OPTN/SRTR 2019 Annual Data Report: Heart

Baicalein relieves lung graft ischemia-reperfusion injury by reducing advanced glycation endproducts: From screens to mechanisms

BACKGROUND

The lack of effective drugs for treating ischemia-reperfusion injury (IRI) in lung transplants (LTx) remains an issue. Traditional Chinese medicine (TCM) ingredients are promising but poorly studied in LTx. This study aimed to identify potential ingredients and elucidate their mechanisms.

METHODS

Ten TCM ingredients, including (-)-epigallocatechin-3-gallate, quercetin, wogonin, triptolide, berberine, fisetin, coumestrol, luteolin, nobiletin, and baicalein, were identified as promising candidates using a network pharmacology approach. All the candidates were tested for their ability to improve clamp-induced IRI. Multiple-dose validation was conducted in LTx models, with a focus on baicalein. The pharmacological efficacy of baicalin was verified in an ex-vivo rat lung perfusion model.

RESULTS

All ten TCM ingredients improved clamp-induced IRI. Multiple-dose validation confirmed that baicalein mitigated IRI-induced graft damage and dysfunction. Baicalein reduced the elevated levels of advanced glycation endproducts (AGEs) and their downstream pathogenic effects induced by IRI. Exogenous AGEs counteracted the therapeutic effect of baicalein. Baicalein inhibited AGE formation by modulating glucose oxidation rather than polyol metabolism.

CONCLUSIONS

This study provides a laboratory foundation for the use of TCM ingredients in the treatment of IRI in LTx.

Clinical Outcomes for Heart-Alone and Multiorgan Transplant Under the New Heart Allocation Policy Era

BACKGROUND

In October 2018, a new heart transplant allocation policy was implemented in the United States to address inequalities. Under the new policy, some patient outcomes for patients with heart transplant have improved; however, outcomes of multiorgan transplants combined with heart remain unclear.

METHODS

We examined the waitlist mortality, time to transplant, and posttransplant survival for all patients listed between 2013 and 2022 for multiorgan transplants with heart (n=3798) and compared the old policy era to the new policy era using cumulative incident curves and multivariable Cox regression models. Cumulative incidence curves also compared multiorgan transplants to patients listed for heart alone (n=31 840) under the new policy era.

RESULTS

Patients awaiting multiorgan transplants had higher use of intra-aortic balloon pumps (4.7% versus 11%) and extracorporeal membrane oxygenation support (2.4% versus 4.9%) in the new policy era. Under the new policy, despite receiving transplants sooner (n=2200 transplants, hazard ratio [HR], 1.74 [95% CI, 1.59-1.91]), patients who received multiorgan transplants had no change in waitlist mortality (n=340 deaths, HR, 1.06 [95% CI, 0.84-1.34]) compared with the old policy era. The rate of death post-multiorgan transplant was significantly higher in incidence curves under the new policy compared with the old policy era (log-rank P=0.02). However, in multivariable Cox models, the risk of death post-multiorgan transplant was similar under the new policy (n=287 deaths, HR, 1.11 [95% CI, 0.87-1.41]) compared with the old policy era.

CONCLUSIONS

Under the new policy, waitlist deaths have decreased for patients awaiting heart alone, but not for those awaiting multiorgan transplants. Post-transplant survival remains lower for patients who underwent multiorgan transplant (compared with heart-alone transplant), with no change under the new policy.

Development and validation of a clinical prediction model for dialysis-requiring acute kidney injury following heart transplantation: a single-center study from China

OBJECTIVES

This study seeks to construct and internally validate a clinical prediction model for predicting new-onset dialysis-requiring acute kidney injury (AKI) following heart transplantation (HT).

METHODS

The Kaplan-Meier survival analysis and log-rank test were utilized for conducting the survival analysis. A clinical prediction model was developed to predict postoperative dialysis-requiring AKI, based on a logistic regression model and likelihood ratio test with Akaike Information Criterion. The performance of the prediction model was assessed using C-index, receiver operating characteristic curves, calibration curves, Brier score, and the Spiegelhalter Z-test. Clinical utility was evaluated using decision curve analysis and clinical impact curves.

RESULTS

This study included a total of 525 patients who underwent orthotopic HT in the single center located in Wuhan, China between January 2015 and December 2021, with 16.57% developing postoperative dialysis-requiring AKI. Patients who experienced postoperative dialysis-requiring AKI exhibited a lower overall survival rate. All enrolled participants were randomly allocated into derivation (n = 350) and validation (n = 175) cohorts at a ratio of 2:1. The final prediction model comprised six indicators: diabetes, stroke, gout, prognostic nutritional index, estimated glomerular filtration rate, and cardiopulmonary bypass duration. The prediction model demonstrated outstanding discrimination (C-index of 0.792 in the derivation cohort and 0.834 in the validation cohort) as well as calibration performance, indicating strong concordance between observed and nomogram-predicted probabilities. Subgroup analysis based on age, preoperative serum creatine levels, and year of surgery also exhibited robust discrimination and calibration capabilities.

CONCLUSIONS

Dialysis-requiring AKI following HT is associated with poor clinical prognosis. The prediction model, comprising six indicators, is capable of predicting dialysis-requiring AKI following HT. This prediction model holds promise in assisting both patients and clinicians in forecasting postoperative renal failure, thereby improving clinical management.

CLINICAL TRIAL NUMBER

Not applicable.

Advancement of Heart Transplantation in Thai Recipients: Survival Trends and Pharmacogenetic Insights

Since 1987, King Chulalongkorn Memorial Hospital (KCMH) has performed a substantial number of heart transplants as a specific therapy for advanced-stage heart failure. This descriptive study aimed to analyze post-transplant survival in the recent era compared to earlier periods and examine the pharmacogenetics of related immunosuppressants. Data from all recipients who underwent heart transplants from 1987 to 2021 were retrospectively retrieved from the electronic medical record. The genotypes of relevant pharmacogenes were analyzed in recipients who were alive during the enrollment period. Kaplan-Meier analysis revealed improved overall survival rates in the recent era compared to the past. Dilated cardiomyopathy was identified as the most common pretransplant diagnosis, while infection remained the leading cause of mortality. In conclusion, the findings demonstrate significant advancements in the quality of heart transplantation in Thailand. Future studies are warranted to explore the correlation between pharmacogenetic variations identified in this study and subsequent clinical outcomes, with a focus on genetic-guided treatment to optimize patient care.

Heart transplantation in adults with congenital heart diseases: A comprehensive meta-analysis on waiting times, operative, and survival outcomes

The rising prevalence of congenital heart disease (CHD) among adults has led to increased heart transplantation (HT) procedures in this population. However, CHD patients face significant challenges including longer waiting times, higher early mortality rates, and increased risks of complications such as renal dysfunction. This systematic review and meta-analysis examined 50 studies to assess waiting times, postoperative outcomes, and survival rates in CHD patients undergoing HT compared to non-CHD patients. Results revealed that CHD patients experience longer HT waiting times (mean difference [MD]: 53.86 days, 95 % CI: [22.00, 85.72], P = 0.0009) and increased ischemic times (MD: 20.01 min, 95 % CI: [10.51, 29.51], P < 0.0001), which may increase waitlist and early postoperative mortality. Regarding complications, renal dysfunction is more prevalent in CHD patients than in non-CHD patients (RR: 2.05, 95 % CI: [1.61, 2.61], P < 0.00001). Despite these challenges, long-term survival rates for CHD patients are comparable to those of non-CHD recipients, with significant improvements noted in recent allocation systems. Our findings emphasize the need for ongoing refinements in HT allocation systems to improve outcomes for CHD patients, particularly in reducing waiting times and managing post-transplant complications.

Immune suppression sustained allograft acceptance requires PD1 inhibition of CD8+ T cells

Organ transplant recipients require continual immune-suppressive therapies to sustain allograft acceptance. Although medication nonadherence is a major cause of rejection, the mechanisms responsible for graft loss in this clinically relevant context among individuals with preceding graft acceptance remain uncertain. Here, we demonstrate that skin allograft acceptance in mice maintained with clinically relevant immune-suppressive therapies, tacrolimus and mycophenolate, sensitizes hypofunctional PD1hi graft-specific CD8+ T cells. Uninterrupted immune-suppressive therapy is required because drug discontinuation triggers allograft rejection, replicating the requirement for immune-suppressive therapy adherence in transplant recipients. Graft-specific CD8+ T cells in allograft-accepted mice show diminished effector differentiation and cytokine production, with reciprocally increased PD1 expression. Allograft acceptance-induced PD1 expression is essential, as PDL1 blockade reinvigorates graft-specific CD8+ T cell activation with ensuing allograft rejection despite continual immune-suppressive therapy. Thus, PD1 sustained CD8+ T cell inhibition is essential for allograft acceptance maintained by tacrolimus plus mycophenolate. This necessity for PD1 in sustaining allograft acceptance explains the high rates of rejection in transplant recipients with cancer administered immune checkpoint inhibitors targeting PD1/PDL1, highlighting shared immune suppression pathways exploited by tumor cells and current therapies for averting allograft rejection.

Identification of a Highly Functional Effector CD8 + T Cell Program after Transplantation in Mice and Humans

Acute T cell mediated rejection of allografts remains a significant risk factor for early graft loss. Our prior work defined a population of graft-specific CD8 + T cells positive for the activated receptor CD43 (expressing the 1B11 epitope) that form during acute rejection, leading us to further understand the in vivo fate and clinical relevance of this population. We found that during acute rejection, the CD43 + ICOS + phenotype was sensitive for proliferative graft-specific CD8 + T cells. We evaluated whether CD43 1B11 signaling could impact graft survival, and found that CD43 1B11 mAb treatment could overcome costimulation-blockade induced tolerance in the majority of mice. Using an adoptive transfer approach, we investigated the fate of CD43 1B11 + and CD43 1B11 - CD8 + T cell populations, and found that CD43 1B11 + CD8 + T cells were more persistent three weeks after transplantation. A portion of CD43 1B11 - CD8 + T cells converted to CD43 1B11 + , while CD43 1B11 + CD8 + T cells retained CD43 1B11 + status. In healthy human donors, we found that the CD43 1D4 clone, which identifies the large CD43 isoform, defines a population of antigen-experienced CD8 + T cells independent of the canonical CD8 + T cell populations. CD43 1D4 + CD8 + T cells were efficient cytokine-producers after stimulation. In scRNA-seq analysis of graft-infiltrating cells from renal transplant patients experiencing acute rejection, a population of SPN + GCNT1 + CD8 + T cells had an effector phenotype that includes high expression of IFNG, ICOS, and perforins/granzymes. Together, these data provide evidence that the CD43 1B11 expression defines a proliferative and persistent population of CD8 + T cells in mice, and that an analogous population of antigen-experienced CD8 + T cells that participate in allograft rejection.

Improving lung allograft function in the early post-operative period through the inhibition of pyroptosis

Lung transplantation is the only definitive therapy for end-stage pulmonary disease. Less than 20 % of offered lungs are successfully transplanted due to a limited ischemic time window and poor donor lung quality manifested by pulmonary edema, hypoxia, or trauma. Therefore, poor donor organ recovery and utilization are significant barriers to wider implementation of the life-saving therapy of transplantation. While ischemia reperfusion injury (IRI) is often identified as the underlying molecular insult leading to immediate poor lung function in the post-operative period, this injury encompasses several pathways of cellular injury in addition to the recruitment of the innate immune system to the site of injury to propagate this inflammatory cascade. Pyroptosis is a central molecular inflammatory pathway that is the most significant contributor to injury in this early post-operative phase. Pyroptosis is another form of programmed cell death and is often associated with IRI. The mitigation of pyroptosis in the early post-operative period following lung transplantation is a potential novel way to prevent poor allograft function and improve outcomes for all recipients. Here we detail the pyroptotic pathway, its importance in lung transplantation, and several therapeutic modalities that can mitigate this harmful inflammatory pathway.

Donor plasma VEGF-A as a biomarker for myocardial injury and primary graft dysfunction after heart transplantation

BACKGROUND

Vascular endothelial growth factor (VEGF)-A is an angiogenic and proinflammatory cytokine with profound effects on microvascular permeability and vasodilation. Several processes may induce VEGF-A expression in brain-dead organ donors. However, it remains unclear whether donor VEGF-A is linked to adverse outcomes after heart transplantation.

METHODS

We examined plasma VEGF-A levels from 83 heart transplant donors as well as the clinical data of these donors and their respective recipients operated between 2010 and 2016. The donor plasma was analyzed using Luminex-based Multiplex and confirmed with a single-target ELISA. Based on donor VEGF-A plasma levels, the recipients were divided into 3 equal-sized groups (low VEGF <500 ng/liter, n = 28; moderate VEGF 500-3000 ng/liter, n = 28; and high VEGF >3000 ng/liter, n = 27). Biochemical and clinical parameters of myocardial injury as well as heart transplant and kidney function were followed-up for one year, while rejection episodes, development of cardiac allograft vasculopathy, and mortality were monitored for 5 years.

RESULTS

Baseline parameters were comparable between the donor groups, except for age, where median ages of 40, 45, and 50 were observed for low, moderate, and high donor plasma VEGF levels groups, respectively, and therefore donor age was included as a confounding factor. High donor plasma VEGF-A levels were associated with pronounced myocardial injury (TnT and TnI), a higher inotrope score, and a higher incidence of primary graft dysfunction in the recipient after heart transplantation. Furthermore, recipients with allografts from donors with high plasma VEGF-A levels had a longer length of stay in the intensive care unit and the hospital, and an increased likelihood for prolonged renal replacement therapy.

CONCLUSIONS

Our findings suggest that elevated donor plasma VEGF-A levels were associated with adverse outcomes in heart transplant recipients, particularly in terms of myocardial injury, primary graft dysfunction, and long-term renal complications. Donor VEGF-A may serve as a potential biomarker for predicting these adverse outcomes and identifying extended donor criteria.

Approval of Mycophenolate Mofetil for Prophylaxis of Organ Rejection in Pediatric Recipients of Heart or Liver Transplants: A Regulatory Perspective

On June 6, 2022, the FDA expanded the indications for mycophenolate mofetil (MMF) to include the prophylaxis of organ rejection in combination with other immunosuppressants in pediatric recipients of allogeneic heart or liver transplants aged 3 months and older. The approved oral dosing regimen for these patients was a starting dose of 600 mg/m2 with titration up to a maximum of 900 mg/m2 twice daily. Data to support efficacy in pediatric patients were derived from established pharmacokinetic (PK) relationships across approved populations, a PK study in pediatric liver transplant recipients, and information from the Scientific Registry of Transplant Recipients database. Information supporting safety was based on comparing mycophenolic acid (MPA) exposure with that in pediatric kidney transplant recipients, the published literature, and post-marketing safety reports. Efficacy in pediatric patients was established based on extrapolation of efficacy from studies in adult liver, adult heart, and pediatric kidney transplant populations, and similarity in MPA exposure between pediatric and adult patients. Review of the data supported an oral dosing regimen for pediatric heart transplant and liver transplant recipients consisting of a starting dose of 600 mg/m2 up to a maximum of 900 mg/m2 b.i.d. A dosage range for MMF is recommended recognizing that the MMF dose may be modified in clinical practice for myriad factors. The dosage recommendations in the labeling for pediatric liver and pediatric heart transplant patients are intended to permit individualized dosing based on clinical assessment of these factors.

The Utility of the Vasoactive-Inotropic Score and Its Nomogram in Guiding Postoperative Management in Heart Transplant Recipients

Background

In the early postoperative stage after heart transplantation, there is a lack of predictive tools to guide postoperative management. Whether the vasoactive-inotropic score (VIS) can aid this prediction is not well illustrated.

Methods

In total, 325 adult patients who underwent heart transplantation at our center between January 2015 and December 2018 were included. The maximum VIS (VISmax) within 24 h postoperatively was calculated. The Kaplan-Meier method was used for survival analysis. A logistic regression model was established to determine independent risk factors and to develop a nomogram for a composite severe adverse outcome combining early mortality and morbidity.

Results

VISmax was significantly associated with extensive early outcomes such as early death, renal injury, cardiac reoperation and mechanical circulatory support in a grade-dependent manner, and also predicted 90-day and 1-year survival (p < 0.05). A VIS-based nomogram for the severe adverse outcome was developed that included VISmax, preoperative advanced heart failure treatment, hemoglobin and serum creatinine. The nomogram was well calibrated (Hosmer-Lemeshow p = 0.424) with moderate to strong discrimination (C-index = 0.745) and good clinical utility.

Conclusion

VISmax is a valuable prognostic index in heart transplantation. In the early post-transplant stage, this VIS-based nomogram can easily aid intensive care clinicians in inferring recipient status and guiding postoperative management.

MG53 mitigates warm ischemic lung injury in a murine model of transplantation

OBJECTIVES

Lung transplant warm ischemia-reperfusion injury (IRI) results in cellular injury, inflammation, and poor graft function. Mitsugumin 53 (MG53) is an endogenous protein with cell membrane repair properties and the ability to modulate the inflammasome. We hypothesize that the absence of circulating MG53 protein in the recipient increases IRI, and higher levels of circulating MG53 protein mitigate IRI associated with lung transplantation.

METHODS

To demonstrate protection, wild-type (wt) lung donor allografts were transplanted into a wt background, a MG53 knockout (mg53-/-), or a constitutively overexpressed MG53 (tissue plasminogen activator-MG53) recipient mouse after 1 hour of warm ischemic injury. Mice survived for 5 days after transplantation. Bronchioalveolar lavage, serum, and tissue were collected at sacrifice. Bronchioalveolar lavage, serum, and tissue markers of apoptosis and a biometric profile of lung health were analyzed.

RESULTS

mg53-/- mice had significantly greater levels of markers of overall cell lysis and endothelial cell injury. Overexpression of MG53 resulted in a signature similar to that of wt controls. At the time of explant, tissue plasminogen activator-MG53 recipient tissue expressed significantly greater levels of MG53, measured by immunohistochemistry, compared with mg53-/-, demonstrating uptake of endogenous overexpressed MG53 into donor tissue.

CONCLUSIONS

In a warm IRI model of lung transplantation, the absence of MG53 resulted in increased cell injury and inflammation. Endogenous overexpression of MG53 in the recipient results in protection in the wt donor. Together, these data suggest that MG53 is a potential therapeutic agent for use in lung transplantation to mitigate IRI.

Association of Heart Transplant Volume with Presence of Lung Transplant Programs and Heart Transplant's SRTR One-year Survival Rating

BACKGROUND

 Several factors affect heart transplant (HTx) and lung transplant (LTx) program outcomes. Variabilities in institutional and community characteristics have been shown to influence survival. At present, half of HTx centers in the United States do not possess a concomitant LTx program. This study sought to better understand the characteristics of HTx with and without LTx programs.

METHODS

 Nationwide transplant data were collected from the Scientific Registry of Transplant Recipients (SRTR) in August 2020. SRTR star rating ranges from tier 1 (lowest) to tier 5 (highest). HTx volumes and SRTR star ratings for survival were compared between the centers with heart-only (H0) programs and the centers with heart-lung (HL) programs.

RESULTS

 SRTR star ratings were available for 117 transplant centers with one or more HTx reported. The median number of HTx performed over 1 year was 16 (interquartile range [IQR]: 2-29). The number of HL centers (n = 67, 57.3%) were comparable to H0 centers (n = 50, 42.7%; p = 0.14). The HTx volume at the HL centers (28 [IQR: 17-41]) exceeded the HTx volume at the H0 centers (13 [IQR: 9-23]; p < 0.01), but were comparable to the LTx volume at the HL centers (31 [IQR: 16-46]; p = 0.25). The median HTx one-year survival rating was 3 (IQR: 2-4) at both the H0 and HL centers (p = 0.85). The HTx and LTx volumes were positively associated with the respective 1-year survivals (p < 0.01).

CONCLUSION

 While the presence of an LTx program is not directly associated with HTx survival, it has a positive association with the HTx volume. The HTx and LTx volumes are positively associated with the 1-year survival.

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.

Novel portable hypothermic machine perfusion preservation device enhances cardiac viability of donated human hearts

Introduction

Heart transplant remains the gold standard treatment for patients with advanced heart failure. However, the list of patients waiting for a heart transplant continues to increase. We have developed a portable hypothermic oxygenated machine perfusion device, the VP.S ENCORE®, to extend the allowable preservation time. The purpose of this study was to test the efficacy of the VP.S. ENCORE® using deceased donors derived hearts.

Methods

Hearts from brain-dead donors not utilized for transplant (n = 11) were offered for research from the Texas Organ Sharing Alliance (TOSA), South and Central Texas' Organ Procurement Organization (OPO) and were preserved in the VP.S ENCORE® for 4 (n = 2), 6 (n = 3), and 8 (n = 3) hours or were kept in static cold storage (SCS) (n = 3). After preservation, the hearts were placed in an isolated heart Langendorff model for reperfusion and evaluated for cardiac function.

Results

The mean donor age was 37.82 ± 12.67 with the youngest donor being 19 and the oldest donor being 58 years old. SCS hearts mean weight gain (%) was -1.4 ± 2.77, while perfused at 4 h was 5.6 ± 6.04, perfused at 6 h 2.1 ± 6.04, and 8 h was 7.2 ± 10.76. Venous and arterial lactate concentrations were less than 2.0 mmol/L across all perfused hearts. Left ventricular contractility (+dPdT, mmHg/s) for 4 h (1,214 ± 1,064), 6 (1,565 ± 141.3), and 8 h (1,331 ± 403.6) were within the range of healthy human heart function. Thus, not significant as compared to the SCS group (1,597 ± 342.2). However, the left ventricular relaxation (mmHg/s) was significant in 6-hour perfused heart (p < 0.05) as compared to SCS. Gene expression analysis of inflammation markers (IL-6, IL-1β) showed no significant differences between SCS and perfused hearts, but a 6-hour perfusion led to a downregulated expression of these markers.

Discussion

The results demonstrate that the VP.S ENCORE® device enhances cardiac viability and exhibits comparable cardiac function to a healthy heart. The implications of these findings suggest that the VP.S ENCORE® could introduce a new paradigm in the field of organ preservation, especially for marginal hearts.

Later Brain Death Declaration Correlates to Favorable Donor Characteristics but Decreased Heart Acceptance

BACKGROUND

With rates of potential donor heart discard as high as 66% nationally, quality improvement efforts must seek to optimize donor utilization. Whether the timing of donor brain death declaration (BDD) influences organ acceptance is understudied. The authors sought to characterize the impacts of time between donor hospital admission and BDD on heart utilization and posttransplant outcomes.

METHODS

All potential heart donors and recipients in the United Network for Organ Sharing database were identified (2006-2021). Admission-to-BDD cohorts were: 1 to 2 d (n = 52 469), 3 to 4 d (n = 44 033), 5 to 7 d (n = 24 509), and 8 to 10 d (n = 8576). Donor clinical characteristics were compared between cohorts, and donor acceptance was assessed using multivariable binary logistic regression. Recipient posttransplant survival was assessed with the Kaplan-Meier method.

RESULTS

Donor demographics and comorbidity profiles (diabetes and hypertension) were comparable across cohorts. Anoxia/overdose deaths were more common (10% > 21% > 24% > 18%, respectively) and cardiopulmonary resuscitation requirements were higher (37% > 52% > 58% > 47%) when BDD occurred longer after admission. Renal dysfunction (44% > 44% > 35% > 29%) and inotrope requirements (52% > 25% > 36% > 29%) were lower in the later BDD cohorts. Proportions of hepatic dysfunction (18%-21%) and left ventricular ejection fraction <50% (13%-16%) were clinically equivalent. Donor acceptance differed by admission-to-BDD cohort (36% [1-2 d], 34% [3-4 d], 30% [5-7 d], and 28% [8-10 d]). Admission-to-BDD >4 d was independently associated with lower odds of acceptance on multivariable analysis (odds ratio 0.79, P  < 0.001). Recipients experienced equivalent posttransplant survival for all donor admission-to-BDD cohorts ( P  = 0.999 adults and P  = 0.260 pediatrics).

CONCLUSIONS

Heart donors with later BDD were disproportionately discarded despite similar-to-favorable overall clinical profiles, resulting in nearly 3000 fewer transplants during the study. Increased utilization of donors with later BDD and "high-risk" characteristics (eg, anoxia/overdose, cardiopulmonary resuscitation requirement) can improve rates of transplantation without compromising outcomes.

Impact of the coronavirus disease 2019 pandemic on drug overdoses in the United States and the effect on cardiac transplant volume and survival

BACKGROUND

Drug overdose (DO) deaths rose to unprecedented levels during the coronavirus disease 2019 (COVID-19) pandemic. This study examines the impact of COVID-19 on the availability of cardiac allografts from DO donors and the implications of DO donor use on recipient survival.

METHODS

Heart transplants reported to the United Network for Organ Sharing from January 2017 to November 2019 ("pre-COVID") and from March 2020 to June 2021 ("COVID pandemic") were analyzed with respect to DO donor status. Outcomes were analyzed using Kaplan-Meier survival and Cox regression to identify predictors of survival. Characteristics of discarded cardiac allografts were also compared by DO donor status.

RESULTS

During the COVID-19 pandemic, 27.2% of cardiac allografts were from DO donors vs 20.5% pre-COVID, a 32.7% increase (p < 0.001). During the pandemic, DO donors were younger (84.7% vs 76.3% <40 years, p < 0.001), had higher cigarette use (16.1% vs 10.8%, p < 0.001), higher cocaine use (47.4% vs 19.7%, p < 0.001), and higher incidence of hepatitis C antibodies (26.8% vs 6.1%, p < 0.001) and RNA positivity (16.2% vs 4.2%, p < 0.001). While DO donors were less likely to require inotropic support (30.8% vs 35.4%, p = 0.008), they were more likely to have received cardiopulmonary resuscitation (95.3% vs 43.2%, p < 0.001). Recipient survival was equivalent using Kaplan-Meier analysis (log-rank, p = 0.33) and survival probability at 36 months was 85.6% (n at risk = 398) for DO donors vs 83.5% (n at risk = 1,633) for all other donors. Cox regression demonstrated that DO donor status did not predict mortality (hazard ratio 1.05; 95% confidence interval 0.90-1.23, p = 0.53).

CONCLUSIONS

During the COVID-19 pandemic, there was a 32.7% increase in heart transplants utilizing DO donor hearts, and DO became the most common mechanism of death for donors. The use of DO donor hearts did not have an impact on short-term recipient survival.

Donation after circulatory death significantly reduces waitlist times while not changing post-heart transplant outcomes: A United Network for Organ Sharing Analysis

BACKGROUND

Recently, several centers in the United States have begun performing donation after circulatory death (DCD) heart transplants (HTs) in adults. We sought to characterize the recent use of DCD HT, waitlist time, and outcomes compared to donation after brain death (DBD).

METHODS

Using the United Network for Organ Sharing database, 10,402 adult (aged >18 years) HT recipients from January 2019 to June 2022 were identified: 425 (4%) were DCD and 9,977 (96%) were DBD recipients. Posttransplant outcomes in matched and unmatched cohorts and waitlist times were compared between groups.

RESULTS

DCD and DBD recipients had similar age (57 years for both, p = 0.791). DCD recipients were more likely White (67% vs 60%, p = 0.002), on left ventricular assist device (LVAD; 40% vs 32%, p < 0.001), and listed as status 4 to 6 (60% vs 24%, p < 0.001); however, less likely to require inotropes (22% vs 40%, p < 0.001) and preoperative extracorporeal membrane oxygenation (0.9% vs 6%, p < 0.001). DCD donors were younger (29 vs 32 years, p < 0.001) and had less renal dysfunction (15% vs 39%, p < 0.001), diabetes (1.9% vs 3.8%, p = 0.050), or hypertension (9.9% vs 16%, p = 0.001). In matched and unmatched cohorts, early survival was similar (p = 0.22). Adjusted waitlist time was shorter in DCD group (21 vs 31 days, p < 0.001) compared to DBD cohort and 5-fold shorter (DCD: 22 days vs DBD: 115 days, p < 0.001) for candidates in status 4 to 6, which was 60% of DCD cohort.

CONCLUSIONS

The community is using DCD mostly for those recipients who are expected to have extended waitlist times (e.g., durable LVADs, status >4). DCD recipients had similar posttransplant early survival and shorter adjusted waitlist time compared to DBD group. Given this early success, efforts should be made to expand the donor pool using DCD, especially for traditionally disadvantaged recipients on the waitlist.

Mitsugumin 53 mitigation of ischemia-reperfusion injury in a mouse model

OBJECTIVE

Primary graft dysfunction is often attributed to ischemia-reperfusion injury, and prevention would be a therapeutic approach to mitigate injury. Mitsugumin 53, a myokine, is a component of the endogenous cell membrane repair machinery. Previously, exogenous administration of recombinant human (recombinant human mitsugumin 53) protein has been shown to mitigate acute lung injury. In this study, we aimed to quantify a therapeutic benefit of recombinant human mitsugumin 53 to mitigate a transplant-relevant model of ischemia-reperfusion injury.

METHODS

C57BL/6J mice were subjected to 1 hour of ischemia (via left lung hilar clamp), followed by 24 hours of reperfusion. mg53-/- mice were administered exogenous recombinant human mitsugumin 53 or saline before reperfusion. Tissue, bronchoalveolar lavage, and blood samples were collected at death and used to quantify the extent of lung injury via histology and biochemical assays.

RESULTS

Administration of recombinant human mitsugumin 53 showed a significant decrease in an established biometric profile of lung injury as measured by lactate dehydrogenase and endothelin-1 in the bronchoalveolar lavage and plasma. Biochemical markers of apoptosis and pyroptosis (interleukin-1β and tumor necrosis factor-α) were also significantly mitigated, overall demonstrating recombinant human mitsugumin 53's ability to decrease the inflammatory response of ischemia-reperfusion injury. Exogenous recombinant human mitsugumin 53 administration showed a trend toward decreasing overall cellular infiltrate and neutrophil response. Fluorescent colocalization imaging revealed recombinant human mitsugumin 53 was effectively delivered to the endothelium.

CONCLUSIONS

These data demonstrate that recombinant human mitsugumin 53 has the potential to prevent or reverse ischemia-reperfusion injury-mediated lung damage. Although additional studies are needed in wild-type mice to demonstrate efficacy, this work serves as proof-of-concept to indicate the potential therapeutic benefit of mitsugumin 53 administration to mitigate ischemia-reperfusion injury.

Advancements in Heart Transplantation: Donor-Derived Cell-Free DNA as Next-Generation Biomarker

Heart failure, particularly in its advanced stages, significantly impacts quality of life. Despite progress in Guideline-Directed Medical Therapy (GDMT) and invasive treatments, heart transplantation (HT) remains the primary option for severe cases. However, complications such as graft rejection present significant challenges that necessitate effective monitoring. Endomyocardial biopsy (EMB) is the gold standard for detecting rejection, but its invasive nature, associated risks, and healthcare costs have shifted interest in non-invasive techniques. Donor-derived cell-free DNA (dd-cfDNA) has gained attention as a promising non-invasive biomarker for monitoring graft rejection. Compared to EMB, dd-cfDNA detects graft rejection early and enables clinicians to adjust immunosuppression promptly. Despite its advantages, dd-cfDNA testing faces challenges, such as the need for specialized technology and potential inaccuracies due to other clinical conditions. Additionally, dd-cfDNA cannot yet differentiate between types of graft rejection, and its effectiveness in chronic rejection remains unclear. Research is ongoing to set precise standards for dd-cfDNA levels, which would enhance its diagnostic accuracy and help in clinical decisions. The article also points to the future of HT monitoring, which may involve combining dd-cfDNA with other biomarkers and integrating artificial intelligence to improve diagnostic capabilities and personalize patient care. Furthermore, it emphasizes both global and racial inequalities in dd-cfDNA testing and the ethical issues related to its use in transplant medicine.

Cardiac Amyloidosis: Clinical Features, Pathogenesis, Diagnosis, and Treatment

Cardiac amyloidosis is a type of amyloidosis that deserves special attention as organ involvement significantly worsens the prognosis. Cardiac amyloidosis can be grouped under three main headings: immunoglobulin light chain (AL) amyloidosis that is dependent on amyloidogenic monoclonal light chain production; hereditary Transthyretin (TTR) amyloidosis that results from accumulation of mutated TTR; and wild-type (non-hereditary) TTR amyloidosis formerly known as senile amyloidosis. Although all three types cause morbidity and mortality due to severe heart failure when untreated, they contain differences in their pathogenesis, clinical findings, and treatment. In this article, the clinical features, pathogenesis, diagnosis, and treatment methods of cardiac amyloidosis will be explained with an overview, and an awareness will be raised in the diagnosis of this disease.

Flexible Conductive Decellularized Fish Skin Matrix as a Functional Scaffold for Myocardial Infarction Repair

Engineering cardiac patches are proven to be effective in myocardial infarction (MI) repair, but it is still a tricky problem in tissue engineering to construct a scaffold with good biocompatibility, suitable mechanical properties, and solid structure. Herein, decellularized fish skin matrix is utilized with good biocompatibility to prepare a flexible conductive cardiac patch through polymerization of polydopamine (PDA) and polypyrrole (PPy). Compared with single modification, the double modification strategy facilitated the efficiency of pyrrole polymerization, so that the patch conductivity is improved. According to the results of experiments in vivo and in vitro, the scaffold can promote the maturation and functionalization of cardiomyocytes (CMs). It can also reduce the inflammatory response, increase local microcirculation, and reconstruct the conductive microenvironment in infarcted myocardia, thus improving the cardiac function of MI rats. In addition, the excellent flexibility of the scaffold, which enables it to be implanted in vivo through "folding-delivering-re-stretehing" pathway, provides the possibility of microoperation under endoscope, which avoids the secondary damage to myocardium by traditional thoracotomy for implantation surgery.

Getting out of the box: the future of the UK donation after circulatory determination of death heart programme

Heart failure imposes a significant burden on all health care systems and has a 5-year mortality of 50%. Heart transplantation and ventricular assist device (VAD) implantation are the definitive therapies for end stage heart disease, although transplantation appears to offer superior long-term survival and quality of life over VAD implantation. Transplantation is limited by a shortage in donor hearts, resulting in considerable waiting list mortality. Donation after circulatory determination of death (DCD) offers a significant uplift in the number of donors for heart transplantation. The outcomes both from the UK and internationally have been exciting, with outcomes at least as good as conventional donation after brain death (DBD) transplantation. Currently, DCD hearts are reperfused using ex-situ machine perfusion (ESMP). Whilst ESMP has enabled the development of DCD transplantation, it comes at significant cost, with the per run cost of approximately GBP £90,000. In-situ perfusion of the heart, otherwise known as thoraco-abdominal normothermic regional perfusion (taNRP) is cheaper, but there are ethical concerns regarding the potential to restore cerebral perfusion in the donor. We must determine whether there is any cerebral circulation during in-situ perfusion of the heart to ensure that it does not invalidate the diagnosis of death and potentially violate the dead donor rule. Besides this, there is a need for a randomised controlled trial to definitively determine whether taNRP offers any clinical advantages over ex-situ machine perfusion. This viewpoint article explores these issues in more detail.

Impact of donor-recipient age-difference in adolescent heart transplantation

INTRODUCTION

The relationship between donor age and adolescent heart transplant outcomes remains incompletely understood. We aimed to explore the effect of donor-recipient age difference on survival after adolescent heart transplantation.

METHODS

The United Network for Organ Sharing database was used to identify 2,855 adolescents aged 10-17 years undergoing isolated primary heart transplantation from 1/1/2000 to 12/31/2022. The primary outcome was 10-year post-transplant survival. Multivariable Cox regression identified predictors of mortality after adjusting for donor and recipient characteristics. A restricted cubic spline assessed the non-linear association between donor-recipient age-difference and the adjusted relative mortality hazard.

RESULTS

The median donor-recipient age-difference was +3 (range -13 to +47) years, and 17.7% (n = 504) of recipients had an age- difference > 10 years. Recipients with an age-difference > 10 years had a less favorable pre-transplant profile, including a higher incidence of priority status 1A (81.6%, n = 411 vs. 73.6%, n = 1730; p = .01). The 10-year survival rate was 54.6% (95% confidence interval (CI) 48.8- 60.4) among recipients with a donor-recipient age-difference > 10 years and 66.9% (95% CI: 64.4-69.4) among those with an age-difference ≤10 years. An age-difference > 10 years was an independent predictor of mortality (hazard ratio 1.43, 95% CI: 1.18-1.72, p < .001). Spline analysis demonstrated that the adjusted mortality hazard increased with increasingly positive donor-recipient age-difference and became significantly higher at an age-difference of 11 years.

CONCLUSION

A donor-recipient age-difference > 11 years is independently associated with higher long-term mortality after adolescent heart transplantation. This finding may help inform acceptable donor selection practice for adolescent heart transplant candidates.

Heart Transplant and Donors After Circulatory Death: A Clinical-Preclinical Systematic Review

INTRODUCTION

Heart transplantation is the treatment of choice for end-stage heart failure. There is a mismatch between the number of donor hearts available and the number of patients awaiting transplantation. Expanding the donor pool is critically important. The use of hearts donated following circulatory death is one approach to increasing the number of available donor hearts.

MATERIALS AND METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines utilizing Pubmed/MEDLINE and Embase. Articles including adult human studies and preclinical animal studies of heart transplantation following donation after circulatory death were included. Studies of pediatric populations or including organs other than heart were excluded.

RESULTS

Clinical experience and preclinical studies are reviewed. Clinical experience with direct procurement, normothermic regional perfusion, and machine perfusion are included. Preclinical studies addressing organ function assessment and enhancement of performance of marginal organs through preischemic, procurement, preservation, and reperfusion maneuvers are included. Articles addressing the ethical considerations of thoracic transplantation following circulatory death are also reviewed.

CONCLUSIONS

Heart transplantation utilizing organs procured following circulatory death is a promising method to increase the donor pool and offer life-saving transplantation to patients on the waitlist living with end-stage heart failure. There is robust ongoing preclinical and clinical research to optimize this technique and improve organ yield. There are also ongoing ethical considerations that must be addressed by consensus before wide adoption of this approach.

Expanding use of the HeartMate 3 ventricular assist device in pediatric and adult patients within the Advanced Cardiac Therapies Improving Outcomes Network (ACTION)

BACKGROUND

We report current outcomes in patients supported with the HeartMate 3 (HM3) ventricular assist device in a multicenter learning network.

METHODS

The Advanced Cardiac Therapies Improving Outcomes Network database was queried for HM3 implants between 12/2017 and 5/2022. Clinical characteristics, postimplant course, and adverse events were collected. Patients were stratified according to body surface area (BSA) (<1.4 m2, 1.4-1.8 m2, and >1.8 m2) at device implantation.

RESULTS

During the study period, 170 patients were implanted with the HM3 at participating network centers, with median age 15.3years; 27.1% were female. Median BSA was 1.68 m2; the smallest patient was 0.73 m2 (17.7 kg). Most (71.8%) had a diagnosis of dilated cardiomyopathy. With a median support time of 102.5days, 61.2% underwent transplantation, 22.9% remained supported on device, 7.6% died, and 2.4% underwent device explantation for recovery; the remainder had transferred to another institution or transitioned to a different device type. The most common adverse events included major bleeding (20.8%) and driveline infection (12.9%); ischemic and hemorrhagic stroke were encountered in 6.5% and 1.2% of patients, respectively. Patients with BSA <1.4 m2 had a higher incidence of infection, renal dysfunction, and ischemic stroke.

CONCLUSIONS

In this updated cohort of predominantly pediatric patients supported with the HM3 ventricular assist device, outcomes are excellent with <8% mortality on device. Device-related adverse events including stroke, infection, and renal dysfunction were more commonly seen in smaller patients, highlighting opportunities for improvements in care.

Hepatitis C and heart transplantation: An update

There are limited data regarding heart transplantation in the setting of hepatitis C virus (HCV) infection in either recipients or donors, as the practice was infrequent, given concerns of worse post-transplant outcomes. This changed dramatically after the development of highly effective HCV therapies, namely direct-acting antivirals (DAAs). Additionally, nucleic acid testing currently in use establishes more precisely the risk of HCV transmission from donors. As a result, chronic HCV infection in itself is no longer a barrier for heart transplant candidates, and the use of HCV-positive organs for HCV-infected and non-infected transplant candidates has increased dramatically. A review of the literature revealed that in the pre-DAA era, HCV seropositive heart transplant patients had a higher mortality than their seronegative counterparts. However, short-term data suggest that the differences in survival have been erased in the DAA era. Heart transplantation from HCV-viremic donors to HCV-uninfected recipients has become increasingly common as the number of deceased donors with HCV viremia has increased over the past years. Preliminary outcome reports are very encouraging, although further data are needed with regard to long-term safety. New information continues to be incorporated to optimize protocols that guide this practice.

A novel intrapericardial pulsatile device for individualized, biventricular circulatory support without direct blood contact

OBJECTIVE

Due to severely limited donor heart availability, durable mechanical circulatory support remains the only treatment option for many patients with end-stage heart failure. However, treatment complexity persists due to its univentricular support modality and continuous contact with blood. We investigated the function and safety of reBEAT (AdjuCor GmbH), a novel, minimal invasive mechanical circulatory support device that completely avoids blood contact and provides pulsatile, biventricular support.

METHODS

For each animal tested, an accurately sized cardiac implant was manufactured from computed tomography scan analyses. The implant consists of a cardiac sleeve with three inflatable cushions, 6 epicardial electrodes and driveline connecting to an electro-pneumatic, extracorporeal portable driver. Continuous epicardial electrocardiogram signal analysis allows for systolic and diastolic synchronization of biventricular mechanical support. In 7 pigs (weight, 50-80 kg), data were analyzed acutely (under beta-blockade, n = 5) and in a 30-day long-term survival model (n = 2). Acquisition of intracardiac pressures and aortic and pulmonary flow data were used to determine left ventricle and right ventricle stroke work and stroke volume, respectively.

RESULTS

Each implant was successfully positioned around the ventricles. Automatic algorithm electrocardiogram signal annotations resulted in precise, real-time mechanical support synchronization with each cardiac cycle. Consequently, progressive improvements in cardiac hemodynamic parameters in acute animals were achieved. Long-term survival demonstrated safe device integration, and clear and stable electrocardiogram signal detection over time.

CONCLUSIONS

The present study demonstrates biventricular cardiac support with reBEAT. Various demonstrated features are essential for realistic translation into the clinical setting, including safe implantation, anatomical fit, safe device-tissue integration, and real-time electrocardiogram synchronized mechanical support, result in effective device function and long-term safety.

Temporal trends and outcomes of heart transplantation in Spain (2002-2021): propensity score matching analysis to compare patients with and without type 2 diabetes

BACKGROUND

The impact of Type 2 Diabetes (T2D) on the outcomes of heart transplantation (HT) has not yet been clearly established. The objectives of this study were to examine the trends in the prevalence of T2D among individuals who underwent a HT in Spain from 2002 to 2021, and to compare the clinical characteristics and hospitalization outcomes between HT recipients with and without T2D.

METHODS

We used the national hospital discharge database to select HT recipients aged 35 and older. The International Classification of Diseases, Ninth and Tenth Revisions (ICD-9 and ICD-10) were used to identify patients with and without T2D. We also recorded comorbidities, complications of HT, and procedures. Propensity score matching (PSM) and Cox regression were used to analyze the effect of T2D on in-hospital mortality (IHM).

RESULTS

Between 2002 and 2021, a total of 4429 HTs (T2D, 19.14%) were performed in Spain. The number of HTs in patients with T2D decreased from 2002 to 2005 (n = 171) to 2014-2017 (n = 154), then rose during 2018-2021 (n = 186). Complications of HT increased in patients with and without T2D over the study period (26.9% and 31.31% in 2002-2005 vs. 42.47% and 45.01% in 2018-2021, respectively). The results of the PSM showed that pneumonia and Gram-negative bacterial infections were less frequent in patients with T2D and that these patients less frequently required hemodialysis, extracorporeal membrane oxygenation (ECMO), and tracheostomy. They also had a shorter hospital stay and lower IHM than patients without diabetes. The variables associated with IHM in patients with T2D were hemodialysis and ECMO. IHM decreased over time in people with and without T2D. The Cox regression analysis showed that T2D was associated with lower IHM (HR 0.77; 95% CI 0.63-0.98).

CONCLUSIONS

The number of HTs increased in the period 2018-2021 compared with 2002-2005 in patients with and without T2D. Over time, complications of HT increased in both groups studied, whereas IHM decreased. The presence of T2D is associated with lower IHM.

High-dimensional profiling of pediatric immune responses to solid organ transplantation

Solid organ transplant remains a life-saving therapy for children with end-stage heart, lung, liver, or kidney disease; however, ∼33% of allograft recipients experience acute rejection within the first year after transplant. Our ability to detect early rejection is hampered by an incomplete understanding of the immune changes associated with allograft health, particularly in the pediatric population. We performed detailed, multilineage, single-cell analysis of the peripheral blood immune composition in pediatric solid organ transplant recipients, with high-dimensional mass cytometry. Supervised and unsupervised analysis methods to study cell-type proportions indicate that the allograft type strongly influences the post-transplant immune profile. Further, when organ-specific differences are considered, graft health is associated with changes in the proportion of distinct T cell subpopulations. Together, these data form the basis for mechanistic studies into the pathobiology of rejection and allow for the development of new immunosuppressive agents with greater specificity.

Sex differences in clinical characteristics and outcomes in patients undergoing heart transplantation

AIMS

Whether sex affects selection for and outcomes after heart transplantation (HTx) remains unclear. We aimed to show sex differences in pre-transplant characteristics and outcomes after HTx.

METHODS AND RESULTS

From 1995 to 2019, 49 200 HTx recipients were prospectively enrolled in the Organ Procurement and Transplantation Network. Logistic regression models were used to evaluate clinical characteristics by sex. Multivariable Cox regression models were fitted to assess sex differences in all-cause mortality, cardiovascular mortality, graft failure, cardiac allograft vasculopathy (CAV), and malignancy. In 49 200 patients (median age 55 years, interquartile range 46-62; 24.6% women), 49 732 events occurred during a median follow-up of 8.1 years. Men were older than women, had more often ischaemic cardiomyopathy (odds ratio [OR] 3.26, 95% confidence interval [CI] 3.11-3.42; P < 0.001), and a higher burden of cardiovascular risk factors, whereas women had less malignancies (OR 0.47, CI 0.44-0.51; P < 0.001). Men were more often treated in intensive care unit (OR 1.24, CI 1.12-1.37; P < 0.001) with a higher need for ventilatory (OR 1.24, CI 1.17-1.32; P < 0.001) or VAD (OR 1.53, CI 1.45-1.63; P < 0.001) support. After multivariable adjustment, men had a higher risk for CAV (hazard ratio [HR] 1.21, CI 1.13-1.29; P < 0.001) and malignancy (HR 1.80, CI 1.62-2.00; P < 0.001). There were no differences in all-cause mortality, cardiovascular mortality, and graft failure between sexes.

CONCLUSIONS

In this US transplant registry, men and women differed in pre-transplant characteristics. Male sex was independently associated with incident CAV and malignancy even after multivariable adjustment. Our results underline the need for better personalized post-HTx management and care.

Impact of 2018 allocation system change on outcomes in patients with durable left ventricular assist device as bridge to transplantation: A UNOS registry analysis

BACKGROUND

This study compared outcomes of patients waitlisted for orthotopic heart transplantation with durable left ventricular assist devices (LVAD) before and after the October 18, 2018 heart allocation policy change.

METHODS

The United Network of Organ Sharing database was queried to identify 2 cohorts of adult candidates with durable LVAD listed within seasonally-matched, equal-length periods before (old policy era [OPE]) and after the policy change (new policy era [NPE]). The primary outcomes were 2-year survival from the time of initial waitlisting, as well as 2-year post-transplant survival. Secondary outcomes included incidence of transplantation from the waitlist and de-listing due to either death or clinical deterioration.

RESULTS

A total of 2,512 candidates were waitlisted, 1,253 within the OPE and 1,259 within the NPE. Candidates under both policies had similar 2-year survival after waitlisting, as well as a similar cumulative incidence of transplantation and de-listing due to death and/or clinical deterioration. A total of 2,560 patients were transplanted within the study period, 1,418 OPE and 1,142 within the NPE. Two-year post-transplant survival was similar between policy eras, however, the NPE was associated with a higher incidence of post-transplant stroke, renal failure requiring dialysis, and a longer hospital length of stay.

CONCLUSIONS

The 2018 heart allocation policy has conferred no significant impact on overall survival from the time of initial waitlisting among durable LVAD-supported candidates. Similarly, the cumulative incidence of transplantation and waitlist mortality have also been largely unchanged. For those undergoing transplantation, a higher degree of post-transplant morbidity was observed, though survival was not impacted.

Optimal Donor Allograft Function: The Search for the Lowest Acceptable Donor Left Ventricular Ejection Fraction in Pediatric Heart Transplantation

BACKGROUND

The availability of heart donors is limited by organ shortage. Due to concerns of reduced survival, donors with depressed left ventricular ejection fraction (LVEF <50%) have been cautiously used in pediatric heart transplantation. One strategy to expand the donor pool is to re-evaluate whether lower donor LVEF may be acceptable for transplantation.

METHODS

We performed a multicenter retrospective cohort study of patients <18 y receiving heart transplants from April 2007 to September 2021 using the United Network of Organ Sharing dataset. We excluded retransplants and multiorgan transplants. Cut-point analyses of LVEF was performed and Kaplan-Meier method was used to compare 1-y survival for new cut-points and the standard (LVEF >50%).

RESULTS

The analytic sample consisted of 5255 patients. Recipients receiving hearts with lower LVEFs were more likely to be on ventilator and extracorporeal membrane oxygenation support. Recipients did not differ in waitlist times or transplant status. Cut-point analysis identified LVEF 45% as a potentially new cutoff. One-year survival of recipients of donors with LVEF ≥45% (92.1%; 95% confidence interval [CI], 91.3%-92.8%) was similar to that of LVEF >50% (92.1%; CI, 91.4%-92.9%). Survival for the LVEF 45%-49% (88.8%; CI, 72.9%-95.7%) cohort was slightly lower than the ≥50% cohort, albeit nonsignificant.

CONCLUSIONS

One-year survival among pediatric heart transplants using a donor heart LVEF threshold of 45% or 40% was similar to a threshold of 50%. However, the finding is based on a small number of patients with LVEF <50%, and future larger prospective studies are warranted to confirm the findings of this study before a lower LVEF threshold is considered.

Morbidity and Mortality in Adult Fontan Patients After Heart or Combined Heart-Liver Transplantation

BACKGROUND

An increasing number of adult Fontan patients require heart transplantation (HT) or combined heart-liver transplant (CHLT); however, data regarding outcomes and optimal referral time remain limited.

OBJECTIVES

The purpose of this study was to define survivorship post-HT/CHLT and predictors of post-transplant mortality, including timing of referral, in the adult Fontan population.

METHODS

A retrospective cohort study of adult Fontan patients who underwent HT or CHLT across 15 centers in the United States and Canada was performed. Inclusion criteria included the following: 1) Fontan; 2) HT/CHLT referral; and 3) age ≥16 years at the time of referral. Date of "failing" Fontan was defined as the earliest of the following: worsening fluid retention, new ascites, refractory arrhythmia, "failing Fontan" diagnosis by treating cardiologist, or admission for heart failure.

RESULTS

A total of 131 patients underwent transplant, including 40 CHLT, from 1995 to 2021 with a median post-transplant follow-up time of 1.6 years (Q1 0.35 years, Q3 4.3 years). Survival was 79% at 1 year and 66% at 5 years. Survival differed by decade of transplantation and was 87% at 1 year and 76% at 5 years after 2010. Time from Fontan failure to evaluation (HR/year: 1.23 [95% CI: 1.11-1.36]; P < 0.001) and markers of failure, including NYHA functional class IV (HR: 2.29 [95% CI: 1.10-5.28]; P = 0.050), lower extremity varicosities (HR: 3.92 [95% CI: 1.68-9.14]; P = 0.002), and venovenous collaterals (HR: 2.70 [95% CI: 1.17-6.20]; P = 0.019), were associated with decreased post-transplant survival at 1 year in a bivariate model that included transplant decade.

CONCLUSIONS

In our multicenter cohort, post-transplant survival improved over time. Late referral after Fontan failure and markers of failing Fontan physiology, including worse functional status, lower extremity varicosities, and venovenous collaterals, were associated with post-transplant mortality.

Heart transplantation using donation after circulatory death in the United States

OBJECTIVES

Heart donation after circulatory death was recently reintroduced in the United States with hopes of increasing donor heart availability. We examined its national use and outcomes.

METHODS

The United Network for Organ Sharing database was used to identify validated adult patients undergoing heart transplantation using donation after circulatory death donors (n = 266) and donation after brain death donors (n = 5998) between December 1, 2019, and December 31, 2021, after excluding heart-lung transplants. Propensity score matching was used to create more balanced groups for comparison.

RESULTS

The monthly percentage of donation after circulatory death heart transplant increased from 2.5% in December 2019 to 6.8% in December 2021 (P < .001). Twenty-two centers performed donation after circulatory death heart transplants, ranging from 1 to 75 transplants per center. Four centers performed 70% of the national volume. Recipients of donation after circulatory death hearts were more likely to be clinically stable (80.4% vs 41.1% in status 3-6, P < .001), to have type O blood (58.3% vs 39.9%, P < .001), and to wait longer after listing (55, interquartile range, 15-180 days vs 32, interquartile range, 9-160 days, P = .003). Six-month survival was 92.1% (95% confidence interval, 91.3-92.8) after donation after brain death heart transplants and 92.6% (95% confidence interval, 88.1-95.4) after donation after circulatory death heart transplants (hazard ratio, 0.94, 95% confidence interval, 0.57-1.54, P = .79). Outcomes in propensity-matched patients were similar except for higher rates of treated acute rejection in donation after circulatory death transplants before discharge (14.4% vs 8.8%, P = .01). In donation after circulatory death heart recipients, outcomes did not differ based on the procurement technique (normothermic regional perfusion vs direct procurement and perfusion).

CONCLUSIONS

Heart transplantation with donation after circulatory death donors has short-term survival comparable to donation after brain death transplants. Broader implementation could substantially increase donor organ availability.

Do patient decision aids help people who are facing decisions about solid organ transplantation? A systematic review

BACKGROUND

Decisions about solid organ transplantation are complex. Patient decision aids (PDAs) enhance traditional education, by improving knowledge and supporting patients to align their values with treatments. There are increasing numbers of transplantation PDAs, however, it is unclear whether these are effective. We conducted a systematic review of studies assessing the impact of PDA use in transplantation.

METHODS

We searched the Cochrane Register of Controlled Trials, CINAHL, EMBASE, MEDLINE, and PsycINFO databases from database inception to October 26, 2020. We included primary studies of solid organ transplantation PDAs defined by the International Patient Decision Aids Standards. All comparators and reported outcomes were included. Mean difference in knowledge (before vs. after) was standardized on a 100-point scale. Pooled-effect for PDAs was calculated and compared to the standard of care for randomized controlled trials (RCTs) and meta-analyzed using random effects. Analysis of all other outcomes was limited due to heterogeneity (PROSPERO registration, CRD42020215940).

RESULTS

Seven thousand four hundred and sixty-three studies were screened, 163 underwent full-text review, and 15 studies with 4278 participants were included. Nine studies were RCTs. Seven RCTs assessed knowledge; all demonstrated increased knowledge with PDA use (mean difference, 8.01;95%CI 4.69-11.34, p < .00001). There were many other outcomes, including behavior and acceptability, but these were too heterogenous and infrequently assessed for meaningful synthesis.

CONCLUSIONS

This review found that PDAs increase knowledge compared to standard education, though the effect size is small. PDAs are mostly considered acceptable; however, it is difficult to determine whether they improve other decision-making components due to the limited evidence about non-knowledge-based outcomes.

Improvement in Racial Disparities in Heart Transplantation following the Heart Allocation Policy Change

Objectives. Heart transplantation (HT) is a definitive therapy for refractory heart failure, making it the gold-standard treatment for recipients with end-stage disease. Heart allocation policy (HAP) in the United States was changed on October 18th, 2018. The aim of this study was to assess the effect of the new policy on racial disparities in heart transplantation (HT) outcomes. Methods. The United Network for Organ Sharing (UNOS) registry was used to identify adult recipients undergoing isolated HT between 2010 and 2021. Recipients were stratified into pre-HAP (January 2010 to September 2018) vs. post-HAP (October 2018 to September 2021). Recipient race was classified as White, Black, Hispanic, or other. The primary outcome was post-HT mortality. Cox proportional hazard models were used for risk-adjustment in evaluating the independent effect of race on post-HT mortality. Results. A total of 27,403 recipients underwent HT in 143 centers during study period. The proportion of non-Whites undergoing HT increased in the post-HAP era: (pre-HAP: White 66.0%, Black 21.2%, Hispanic 8.2%, Other 4.6% versus post-HAP: White 62.5%, Black 23.2%, Hispanic 9.5%, Other 4.8%; $p<0.001$ ). In risk-adjusted analysis, Black recipients were at higher risk of post-HT mortality in the pre-HAP era (HR 1.31, 95% CI 1.22–1.41; $p<0.001$ ) but not in the post-HAP era (HR 1.12, 95% CI 0.03–1.34; $p=0.222$ ) compared to White recipients. Other non-White recipients had comparable risk-adjusted post-HT mortality rates compared to White recipients both in the pre-HAP and post-HAP eras. Conclusions. Under the new heart allocation system, a higher percentage of recipients are non-White. In addition, racial disparities in HT outcomes have improved with Black recipients no longer having an increased risk-adjusted mortality following HT.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Donation after circulatory determination of death in heart transplant: impact on current and future allocation policy

PURPOSE OF REVIEW

Historically, the selection criteria for heart transplant candidates has prioritized posttransplant survival while contemporary allocation policy is focused on improving waitlist survival. Donor scarcity has continued to be the major influence on transplant allocation policy. This review will address the opportunity of donation after circulatory determination of death (DCDD) and potential impact on future policy revisions.

RECENT FINDINGS

In 2018, changes to U.S. heart allocation policy led to several intended and unintended consequences. Beneficial changes include reduced waitlist mortality and broader geographic sharing. Additional impacts include scarcer pathways to transplant for patients with a durable left ventricular assist device, increased reliance on status exceptions, and expanded use of temporary mechanical support. DCDD is anticipated to increase national heart transplant volumes by ∼30% and will impact waitlist management. Centers that offer DCDD procurement will have reduced waitlist times, reduced waitlist mortality, and higher transplant volumes.

SUMMARY

While DCDD will provide more transplant opportunities, donor organ scarcity will persist and influence allocation policies. Differential patient selection, waitlist strategy, and outcome expectations may indicate that allocation is adjusted based on the procurement options at individual centers. Future policy, which will consider posttransplant outcomes, may reflect that different procurement strategies may yield different outcomes.

Infection, Rejection, and the Connection

Solid organ transplantation is a life-saving treatment for people with end-stage organ disease. Immune-mediated transplant rejection is a common complication that decreases allograft survival. Although immunosuppression is required to prevent rejection, it also increases the risk of infection. Some infections, such as cytomegalovirus and BK virus, can promote inflammatory gene expression that can further tip the balance toward rejection. BK virus and other infections can induce damage that resembles the clinical pathology of rejection, and this complicates accurate diagnosis. Moreover, T cells specific for viral infection can lead to rejection through heterologous immunity to donor antigen directly mediated by antiviral cells. Thus, viral infections and allograft rejection interact in multiple ways that are important to maintain immunologic homeostasis in solid organ transplant recipients. Better insight into this dynamic interplay will help promote long-term transplant survival.

Heart transplant offers are less likely to be accepted on weekends, holidays, and conferences

BACKGROUND

The existence of a "weekend effect" in heart transplantation (HTx) is understudied. The present study sought to determine whether the odds of (HTx) offer acceptance differed for adult and pediatric candidates depending upon the day on which the offer occurred.

METHODS

United Network for Organ Sharing data were used to identify all HTx offers to adult (listing age ≥18) and pediatric candidates from 2000-2019. Odds of offer acceptance were studied, comparing weekends, holidays, and conferences (Society of Thoracic Surgeons [STS], American Association for Thoracic Surgery [AATS], International Society for Heart and Lung Transplantation [ISHLT]) to "baseline" (all other days). Multivariable binary logistic regression analyses were performed to determine independent predictors of offer nonacceptance, controlling for the impacts of program transplant volume, region, and candidate characteristics.

RESULTS

A total of 323,953 offers occurred - 298,405 to adults and 25,548 to pediatric candidates. Clinically significant differences did not exist in donor or candidate characteristics between baseline or other events. The number of offers per day was stable throughout the year for both adults (p = 0.191) and pediatrics (p = 0.976). In adults, independently lower odds of acceptance existed on weekends (OR 0.88 [95% CI 0.84-0.92]), conferences in aggregate (0.86 [0.77-0.95]), and holidays in aggregate (0.81 [0.72-0.91]). In children, independently lower odds of acceptance were seen on weekends (0.88 [0.79-0.98]), during STS (0.46 [0.25-0.83], and during Christmas (0.32 [0.14-0.76]).

CONCLUSIONS

The day on which a HTx offer occurs significantly impacts its likelihood of acceptance. Further work can determine the impacts of human behavior or resource distribution, but knowledge of this phenomenon can inform efforts to ensure ideal organ allocation throughout the year.

Counselling, Research Gaps, and Ethical Considerations Surrounding Pregnancy in Solid Organ Transplant Recipients

Survival after solid-organ transplantation has improved significantly, and many contemporary transplant recipients are of childbearing potential. There are limited data to guide decision-making surrounding pregnancy after transplantation, variations in clinical practice, and significant knowledge gaps, all of which raise significant ethical issues. Post-transplant pregnancy is associated with an increased risk of maternal and fetal complications. Shared decision-making is a central aspect of patient counselling but is complicated by significant knowledge gaps. Stakeholder interests can be in conflict; exploring these tensions can help patients to evaluate their options and inform their deliberations. We argue that uniform, evidence-based recommendations for pregnancy after solid organ transplantation are needed. Conducting research, including patient-engaged studies, in this area should be priority for the transplant community.

Outcomes of pediatric patients supported with ventricular assist devices single center experience

BACKGROUND

There has been a remarkable increase in the number of pediatric ventricular assist device (VAD) implanted over the past decade. Asian pediatric heart centers had not participated in the multicenter registries among the Western countries. This article aimed to report the outcomes of pediatric VAD in our hospital.

METHODS

The study enrolled all patients aged <18 years at the time of VAD implantation in our institution between 2008 and 2021.

RESULTS

There were 33 patients with diagnosis of acute fulminant myocarditis (n = 9), congenital heart disease (n = 5), dilated cardiomyopathy (n = 16), and others. Paracorporeal continuous-flow pump was the most frequently implanted (n = 27). Most of the devices were implanted in patients with INTERMACS profile 1 (n = 24). The median duration on VAD was 22 days (range 2-254). The proportion of patients attaining positive outcomes (alive on device, bridge to transplantation or recovery) was 72.7% at 1 month, 67.7% at 3 months, and 67.7% at 6 months. Most of the deaths on device occurred within the first month post-implant (n = 9), with neurological complications being the most frequent cause of death. All recovered cases were successfully weaned off the device within the first month of implantation.

CONCLUSION

We demonstrated a favorable outcome in pediatric patients supported with VAD at our institution.

Outcomes of Over 1000 Heart Transplants Using Hepatitis C-Positive Donors in the Modern Era

BACKGROUND

Advances in hepatitis C virus (HCV) treatment and the ongoing opioid epidemic have made HCV-positive donors increasingly available for heart transplantation (HT). This analysis reports outcomes of over 1000 HCV-positive HTs in the United States in the modern era.

METHODS

The United Network of Organ Sharing registry was used to identify HTs between 2015 and 2021. Recipients were grouped by donor HCV status and by nucleic acid amplification test (NAT) positivity. The primary outcome was 1-year mortality, and secondary outcomes included 3-year mortality. A subanalysis compared HCV-positive HT outcomes between NAT-positive and NAT-negative donors. Risk adjustment was performed using Cox regression. Kaplan-Meier analysis was used to estimate survival.

RESULTS

The frequency of HCV-positive HT increased from 0.12% of HTs in 2015 to 12.9% in 2021 (P < .001). Of 16,648 HTs, 1170 (7.0%) used an organ from an HCV-positive donor. Recipients of HCV-positive organs were more likely to be HCV seropositive, older, and White. Unadjusted 1- and 3-year survival rates were not significantly different between recipients of HCV-negative and HCV-positive organs. After risk adjustment HCV-positive donor status was not associated with an elevated risk for 1-year (hazard ratio, 0.92; 95% CI, 0.71-1.19; P = .518) or 3-year mortality. Among HCV-positive HTs 772 (61.7%) were NAT positive. After risk adjustment NAT positivity did not impact 1-year mortality.

CONCLUSIONS

The proportion of HCV-positive HTs has increased over 100-fold in recent years. This analysis of the US experience demonstrates that recipients of HCV-positive hearts, including those that are NAT positive, have acceptable outcomes with similar early to midterm survival as recipients of HCV-negative organs.

Interrupted Time Series Analysis of Donor Heart Use Before and After the 2018 UNOS Heart Allocation Policy Change

BACKGROUND

Donor heart scarcity remains the fundamental barrier to increased transplant access. We examined whether 2018 United Network for Organ Sharing (UNOS) policy changes have had an impact on donor heart acceptance rates.

METHODS AND RESULTS

We performed an interrupted time series analysis in UNOS to evaluate for abrupt changes in donor heart-acceptance rates associated with the new policy. All adult donor offers were evaluated between 2015 and 2021 (n = 66,654 donors). Donor volumes and transplants increased during this period, but the donor acceptance rate declined significantly from 31% in quarter 3 of 2018 to 26% acceptance in quarter 3 of 2021 (slope change -0.4% per quarter; P < 0.001). We identified 2 trends associated with this decline: (1) a growing number of donors with high-risk features, and (2) decreased acceptance of donors with certain high-risk features in the new allocation system.

CONCLUSIONS

Heart transplant volumes have increased in recent years as a result of increased donor volumes, but donor heart acceptance rates began decreasing under the current allocation system. Changes in the donor pool and acceptance patterns for certain donor-risk features may explain this shift and warrant further evaluation to maximize donor heart use.

Disparities in vaccination rates in solid organ transplant patients

INTRODUCTION

Vaccinations against preventable respiratory infections such as Streptococcus pneumoniae and influenza are important in immunosuppressed solid organ transplant (SOT) recipients. Little is known about the role of age, race, ethnicity, sex, and sociodemographic factors including rurality, or socioeconomic status (SES) associated with vaccine uptake in this population.

METHODS

We conducted a population-based study using the Rochester Epidemiology Project, a medical records linkage system, to assess socioeconomic and demographic factors associated with influenza and pneumococcal vaccination rates among adult recipients of solid organ transplantation (aged 19-64 years) living in four counties in southeastern Minnesota. Vaccination data were obtained from the Minnesota Immunization Information Connection from June 1, 2010 to June 30, 2020. Vaccination rate was assessed with Poisson and logistic regression models.

RESULTS

A total of 468 SOT recipients were identified with an overall vaccination rate of 57%-63% for influenza and 56% for pneumococcal vaccines. As expected, vaccination for pneumococcal vaccine positively correlated with influenza vaccination. Rural patients had decreased vaccination in both compared to urban patients, even after adjusting for age, sex, race, ethnicity, and SES. Although the population was mostly White and non-Hispanic, neither vaccination differed by race or ethnicity, but influenza vaccination did by SES. Among organ transplant groups, liver and lung recipients were least vaccinated for influenza, and heart recipients were least up-to-date on pneumococcal vaccines.

CONCLUSIONS

Rates of vaccination were below national goals. Rurality was associated with undervaccination. Further investigation is needed to understand and address barriers to vaccination among transplant recipients.

Does donor treatment with inotropes and/or vasopressors impact post-transplant outcomes?

PURPOSE

The purpose was to evaluate the effects of the most commonly used cardiac donor inotropes/vasopressors on subsequent post-heart transplant survival.

METHODS

Adult heart transplant recipients from January 2000 to June 2022 were identified in the United Network for Organ Sharing (UNOS) database. Exclusion criteria included: multiorgan transplants, donor age < 15, and recipient age < 18. Donors receiving vasoactive medications at the time of procurement were compared to donors not receiving these medications. Those on vasoactive medications were stratified by medication: phenylephrine, dopamine, dobutamine, norepinephrine and epinephrine, the combination of these agents, and the concomitant administration of vasopressin with any single agent alone or in combination. The primary area of interest was short-and-long-term survival. Survival at 30 days, 1 year, and long-term (Median = 13.6 years) was compared using logistic and Cox models to quantify survival endpoints.

RESULTS

A total of 45,198 donors met inclusion criteria and had data on the use of vasoactive agents available. Mean donor age was 32.3 years with 71% male. Vasoactive medications and potential combinations included phenylephrine in 8156 donors (18.0%), dopamine in 9550 (21.1%), dobutamine in 718 (1.6%), epinephrine in 332 (.73%), and norepinephrine in 4854 (10.7%). A total of 25,856 donors (57.2%) were receiving vasopressin at the time of procurement. There was no impact of donor inotropes on 30-day survival. Donors receiving one inotrope and no vasopressin were associated with increased 1 year mortality (OR 1.14; p = .021), as were donors receiving 2+ inotropes and no vasopressin (OR 1.26; p = .006). For individual agents, 1 year mortality was increased for dopamine (OR 1.11; p = .042) and epinephrine (OR 1.59; p = .004).

CONCLUSIONS

There is no difference in heart transplant recipient survival at 30 days when the donor is receiving inotropes without vasopressin at the time of procurement. Inotropic support without vasopressin is associated with greater 1 year mortality. The impact of donor inotropic support on long term heart transplant survival, and the interaction with vasopressin warrants further study.

Transition to heart transplantation in post-myocardial infarction ventricular septal rupture: a systematic review

Post-myocardial infarction ventricular septal rupture (MI-VSR) remains a dreadful complication with dismal prognosis. Surgical repair is the primary treatment strategy, whereas the role of heart transplantation (HT) as a primary option in MI-VSR is limited to case reports (CRs). We performed a systematic review of CRs to describe in-hospital mortality, and survival at 6 and 12 months in adult patients with MI-VSR treated with HT as a primary or bailout strategy. We performed a comprehensive search of Web of Science, PubMed, and Ovid Medline. The last search was completed on March 10, 2020. An aggregated score based on the CARE case report guideline was used to assess the quality of the CRs. We included CRs that described adult patients with MI-VSR treated with HT as a primary or bailout strategy. A total of 14 CRs between 1994 and 2015 were included, retrieving and analyzing the characteristics of 17 patients. A total of 12 patients underwent HT, with HT being the primary strategy in 8 patients and a bailout strategy for 4 patients following initial surgical repair, while 5 patients died awaiting HT under mechanical circulatory support (MCS), accounting for the total in-hospital mortality of this series (29%). Regarding long-term outcomes, 6 patients were reported to be alive at 6 months and 1 year after HT, while information was missing in the remaining 6 patients. In conclusion, HT supported by the use of temporary and durable MCS as a bridge to HT could be a feasible primary or bailout strategy to reduce the high in-hospital mortality of patients with MI-VSR.