment in the first year had a higher risk of unadjusted 1 year (HR: 2.25; 95% CI: 1.88-2.70; p < 0.001), 5 year (HR: 1.69; 95% CI: 1.60-1.79; p < 0.001), and 10 year (HR: 1.47; 95% CI: 1.41-1.54, p < 0.001) mortality, and this was confirmed at the adjusted analysis at all three time-points. (4) Conclusions: Medical treatment of acute rejection was associated with significantly increased 1 year mortality compared to patients who did not require anti-rejection therapy. The higher risk of mortality was confirmed at a 10 year follow-up. Further studies and newer follow-up data are required to investigate the role of anti-rejection therapy in the heart transplant population.

Immunotherapy targeting B cells and long-lived plasma cells effectively eliminates pre-existing donor-specific allo-antibodies

Pre-existing anti-human leukocyte antigen (HLA) allo-antibodies constitute a major barrier to transplantation. Current desensitization approaches fail due to ineffective depletion of allo-specific memory B cells (Bmems) and long-lived plasma cells (LLPCs). We evaluate the efficacy of chimeric antigen receptor (CAR) T cells targeting CD19 and B cell maturation antigen (BCMA) to eliminate allo-antibodies in a skin pre-sensitized murine model of islet allo-transplantation. We find that treatment of allo-sensitized hosts with CAR T cells targeting Bmems and LLPCs eliminates donor-specific allo-antibodies (DSAs) and mitigates hyperacute rejection of subsequent islet allografts. We then assess the clinical efficacy of the CAR T therapy for desensitization in patients with multiple myeloma (MM) with pre-existing HLA allo-antibodies who were treated with the combination of CART-BCMA and CART-19 (ClinicalTrials.gov: NCT03549442) and observe clinically meaningful allo-antibody reduction. These findings provide logical rationale for clinical evaluation of CAR T-based immunotherapy in highly sensitized candidates to promote successful transplantation.

Reduction of HLA donor specific antibodies in heart transplant patients treated with proteasome inhibitors for antibody mediated rejection

In this project, we describe proteasome inhibitor (PI) treatment of antibody-mediated rejection (AMR) in heart transplantation (HTX). From January 2018 to September 2021, 10 patients were treated with PI for AMR: carfilzomib (CFZ) n = 8; bortezomib (BTZ) n = 2. Patients received 1-3 cycles of PI. All patients had ≥1 strong donor-specific antibody (DSA) (mean fluorescence intensity [MFI] > 8000) in undiluted serum. Most DSAs (20/21) had HLA class II specificity. The MFI of strong DSAs had a median reduction of 56% (IQR = 13%-89%) in undiluted serum and 92% (IQR = 53%-95%) at 1:16 dilution. Seventeen DSAs in seven patients were reduced > 50% at 1:16 dilution after treatment. Four DSAs from three patients did not respond. DSA with MFI > 8000 at 1:16 dilution was less responsive to treatment. 60% (6/10) patients presented with graft dysfunction; 4/6 recovered ejection fraction > 40% after treatment. Pathologic AMR was resolved in 5/7 (71.4%) of patients within 1 year after treatment. 9/10 (90%) patients survived to 1 year after AMR diagnosis. Using PI in AMR resulted in significant DSA reduction with some resolution of graft dysfunction. Larger studies are needed to evaluate PI for AMR.

BSHI and BTS UK guideline on the detection of alloantibodies in solid organ (and islet) transplantation

Solid organ transplantation represents the best (and in many cases only) treatment option for patients with end-stage organ failure. The effectiveness and functioning life of these transplants has improved each decade due to surgical and clinical advances, and accurate histocompatibility assessment. Patient exposure to alloantigen from another individual is a common occurrence and takes place through pregnancies, blood transfusions or previous transplantation. Such exposure to alloantigen's can lead to the formation of circulating alloreactive antibodies which can be deleterious to solid organ transplant outcome. The purpose of these guidelines is to update to the previous BSHI/BTS guidelines 2016 on the relevance, assessment, and management of alloantibodies within solid organ transplantation.

Association between calculated panel reactive antibody and waitlist outcomes in the 2018 heart allocation system

BACKGROUND

The impact of heart transplant (HT) waitlist candidate sensitization on waitlist outcomes in the US is unknown.

METHODS

Adult waitlist outcomes in OPTN (October 2018-September 2022) by calculated panel reactive antibody (cPRA) were modeled to identify thresholds of clinical significance. The primary outcome was the rate of HT by cPRA category (low: 0-35, middle: >35-90, high: >90) assessed using multivariable competing risk analysis (compete: waitlist removal for death or clinical deterioration). The secondary outcome was waitlist removal for death or clinical deterioration.

RESULTS

The elevated cPRA categories were associated with lower rates of HT. Candidates in the middle (35-90) and high cPRA categories (>90) had an adjusted 24% lower rate (hazard ratio (HR) 0.86, 95% confidence interval (CI) 0.80-0.92) and 61% lower rate (HR 0.39 95% CI. 0.33-0.47) of HT than the lowest category, respectively. Waitlist candidates in the high cPRA category listed in the top acuity strata (Statuses 1, 2) had increased rates of delisting for death or deterioration compared to those in the low cPRA category (adjusted HR 2.9, 95% CI 1.5-5.5), however, elevated cPRA (middle, high) was not associated with an increased rate of death and delisting when the cohort was considered as a whole.

CONCLUSIONS

Elevated cPRA was associated with reduced rates of HT across all waitlist acuity tiers. Among HT waitlist candidates listed at the top acuity strata, the high cPRA category was associated with increased rates of delisting due to death or deterioration. Elevated cPRA may require consideration for critically ill candidates under continuous allocation.

Management of the sensitized heart transplant candidate

PURPOSE OF REVIEW

For sensitized heart transplant candidates who have antibodies to human leukocyte antigens (HLA), finding a suitable donor can be challenging and can lead to adverse waitlist outcomes. In recent years, the number of sensitized patients awaiting heart transplantation has increased likely due to the use of durable and mechanical circulatory support as well as increasing number of candidates with underlying congenital heart disease.

RECENT FINDINGS

Advances in the assessment of HLA antibodies allow for identification of heart transplant candidates who may benefit from desensitization strategies to widen the donor pool and mitigate the risk of adverse posttransplant outcomes.

SUMMARY

Antibody sensitization is a barrier to successful heart transplantation and strategies to identify sensitized patients, stratify their risk, and mitigate this risk through desensitization is crucial to optimize the quality of life and survival of HT recipients.

Three year post heart transplant outcomes of desensitized durable mechanical circulatory support patients

BACKGROUND

The risks and benefits of desensitization therapy (DST) in highly sensitized mechanical circulatory support (MCS) patients are not well known. We investigated 3 year post-transplant outcomes of desensitized durable MCS patients.

METHODS

Among 689 consecutively enrolled heart transplantation recipients between 2010 and 2016, we categorized them into Group A (desensitized MCS patients, n = 21), Group B (desensitized non-MCS patients, n = 28) and Group C (all nondesensitized patients, n = 640). Post-transplant outcomes included the incidence of primary graft dysfunction, 3-year survival, freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, any treated rejection, acute cellular rejection, antibody mediated rejection (AMR) and infectious complications.

RESULTS

The types of DST in Groups A and B were similar and included combinations of rituximab/intravenous immunoglobulin and plasmapheresis/bortezomib. Group A, compared with Group B, showed significantly higher pre-DST panel reactive antibody (PRA) (92.2 ± 9.8 vs. 83.3 ± 15.6, P = 0.007) and higher PRA reduction after DST (-22.2 ± 26.9 vs. -6.3 ± 7.5, P = 0.015). Groups A and C showed comparable primary graft dysfunction, 3-year survival, freedom from cardiac allograft vasculopathy, nonfatal major adverse cardiac events, any treated rejection, acute cellular rejection, and AMR. Although statistically not significant, Group A showed numerically higher 3-year freedom from AMR than Group B. Infectious complications were similar in both Groups A and B.

CONCLUSIONS

DST for MCS patients showed significant PRA reduction, resulting in an expansion of the donor pool. The post-transplant outcome of desensitized MCS patients showed comparable clinical outcomes to non-desensitized control patients in the same study period, revealing the safety and efficacy of DST.

Lung transplantation in an 18-month-old with donor specific antibodies - The use of intraoperative, targeted plasma exchange

BACKGROUND

Sensitised patients undergoing Human Leukocyte Antigen-incompatible transplantation are at increased risk of hyperacute rejection and may be predisposed to antibody-mediated rejection, chronic lung allograft dysfunction and higher mortality.

CASE

We present a case of primary lung transplantation in the setting of late identification of donor specific antibodies treated with intraoperative target plasma exchange. The patient was treated with fresh human plasma to a final volume of 1.5 times the patient's systemic circulation. From a pre-transplant mean fluorescence intensity of 5002, donor-specific antibodies were undetectable following plasma exchange on single antigen bead assay.

CONCLUSIONS

This method represents a potential desensitisation technique for use in the intraoperative period.

Outcomes of Patients Undergoing Combined Heart-Kidney Transplantation With or Without Prior Ventricular Assist Device

BACKGROUND

Both combined heart-kidney transplantation and ventricular assist devices (VADs) pose significant challenges, including sensitization, immunosuppressive treatment, and infrastructure demands. Despite these challenges, we hypothesized that the recipients of combined heart-kidney transplants with and without VADs would have equivalent survival. We aimed to compare the survival of heart-kidney transplant recipients with and without prior VAD placement.

METHODS

We retrospectively analyzed all patients enrolled in the United Network for Organ Sharing database who underwent heart-kidney transplants. We created a matched cohort of patients undergoing heart-kidney transplantation with or without prior VAD using 1:1 nearest propensity-score matching with preoperative variables.

RESULTS

In the propensity-matched cohort, 399 patients underwent heart-kidney transplantation with prior VAD, and 399 underwent heart-kidney transplantation without prior VAD. The estimated survival of heart--kidney recipients with prior VAD was 84.8% at one year, 81.2% at 3 years, and 75.3% at 5 years. The estimated survival of heart-kidney recipients without prior VAD was 86.8.7% at one year, 84.0% at 3 years, and 78.8% at 5 years. There was no statistically significant difference in the survival of heart-kidney transplant recipients with or without prior VAD at one year (P = .42; Figure 2), 3 years (P = .34), or 5 years (P = .30).

CONCLUSION

Despite the increased challenge of heart-kidney transplantation in recipients with prior VAD, we demonstrated that these patients have similar survival to those who underwent heart-kidney transplantation without previous VAD placement.

Detection and management of HLA sensitization in candidates for adult heart transplantation

Heart transplantation (HT) remains the preferred therapy for patients with advanced heart failure. However, for sensitized HT candidates who have antibodies to human leukocyte antigens , finding a suitable donor can be challenging and can lead to adverse waitlist outcomes. In recent years, the number of sensitized patients awaiting HT has increased likely due to the use of durable and mechanical circulatory support as well as increasing number of candidates with underlying congenital heart disease. This State-of-the-Art review discusses the assessment of human leukocyte antigens antibodies, potential desensitization strategies including mechanisms of action and specific protocols, the approach to a potential donor including the use of complement-dependent cytotoxicity, flow cytometry, and virtual crossmatches, and peritransplant induction management.

The End of Endomyocardial Biopsy?: A Practical Guide for Noninvasive Heart Transplant Rejection Surveillance

Noninvasive heart transplant rejection surveillance using gene expression profiling (GEP) to monitor immune activation is widely used among heart transplant programs. With the new development of donor-derived cell-free DNA (dd-cfDNA) assays, more programs are transitioning to a predominantly noninvasive rejection surveillance protocol with a reduced frequency of endomyocardial biopsies. As a result, many practical questions arise that potentially delay implementation of these valuable new tools. The purpose of this review is to provide practical guidance for clinicians transitioning toward a less invasive acute rejection monitoring protocol after heart transplantation, and to answer 10 common questions about the GEP and dd-cfDNA assays. Evidence supporting GEP and dd-cfDNA testing is reviewed, as well as guidance on test interpretation and future directions.

Antibody-Mediated Rejection: Diagnosis and Treatment

Antibody-mediated rejection (AMR) is a form of lung allograft rejection that is emerging as an important risk factor for chronic lung allograft dysfunction and decreased long-term survival. In this review, we provide a brief overview of our current understanding of its pathophysiology with an emphasis on donor-specific antibodies before moving on to focus on the current diagnostic criteria and treatment strategies. Our goal is to discuss the limitations of our current knowledge and explore how novel diagnostic and therapeutic options aim to improve outcomes through earlier definitive diagnosis and preemptive targeted treatment.

Addressing sex-based disparities in solid organ transplantation in the United States - a conference report

Solid organ transplantation provides the best treatment for end-stage organ failure, but significant sex-based disparities in transplant access exist. On June 25, 2021, a virtual multidisciplinary conference was convened to address sex-based disparities in transplantation. Common themes contributing to sex-based disparities were noted across kidney, liver, heart, and lung transplantation, specifically the existence of barriers to referral and wait listing for women, the pitfalls of using serum creatinine, the issue of donor/recipient size mismatch, approaches to frailty and a higher prevalence of allosensitization among women. In addition, actionable solutions to improve access to transplantation were identified, including alterations to the current allocation system, surgical interventions on donor organs, and the incorporation of objective frailty metrics into the evaluation process. Key knowledge gaps and high-priority areas for future investigation were also discussed.

Impact of the 2018 UNOS Heart Transplant Policy Changes on Patient Outcomes

In 2018, the United Network for Organ Sharing implemented a 6-tier allocation policy to replace the prior 3-tier system. Given increasing listings of critically ill candidates for heart transplantation and lengthening waitlist times, the new policy aimed to better stratify candidates by waitlist mortality, shorten waiting times for high priority candidates, add objective criteria for common cardiac conditions, and further broaden sharing of donor hearts. There have been significant shifts in cardiac transplantation practices and patient outcomes following the implementation of the new policy, including changes in listing practices, waitlist time and mortality, transplant donor characteristics, post-transplantation outcomes, and mechanical circulatory support use. This review aims to highlight emerging trends in United States heart transplantation practice and outcomes following the implementation of the 2018 United Network for Organ Sharing heart allocation policy and to address areas for future modification.

Basiliximab induction versus no induction in adult heart transplantation

BACKGROUND

Induction immunosuppression in heart transplant recipients varies greatly by center. Basiliximab (BAS) is the most commonly used induction immunosuppressant but has not been shown to reduce rejection or improve survival. The objective of this retrospective study was to compare rejection, infection, and mortality within the first 12 months following heart transplant in patients who received BAS or no induction.

METHODS

This was a retrospective cohort study of adult heart transplant recipients given BAS or no induction from January 1, 2017 to May 31, 2021. The primary endpoint was incidence of treated acute cellular rejection (ACR) at 12-months post-transplant. Secondary endpoints included ACR at 90 days post-transplant, incidence of antibody-mediated rejection (AMR) at 90 days and 1 year, incidence of infection, and all-cause mortality at 1 year.

RESULTS

A total of 108 patients received BAS, and 26 patients received no induction within the specified timeframe. There was a lower incidence of ACR within the first year in the BAS group compared to the no induction group (27.7 vs. 68.2%, p < .002). BAS was independently associated with a lower probability of having a rejection event during the first 12-months post-transplant (hazard ratio (HR) .285, 95% confidence interval [CI] .142-.571, p < .001). There was no difference in the rate of infection and in mortality after hospital discharge at 1-year post-transplant (6% vs. 0%, p = .20).

CONCLUSION

BAS appears to be associated with greater freedom from rejection without an increase in infections. BAS may be a preferred to a no induction strategy in patients undergoing heart transplantation.

Donor specific antibodies association with survival and adverse events after heart transplantation: A single center retrospective study between 2006 and 2021

OBJECTIVE

Newly detected donor HLA-specific antibodies (DSA) are historically known to be associated with reduced survival in heart transplant patients. Our objective is to clarify the modern incidence of DSA and determine its relationship with survival and MACE.

METHODS

This retrospective study included all patients undergoing orthotopic heart transplantation at Harefield Hospital, London between January 1, 2006 and May 31, 2021. We identified patients who developed DSA at any point post heart transplantation and its effect on survival and MACE (defined as rejection, coronary event, stroke, and arrhythmia.

RESULTS

In total of 232 patients were included with a median follow up time of 4.7 years post heart transplantation. 23.7% of patients included developed DSA post heart transplantation. There was a significantly increased risk of death in patients developing DSA versus not (sub distribution hazard ratio [SHR] 1.83, 95% confidence interval 1.03-3.24, p = .04). At the time of detection of DSA, 38.2% of the cohort had rejection necessitating treatment. A MACE event had occurred in 48.1% by 2 years and 53.7% by 3 years in the DSA cohort. There was a significantly increased risk of MACE in patients developing DSA versus not (SHR 2.48 [1.58-3.89, p < .0001]).

CONCLUSIONS

This study showed an increased risk of death and MACE in patients developing DSA post heart transplantation. Further research is required into the optimal management of these patients.

Review of Postoperative Care for Heart Transplant Recipients

The early postoperative management strategies after heart transplantation include optimizing the function of the denervated heart, correcting the causes of hemodynamic instability, and initiating and maintaining immunosuppressive therapy, allograft rejection surveillance, and prophylaxis against infections caused by immunosuppression. The course of postoperative support is influenced by the quality of allograft myocardial protection prior to implantation and reperfusion, donor-recipient heart size matching, surgical technique of orthotopic heart transplantation, and patient factors (eg, preoperative condition, immunologic compatibility, postoperative vasomotor tone, severity and reversibility of pulmonary vascular hypertension, pulmonary function, mediastinal blood loss, and end-organ perfusion). This review provides an overview of the early postoperative care of recipients and includes a brief description of the surgical techniques for orthotopic heart transplantation.

Elevated Plasma Immunoglobulin Levels Prior to Heart Transplantation Are Associated with Poor Post-Transplantation Survival

Cardiac allograft vasculopathy (CAV) and antibody-mediated rejection are immune-mediated, long-term complications that jeopardize graft survival after heart transplantation (HTx). Interestingly, increased plasma levels of immunoglobulins have been found in end-stage heart failure (HF) patients prior to HTx. In this study, we aimed to determine whether increased circulating immunoglobulin levels prior to transplantation are associated with poor post-HTx survival. Pre-and post-HTx plasma samples of 36 cardiac transplant recipient patients were used to determine circulating immunoglobulin levels. In addition, epicardial tissue was collected to determine immunoglobulin deposition in cardiac tissue and assess signs and severity of graft rejection. High levels of IgG1 and IgG2 prior to HTx were associated with a shorter survival post-HTx. Immunoglobulin deposition in cardiac tissue was significantly elevated in patients with a survival of less than 3 years. Patients with high plasma IgG levels pre-HTx also had significantly higher plasma levels after HTx. Furthermore, high pre-HTX levels of IgG1 and IgG2 levels were also significantly increased in patients with inflammatory infiltrate in CAV lesions. Altogether the results of this proof-of-concept study suggest that an activated immune response prior to transplantation negatively affects graft survival.

Comparing left ventricular assist device inflow cannula angle between median sternotomy and thoracotomy using 3D reconstructions

BACKGROUND

Left ventricular assist device (LVAD) implantation via thoracotomy has many potential advantages compared to conventional sternotomy, including improved inflow cannula (IFC) positioning. We compared the difference in IFC angles, postoperative, and long-term outcomes for patients with LVADs implanted via thoracotomy and sternotomy.

METHODS

A single-center, retrospective analysis of 14 patients who underwent thoracotomy implantation was performed and matched with 28 patients who underwent sternotomy LVAD implantations for a total of 42 patients. Inclusion required a minimum LVAD support duration of 30 days and excluded concomitant procedures. A postoperative CT-chest was used to measure the angle the between the IFC and mitral valve in two-dimensions and results were compared with three-dimensional reconstruction using the same CT chest. Outcome data were extracted from medical records.

RESULTS

There was no significant difference in gender, INTERMACS score, BMI, or age between the two groups. Median cardiopulmonary bypass time was longer in the thoracotomy group compared to the sternotomy group, 107 min (86-122) versus 76 min (56-93), p < 0.01. 3D reconstructions revealed less deviation of the IFC away from the mitral valve in devices implanted via thoracotomy compared to sternotomy, median (IQR) angle 16.3° (13.9°-21.0°) versus 23.2° (17.9°-26.4°), p < 0.01. Rates of pump thrombosis, stroke, and gastrointestinal bleeding were not significantly different.

CONCLUSIONS

Devices implanted via thoracotomy demonstrated less deviation away from mitral valve. However, there was no difference in morbidity between the two approaches. 3D reconstruction of the heart is an innovative technique to measure angulation and is clinically advantageous when compared to 2D imaging.

Outcomes of Cardiac Transplantation in Western Australia - A Contemporary Single Centre Experience

BACKGROUND

Cardiac transplantation remains the gold standard therapy for select patients with end-stage heart failure and outcomes have improved significantly over the past few decades. We report the 5-year contemporary experience of cardiac transplantation in Western Australia, one of the most remote transplant centres worldwide.

METHODS

Patients undergoing isolated cardiac transplant at Fiona Stanley Hospital (FSH) from February 2015 until April 2021 were included. Donor details were collected using donor electronic records (Donate Life, Australia). Recipient data was collated from electronic medical records at FSH and the Australia and New Zealand Society of Cardiothoracic Surgery database. The primary outcome measure was all-cause mortality. Secondary outcome measures included postoperative intensive care and total hospital length of stay and rates of acute kidney injury, rejection, serious infections, and cardiac allograft vasculopathy. Frailty indices were also assessed.

RESULTS

A total of 60 patients were included (mean age 53±14 yrs, 66.7% male). The commonest indication for transplant was a non-ischaemic cardiomyopathy (46.7%). Mean donor age was 35±12 years and median donor ischaemia time was 171 minutes (IQR=138-240). After median follow-up of 3.7 years, there were no mortalities. Postoperative renal failure occurred in 21 (35.0%) patients, pneumonia in four (6.7%), deep sternal wound infection in three (5.1%), acute rejection in 17 (28.3%) and cardiac allograft vasculopathy (CAV) in 23 (38.3%).

CONCLUSION

With recipient and donor criteria comparable to national and international standards, compounded by the challenges of geographic isolation, we report the first published data on contemporary outcomes post isolated cardiac transplantation in Western Australia.

Case report: Successful simultaneous heart-kidney transplantation across a positive complement-dependent cytotoxic crossmatch

Preformed donor-specific antibodies are associated with a higher risk of rejection and worse graft survival in organ transplantation. However, in heart transplantation, the risk and benefit balance between high mortality on the waiting list and graft survival may allow the acceptance of higher immunologic risk donors in broadly sensitized recipients. Transplanting donor-recipient pairs with a positive complement dependent cytotoxic (CDC) crossmatch carries the highest risk of hyperacute rejection and immediate graft loss and is usually avoided in kidney transplantation. Herein we report the first successful simultaneous heart-kidney transplant with a T- and B-cell CDC crossmatch positive donor using a combination of rituximab, intravenous immunoglobulin, plasmapheresis, bortezomib and rabbit anti-thymocyte globulin induction followed by eculizumab therapy for two months post-transplant. In the year following transplantation, both allografts maintained stable graft function (all echocardiographic left ventricular ejection fractions ≥ 65%, eGFR>60) and showed no histologic evidence of antibody-mediated rejection. In addition, the patient has not developed any severe infections including cytomegalovirus or BK virus infection. In conclusion, a multitarget immunosuppressive regimen can allow for combined heart/kidney transplantation across positive CDC crossmatches without evidence of antibody-mediated rejection or significant infection. Longer follow-up will be needed to further support this conclusion.

Preoperative Evaluation and Care of Heart Transplant Candidates

Heart transplantation is recommended for patients with advanced heart failure refractory to medical and device therapy, and who do not have absolute contraindications. When patients become eligible for heart transplantation, they undergo comprehensive evaluation and preparation to optimize their posttransplantation outcomes. This review provides an overview of the processes that are employed to enable the candidates to be transplant-ready when donor hearts are available.

Sex differences in patients undergoing heart transplantation and LVAD therapy

INTRODUCTION

Left ventricular assist device (LVAD) and heart transplantation (HT) are the two life-sustaining therapies that have revolutionized the management of end-stage heart failure (HF). Yet, significant sex differences exist with respect to their use and effects.

AREAS COVERED

This review summarizes sex differences in the utilization, outcomes, and complications of LVAD and HT. Particular emphasis is placed on leading clinical trials in the field, historical and recent large registries-based analyses, as well as contemporary technological and policy changes affecting these differences.

EXPERT OPINION

Women with advanced HF remain under-treated with guideline-directed medical therapy and are less likely to be referred for consideration for LVAD and HT. This remains true despite newer LVAD technology and the new heart transplant allocation system. Community outreach, education, as well as increased representation of women in clinical research may reduce inequities.

Pig heart and lung xenotransplantation: Present status

The recent pig heart transplant in a patient at the University of Maryland Medical Center has stimulated renewed interest in the xenotransplantation of organs from genetically engineered pigs. The barriers to the use of pigs as sources of organs have largely been overcome by 2 approaches - (1) the deletion of expression of the three known pig carbohydrate xenoantigens against which humans have preformed antibodies, and (2) the transgenic introduction of human 'protective' proteins, such as complement-regulatory proteins. These gene modifications, coupled with immunosuppressive therapy based on blockade of the CD40/CD154 costimulation pathway, have resulted in survival of baboons with life-supporting pig heart grafts for almost 9 months. The initial clinical success at the University of Maryland reinforces encouraging preclinical results. It suggests that pig hearts are likely to provide an effective bridge to an allotransplant, but their utility for destination therapy remains uncertain. Because of additional complex immunobiological problems, the same approach has been less successful in preclinical lung xenograft transplantation, where survival is still measured in days or weeks. The first formal clinical trials of pig heart transplantation may include patients who do not have access to an allotransplant, those with contraindications for mechanical circulatory support, those in need of retransplantation or with a high level of panel-reactive antibodies. Infants with complex congenital heart disease, should also be considered.

Heart transplantation across preformed donor-specific antibody barriers using a perioperative desensitization protocol

Heart transplantation across preformed donor-specific HLA-antibody barriers is associated with impaired short- and long-term survival. Therefore, in recipients with preformed anti-HLA antibodies, waiting for crossmatch-negative donors is standard practice. As an alternative strategy, recipients with preformed anti-HLA donor specific antibodies have been managed at our institutions with a perioperative desensitization regimen. A retrospective analysis was performed comparing heart transplant recipients with preformed donor-specific HLA-antibodies to recipients without donor-specific antibodies. Recipients with a positive virtual crossmatch received a perioperative desensitization protocol including tocilizumab intraoperatively, plasma exchange and rituximab followed by a six-month course of IgGAM. Among the 117 heart-transplanted patients, 19 (16%) patients underwent perioperative desensitization, and the remaining 98 (84%) patients did not. Cold ischemic time, posttransplant extracorporeal life support for primary graft dysfunction, and intensive care unit stay time did not differ between groups. At 1-year follow-up, freedom from pulsed steroid therapy for presumed rejection and biopsy-confirmed acute cellular or humoral rejection did not differ between groups. One-year survival amounted to 94.7% in the treated patients and 81.4% in the control group. Therefore, heart transplantation in sensitized recipients undergoing a perioperative desensitization appears safe with comparable postoperative outcomes as patients with a negative crossmatch.

The Assessment and Outcomes of Crossmatching in Lung Transplantation in Korean Patients

BACKGROUND

In lung transplantation, human leukocyte antigen (HLA) compatibility is not included in the lung allocation score system or considered when placing donor allografts. However, HLA matching may affect the outcomes of lung transplantation. This study evaluated the current assessment status, prevalence, and effects of HLA crossmatching in lung transplantation in Korean patients using nationwide multicenter registry data.

METHODS

Two hundred and twenty patients who received lung transplantation at six tertiary hospitals in South Korea between March 2015 and December 2019 were retrospectively reviewed. Clinical data, including general demographic characteristics, primary diagnosis, and pretransplant status of the recipients and donors registered by the Korean Organ Transplant Registry, were retrospectively analyzed. Survival analysis was performed using the Kaplan-Meier method with log-rank tests.

RESULTS

Complement-dependent cytotoxic crossmatch (CDC-XM) was performed in 208 patients (94.5%) and flow cytometric crossmatch (flow-XM) was performed in 125 patients (56.8%). Among them, nine patients (4.1%) showed T cell- and/or B cell-positive crossmatches. The incidences of postoperative complications, including primary graft dysfunction, acute rejection, and chronic allograft dysfunction in positively crossmatched patients, were not significant compared with those in patients without mismatches. Moreover, Kaplan-Meier analyses showed poorer 1-year survival in patients with positive crossmatch according to CDC-XM (P < 0.001) and T lymphocyte XM (P = 0.002) than in patients without mismatches.

CONCLUSION

Positive CDC and T lymphocyte crossmatching results should be considered in the allocation of donor lungs. If unavailable, the result should be considered for postoperative management in lung transplantation.

The role of sensitization in post-transplant outcomes in adults with congenital heart disease sensitization in adults with congenital heart disease

Introduction

The number of heart transplants in adults with congenital heart disease (CHD) is increasing, though outcomes remain unfavorable compared to those without CHD. The etiology of this mortality difference remains uncertain. Panel reactive antibody (PRA) is a predictor of survival post-transplantation, and adult CHD patients have been observed to have higher PRA levels. Here we assessed the relationship between PRA and outcomes in adult patients with CHD who underwent heart transplantation.

Methods

This is a retrospective cohort study using the 2004-2015 ISHLT Thoracic Organ Transplant Registry to investigate the role of sensitization in the observed excess mortality. The composite outcome of mortality or graft failure within 1-year of transplantation was compared among CHD vs. non-CHD recipients, according to sensitization as measured by pre-transplant panel reactive antibodies (PRA).

Results

Adults with CHD (n = 1188) had higher PRA level compared to non-CHD (n = 38,201) recipients (27% vs. 18% PRA>10%, respectively, p < 0.001). CHD diagnosis remained independently associated with a higher incidence of the composite outcome in multivariable analysis after adjusting for PRA and other variables. Further, even after age-matching, patients with CHD and PRA ≤10% were at higher risk of the primary outcome compared to non-CHD (OR 2.1 [1.4-3.4], p = 0.001), though both groups had comparable outcomes when PRA was >10% (OR 1.1 [0.6-2.0], p = 0.852).

Conclusions

Adults with CHD are more likely to have higher sensitization and worse outcomes than non-CHD recipients. Higher sensitization rates alone do not fully explain their excess risk of adverse outcomes after heart transplantation.

Sternum-Sparing Left Ventricular Assist Device Insertion Reduces Perioperative Transfusions and Blood Loss: A Single-Centre Canadian Experience

Background

Left ventricular assist devices (LVADs) improve survival and quality of life, as either destination therapy or a bridge to transplantation. Although less-invasive hemisternotomy approaches for LVAD implantation are well studied, only a paucity of data is available in the literature on sternum-sparing bilateral minithoracotomy (BMT). Our centre has one of Canada’s most extensive experiences with the BMT approach. Herein, we compared LVAD implantation via BMT with patients who received full median sternotomy or hemisternotomy.

Methods

A single-centre retrospective review of data from Foothills Medical Centre (Calgary, Canada) was performed. Patients underwent LVAD insertion from 2012 to 2019, receiving either BMT (n = 11) or sternotomy (full median sternotomy or upper hemisternotomy with left minithoracotomy; n = 38). Intraoperative and early postoperative outcomes were assessed.

Results

Patients who received BMT had significantly fewer transfusions of red blood cells, fresh frozen plasma, and platelets. The BMT group had lower chest-tube output in the first 12 hours. No significant differences occurred in ventilation time, intensive care unit length of stay, mortality, stroke, or reoperation for bleeding.

Conclusions

Outcomes suggest that sternum-sparing LVAD implantation is a feasible alternative to sternotomy, leading to less postoperative blood loss and transfusion in the early postoperative period. Less transfusion is particularly valuable in this patient population, to reduce antigen-related sensitization prior to transplantation. Additional study is needed to assess potential benefits related to right heart function, postoperative mobility, and re-entry for transplantation.

Association between homograft tissue exposure and allosensitization prior to heart transplant in patients with congenital heart disease

BACKGROUND

Surgical repair for patients with congenital heart disease (CHD) often incorporates homograft tissue or other foreign material that can lead to allosensitization. We sought to identify the relationship between pre-sensitization prior to heart transplant and exposure to homograft tissue in CHD patients.

METHODS

Retrospective chart review of all CHD patients who underwent heart transplant at a major pediatric transplant center between 1/1/2011-3/31/18. Operative records determined use of homograft tissue or foreign material. Panel reactive antibody (PRA) and Luminex^TM single-antigen bead (SAB) testing results were reviewed. Statistical analysis determined odds of pre-sensitization in patients exposed to homograft tissue.

RESULTS

Fifty-six CHD patients underwent transplant during the review period. Thirteen patients (23%) were pre-sensitized by PRA>10%. By SAB testing, 33 patients (59%) developed any anti-HLA antibody >0 MFI, 30 patients (54%) >2000 MFI, and 19 patients (34%) >6000 MFI. Patients with homografts were more likely to be pre-sensitized by PRA (OR = 7.31, p = .007), and to have developed any anti-HLA antibody at various levels, >0 (OR = 4.52, p = .034), >2000 (OR = 8.59, p = .003), and >6000 (OR = 8.50, p = .004). Of patients with homografts, those pre-sensitized by PRA had longer exposure times (9.80 vs 4.96 years, p = .025). There was no difference in exposure time with relation to pre-sensitization by SAB testing.

CONCLUSIONS

Previous exposure to homograft tissue appears to increase the odds of pre-sensitization by either the PRA or SAB testing. Longer exposure time to homograft tissue prior to transplant is associated with increased pre-sensitization at transplant as determined by PRA, though not by SAB testing.