Primary graft dysfunction after heart transplantation: a thorn amongst the roses

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.

Itaconate as a key player in cardiovascular immunometabolism

Cardiovascular diseases (CVDs) are the leading cause of death globally, resulting in a major health burden. Thus, an urgent need exists for exploring effective therapeutic targets to block progression of CVDs and improve patient prognoses. Immune and inflammatory responses are involved in the development of atherosclerosis, ischemic myocardial damage responses and repair, calcification, and stenosis of the aortic valve. These responses can involve both large and small blood vessels throughout the body, leading to increased blood pressure and end-organ damage. While exploring potential avenues for therapeutic intervention in CVDs, researchers have begun to focus on immune metabolism, where metabolic changes that occur in immune cells in response to exogenous or endogenous stimuli can influence immune cell effector responses and local immune signaling. Itaconate, an intermediate metabolite of the tricarboxylic acid (TCA) cycle, is related to pathophysiological processes, including cellular metabolism, oxidative stress, and inflammatory immune responses. The expression of immune response gene 1 (IRG1) is upregulated in activated macrophages, and this gene encodes an enzyme that catalyzes the production of itaconate from the TCA cycle intermediate, cis-aconitate. Itaconate and its derivatives have exerted cardioprotective effects through immune modulation in various disease models, such as ischemic heart disease, valvular heart disease, vascular disease, heart transplantation, and chemotherapy drug-induced cardiotoxicity, implying their therapeutic potential in CVDs. In this review, we delve into the associated signaling pathways through which itaconate exerts immunomodulatory effects, summarize its specific roles in CVDs, and explore emerging immunological therapeutic strategies for managing CVDs.

Usefulness of biomarkers to predict prognosis after heart transplant

INTRODUCTION AND OBJECTIVES

Heart transplant (HT) represents a major physiological stress, resulting in elevated levels of analytical biomarkers. This study aimed to determine whether changes in biomarker levels after HT can identify patients with a poor prognosis.

METHODS

A prospective longitudinal noninterventional study was conducted in 149 consecutive patients undergoing HT from July 2017 to July 2023. Biomarkers were assessed before HT and at 6, 24, 48, 72, and 96hours after HT. The biomarkers analyzed were high-sensitivity troponin T, N-terminal pro-B-type natriuretic peptide (NT-proBNP), creatinine, and lactic acid. The primary outcome was a composite of death and severe primary graft failure (PGF).

RESULTS

NT-proBNP and troponin levels remained highly elevated throughout the period and stabilized from the first 24hours post-HT. Lactate levels stabilized after the first 24hours, and creatinine from the second day onward. Exitus occurred in 23 (15%) of the patients, and severe PGF in 26 (17%). All biomarkers were significantly associated with the incidence of the combined event (P <.0001). Receiver operating characteristic curve analysis at 24hours showed significant areas under the curve (P=.0001). The greatest discriminatory power was observed for the NT-proBNP curve. A value of 10 000 pg/mL had a sensitivity of 90% and specificity of 80%.

CONCLUSIONS

A significant elevation of post-HT analytical biomarkers was associated with mortality and/or severe PGF. Among the biomarkers analyzed, NT-proBNP was the most accurate in classifying patients.

Early Outcomes in Patients With LVAD Undergoing Heart Transplant via Use of the SherpaPak Cardiac Transport System

BACKGROUND

Heart transplant (HT) in recipients with left ventricular assist devices (LVADs) is associated with poor early post-HT outcomes, including primary graft dysfunction (PGD). As complicated heart explants in recipients with LVADs may produce longer ischemic times, innovations in donor heart preservation may yield improved post-HT outcomes. The SherpaPak Cardiac Transport System is an organ preservation technology that maintains donor heart temperatures between 4 °C and 8 °C, which may minimize ischemic and cold-induced graft injuries. This analysis sought to identify whether the use of SherpaPak versus traditional cold storage was associated with differential outcomes among patients with durable LVAD undergoing HT.

METHODS

Global Utilization and Registry Database for Improved Heart Preservation-Heart (NCT04141605) is a multicenter registry assessing post-HT outcomes comparing 2 methods of donor heart preservation: SherpaPak versus traditional cold storage. A retrospective review of all patients with durable LVAD who underwent HT was performed. Outcomes assessed included rates of PGD, post-HT mechanical circulatory support use, and 30-day and 1-year survival.

RESULTS

SherpaPak (n=149) and traditional cold storage (n=178) patients had similar baseline characteristics. SherpaPak use was associated with reduced PGD (adjusted odds ratio, 0.56 [95% CI, 0.32-0.99]; P=0.045) and severe PGD (adjusted odds ratio, 0.31 [95% CI, 0.13-0.75]; P=0.009), despite an increased total ischemic time in the SherpaPak group. Propensity matched analysis also noted a trend toward reduced intensive care unit (SherpaPak 7.5±6.4 days versus traditional cold storage 11.3±18.8 days; P=0.09) and hospital (SherpaPak 20.5±11.9 days versus traditional cold storage 28.7±37.0 days; P=0.06) lengths of stay. The 30-day and 1-year survival was similar between groups.

CONCLUSIONS

SherpaPak use was associated with improved early post-HT outcomes among patients with LVAD undergoing HT. This innovation in preservation technology may be an option for HT candidates at increased risk for PGD.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04141605.

Ex Vivo Gene Therapy in Organ Transplantation: Considerations and Clinical Translation

Ex vivo machine perfusion (EVMP) is rapidly growing in utility during solid organ transplantation. This form of organ preservation is transforming how organs are allocated and expanding the definition of what is considered a suitable organ for transplantation in comparison with traditional static cold storage. All major organs (heart, lung, liver, kidney) have been influenced by this advanced method of organ preservation. This technology also serves as an unprecedented platform for effective administration of advanced therapeutics, including gene therapies, during organ transplantation to optimize and recondition organs ex vivo in an isolated manner. Applying gene therapy interventions through EVMP introduces different considerations and challenges that are unique from gene therapies designed for systemic administration. Considerations involving vector (choice, dose, toxicity), perfusate composition, and perfusion circuit components should be evaluated when developing a gene therapy to administer in this setting. This review explores these aspects and discusses clinical applications in transplantation where gene therapy interventions can be developed relevant to heart, lung, liver, and kidney donor grafts.

Mortality and morbidity after combined heart and liver transplantation in the failing Fontan: An updated dual center retrospective study

INTRODUCTION

As the adult Fontan population with Fontan associated liver disease continues to increase, more patients are being referred for transplantation, including combined heart and liver transplantation.

METHODS

We report updated mortality and morbidity outcomes after combined heart and liver transplant in a retrospective cohort series of 40 patients (age 14 to 49 years) with Fontan circulation across two centers from 2006-2022.

RESULTS

The 30-day, 1-year, 5-year and 10-year survival rate was 90%, 80%, 73% and 73% respectively. Sixty percent of patients met a composite comorbidity of needing either post-transplant mechanical circulatory support, renal replacement therapy or tracheostomy. Cardiopulmonary bypass time > 283 min (4.7 h) and meeting the composite comorbidity were associated with mortality by Kaplan Meier analysis.

CONCLUSION

Further study to mitigate early mortality and the above comorbidities as well as the high risk of bleeding and vasoplegia in this patient population is warranted.

End-stage heart failure: The future of heart transplant and artificial heart

In the last decades, outcomes significantly improved for both heart transplantation and LVAD. Heart transplantation remains the gold standard for the treatment of end stage heart failure and will remain for many years to come. The most relevant limitations are the lack of grafts and the effects of long-term immunosuppressive therapy that involve infectious, cancerous and metabolic complications despite advances in immunosuppression management. Mechanical circulatory support has an irreplaceable role in the treatment of end-staged heart failure, as bridge to transplant or as definitive implantation in non-transplant candidates. Although clinical results do not overcome those of HTx, improvement in the new generation of devices may help to reach the equipoise between the two therapies. This review will go through the evolution, current status and perspectives of both therapeutics.

ProtekDuo percutaneous ventricular support system-physiology and clinical applications

The ProtekDuo (LivaNova, London, UK) cannula is a dual-lumen device, typically inserted into the right internal jugular (IJ) vein through a percutaneous approach, with fluoroscopy or ultrasound guidance. When connected to a pump, such as the TandemHeart (LivaNova, London, UK) or CentriMag (Abbott, Pleasanton, CA, USA), it can function as a right ventricular (RV) mechanical circulatory support (MCS). When an oxygenator is also added [veno-pulmonary (V-P)], it can provide extracorporeal membrane oxygenation (ECMO) support. This review aims to provide a comprehensive overview of the device's physiology and clinical applications. In the setting of RV failure (RVF), the ProtekDuo cannula, with its outflow in the main pulmonary artery (PA), can bypass the failing RV, improving pulmonary flow, left atrial (LA) filling pressures, and left ventricular (LV) preload. This can also reduce ventricular interdependence and leftward shift of the interventricular septum that occurs in RVF. In this review, the key sections expand on the use of the ProtekDuo cannula in the management of critically ill patients, specifically, the use of ProtekDuo for RV myocardial infarction (MI) RVF, LV assist device (LVAD) implantation-associated RVF, RVF post-heart transplantation, temporary biventricular MCS as bridge to recovery (ECpella 2.0 or PROpella), biventricular support as bridge to recovery or decision, isolated LV failure, post lung transplantation (LT) care, and other miscellaneous clinical scenarios. ProtekDuo is an important tool in the armory of RVF management. The ProtekDuo system is expected to gain more popularity given its clear advantages such as groin-free approach allowing for mobility, easy percutaneous deployment, compatibility with various pumps and oxygenators, and the versatility to be integrated in numerous configurations. In an era of expanding MCS options, further research is needed to better understand the optimal tool for specific patient subsets.

The Use of Impella 5.5 for Donor-Heart Hemodynamic Support in Heart Transplantation

Primary graft dysfunction is a feared complication and cause of mortality post-heart transplant. Primary graft dysfunction may require mechanical circulatory support, such as venoarterial extracorporeal membrane oxygenation, which carries its own risk for complications. We developed a new mechanical circulatory support method for patients who underwent heart transplant bridged with Impella 5.5, which was then placed into the donor heart. Among 12 heart transplants, four required Impella 5.5 support. The average age was 55.8 years. The mean duration for postoperative mechanical circulatory support was 3.8 days, ranging from 2 to 5 days. No patients developed severe right ventricular dysfunction. In our limited study, complications and mortality associated with the replanted Impella 5.5 were both 0%.

The importance of timing in postcardiotomy venoarterial extracorporeal membrane oxygenation: A descriptive multicenter observational study

OBJECTIVES

Postcardiotomy extracorporeal membrane oxygenation (ECMO) can be initiated intraoperatively or postoperatively based on indications, settings, patient profile, and conditions. The topic of implantation timing only recently gained attention from the clinical community. We compare patient characteristics as well as in-hospital and long-term survival between intraoperative and postoperative ECMO.

METHODS

The retrospective, multicenter, observational Postcardiotomy Extracorporeal Life Support (PELS-1) study includes adults who required ECMO due to postcardiotomy shock between 2000 and 2020. We compared patients who received ECMO in the operating theater (intraoperative) with those in the intensive care unit (postoperative) on in-hospital and postdischarge outcomes.

RESULTS

We studied 2003 patients (women: 41.1%; median age: 65 years; interquartile range [IQR], 55.0-72.0). Intraoperative ECMO patients (n = 1287) compared with postoperative ECMO patients (n = 716) had worse preoperative risk profiles. Cardiogenic shock (45.3%), right ventricular failure (15.9%), and cardiac arrest (14.3%) were the main indications for postoperative ECMO initiation, with cannulation occurring after (median) 1 day (IQR, 1-3 days). Compared with intraoperative application, patients who received postoperative ECMO showed more complications, cardiac reoperations (intraoperative: 19.7%; postoperative: 24.8%, P = .011), percutaneous coronary interventions (intraoperative: 1.8%; postoperative: 3.6%, P = .026), and had greater in-hospital mortality (intraoperative: 57.5%; postoperative: 64.5%, P = .002). Among hospital survivors, ECMO duration was shorter after intraoperative ECMO (median, 104; IQR, 67.8-164.2 hours) compared with postoperative ECMO (median, 139.7; IQR, 95.8-192 hours, P < .001), whereas postdischarge long-term survival was similar between the 2 groups (P = .86).

CONCLUSIONS

Intraoperative and postoperative ECMO implantations are associated with different patient characteristics and outcomes, with greater complications and in-hospital mortality after postoperative ECMO. Strategies to identify the optimal location and timing of postcardiotomy ECMO in relation to specific patient characteristics are warranted to optimize in-hospital outcomes.

The role of CD38 in ischemia reperfusion injury in cardiopulmonary bypass and thoracic transplantation: a narrative review

Background and Objective

Ischemia reperfusion injury (IRI) is often the underlying cause of endothelium breakdown and damage in cardiac or transplantation operations, which can lead to disastrous post-operative consequences. Recent studies of cluster of differentiation 38 (CD38) have identified its critical role in IRI. Our objective is to provide a comprehensive overview of CD38-mediated axis, pathways, and potential CD38 translational therapies for reducing inflammation associated with cardiopulmonary bypass (CPB) or thoracic transplantation and IRI.

Methods

We conducted a review of the literature by performing a search of the PubMed database on 2 April 2023. To find relevant publications on CD38, we utilized the MeSH terms: "CD38" AND "Ischemia" OR "CD38" AND "Transplant" OR "CD38" AND "Heart" from 1990-2023. Additional papers were included if they were felt to be relevant but were not captured in the MeSH terms. We found 160 papers that met this criterion, and following screening, exclusion and consensus a total of 36 papers were included.

Key Content and Findings

CD38 is most notably a nicotine adenine dinucleotide (NAD)+ glycohydrolase (NADase), and a generator of Ca2+ signaling secondary messengers. Ultimately, the release of these secondary messengers leads to the activation of important mediators of cellular death. In the heart and during thoracic transplantation, this pathway is intimately involved in a wide variety of injuries; namely the endothelium. In the heart, activation generally results in vasoconstriction, poor myocardial perfusion, and ultimately poor cardiac function. CD38 activation also prevents the accumulation of atherosclerotic disease. During transplantation, intracellular activation leads to infiltration of recipient innate immune cells, tissue edema, and ultimately primary graft dysfunction (PGD). Specifically, in heart transplantation, extracellular activation could be protective and improve allograft survival.

Conclusions

The knowledge gap in understanding the molecular basis of IRI has prevented further development of novel therapies and treatments. The possible interaction of CD38 with CD39 in the endothelium, and the modulation of the CD38 axis may be a pathway to improve cardiovascular outcomes, heart and lung donor organ quality, and overall longevity.

Understanding and Investigating Sex-Based Differences in Heart Transplantation: A Call to Action

Women represent only about 25% of heart transplant recipients annually. Although the number of women living with advanced heart failure remains unknown, epidemiologic research suggests that more women should be receiving advanced heart failure therapies. Sex differences in risk factors, presentation, response to pharmacotherapy, and outcomes in heart failure have been well described. Yet, less is known about sex differences in heart transplant candidate selection, waitlist management, donor selection, perioperative considerations, and post-transplant management and outcomes. The purpose of this review was to summarize the existing published reports related to sex differences in heart transplantation, highlighting areas in which sex-based considerations are well described and supported by available evidence, and emphasizing topics that require further study.

Graft preservation in heart transplantation: current approaches

Heart transplantation (HTx) represents the current best surgical treatment for patients affected by end-stage heart failure. However, with the improvement of medical and interventional therapies, the population of HTx candidates is increasingly old and at high-risk for mortality and complications. Moreover, the use of "extended donor criteria" to deal with the shortage of donors could increase the risk of worse outcomes after HTx. In this setting, the strategy of donor organ preservation could significantly affect HTx results. The most widely used technique for donor organ preservation is static cold storage in ice. New techniques that are clinically being used for donor heart preservation include static controlled hypothermia and machine perfusion (MP) systems. Controlled hypothermia allows for a monitored cold storage between 4°C and 8°C. This simple technique seems to better preserve the donor heart when compared to ice, probably avoiding tissue injury due to sub-zero °C temperatures. MP platforms are divided in normothermic and hypothermic, and continuously perfuse the donor heart, reducing ischemic time, a well-known independent risk factor for mortality after HTx. Also, normothermic MP permits to evaluate marginal donor grafts, and could represent a safe and effective technique to expand the available donor pool. However, despite the increasing number of donor hearts preserved with these new approaches, whether these techniques could be considered superior to traditional CS still represents a matter of debate. The aim of this review is to summarize and critically assess the available clinical data on donor heart preservation strategies employed for HTx.

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

Introduction

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

Methods

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

Results

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

Conclusion

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

Patient and Management Variables Associated With Survival After Postcardiotomy Extracorporeal Membrane Oxygenation in Adults: The PELS-1 Multicenter Cohort Study

Background Extracorporeal membrane oxygenation (ECMO) has been increasingly used for postcardiotomy cardiogenic shock, but without a concomitant reduction in observed in-hospital mortality. Long-term outcomes are unknown. This study describes patients' characteristics, in-hospital outcome, and 10-year survival after postcardiotomy ECMO. Variables associated with in-hospital and postdischarge mortality are investigated and reported. Methods and Results The retrospective international multicenter observational PELS-1 (Postcardiotomy Extracorporeal Life Support) study includes data on adults requiring ECMO for postcardiotomy cardiogenic shock between 2000 and 2020 from 34 centers. Variables associated with mortality were estimated preoperatively, intraoperatively, during ECMO, and after the occurrence of any complications, and then analyzed at different time points during a patient's clinical course, through mixed Cox proportional hazards models containing fixed and random effects. Follow-up was established by institutional chart review or contacting patients. This analysis included 2058 patients (59% were men; median [interquartile range] age, 65.0 [55.0-72.0] years). In-hospital mortality was 60.5%. Independent variables associated with in-hospital mortality were age (hazard ratio [HR], 1.02 [95% CI, 1.01-1.02]) and preoperative cardiac arrest (HR, 1.41 [95% CI, 1.15-1.73]). In the subgroup of hospital survivors, the overall 1-, 2-, 5-, and 10-year survival rates were 89.5% (95% CI, 87.0%-92.0%), 85.4% (95% CI, 82.5%-88.3%), 76.4% (95% CI, 72.5%-80.5%), and 65.9% (95% CI, 60.3%-72.0%), respectively. Variables associated with postdischarge mortality included older age, atrial fibrillation, emergency surgery, type of surgery, postoperative acute kidney injury, and postoperative septic shock. Conclusions In adults, in-hospital mortality after postcardiotomy ECMO remains high; however, two-thirds of those who are discharged from hospital survive up to 10 years. Patient selection, intraoperative decisions, and ECMO management remain key variables associated with survival in this cohort. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03857217.

Clinical trends, risk factors, and temporal effects of post-transplant dialysis on outcomes following orthotopic heart transplantation in the 2018 United States heart allocation system

BACKGROUND

This study evaluated the current clinical trends, risk factors, and temporal effects of post-transplant dialysis on outcomes following orthotopic heart transplantation after the 2018 United States adult heart allocation policy change.

METHODS

The United Network for Organ Sharing (UNOS) registry was queried to analyze adult orthotopic heart transplant recipients after the October 18, 2018 heart allocation policy change. The cohort was stratified according to the need for post-transplant de novo dialysis. The primary outcome was survival. Propensity score-matching was performed to compare the outcomes between 2 similar cohorts with and without post-transplant de novo dialysis. The impact of post-transplant dialysis chronicity was evaluated. Multivariable logistic regression was performed to identify risk factors for post-transplant dialysis.

RESULTS

A total of 7,223 patients were included in this study. Out of these, 968 patients (13.4%) developed post-transplant renal failure requiring de novo dialysis. Both 1-year (73.2% vs 94.8%) and 2-year (66.3% vs 90.6%) survival rates were lower in the dialysis cohort (p < 0.001), and the lower survival rates persisted in a propensity-matched comparison. Recipients requiring only temporary post-transplant dialysis had significantly improved 1-year (92.5% vs 71.6%) and 2-year (86.6 % vs 52.2%) survival rates compared to the chronic post-transplant dialysis group (p < 0.001). Multivariable analysis demonstrated low pretransplant estimated glomerular filtration (eGFR) and bridge with extracorporeal membrane oxygenation (ECMO) were strong predictors of post-transplant dialysis.

CONCLUSIONS

This study demonstrates that post-transplant dialysis is associated with significantly increased morbidity and mortality in the new allocation system. Post-transplant survival is affected by the chronicity of post-transplant dialysis. Low pretransplant eGFR and ECMO are strong risk factors for post-transplant dialysis.

Successful Reuse of a Donor Heart

At a time when transplantable organs are in a shortage, few cases have noted the reuse of donor hearts in a second recipient in an effort to expand the donor network. Here, we present a case in which an O Rh-positive donor heart was first transplanted into a B Rh-positive recipient and later successfully retransplanted into a second O Rh-positive recipient 10 days after the initial transplant at the same medical center. On postoperative day 1, the first recipient, a 21-year-old man with nonischemic cardiomyopathy, sustained a devastating cerebrovascular accident with progression to brain death. With preserved left ventricle and mildly depressed right ventricle function, the heart was allocated to the second recipient, a 63-year-old male patient with familial restrictive cardiomyopathy. The bicaval technique was used, and the total ischemic time was 100 minutes. His postoperative course was uncomplicated with no evidence of rejection on 3 endomyocardial biopsies. Follow-up transthoracic echocardiogram revealed a left ventricular ejection fraction of 60% to 70%. Seven months posttransplant, the second recipient was doing well with appropriate left and right ventricular function. With careful organ selection, short ischemic time, and proper postoperative care, retransplant of donor hearts may be an option for select patients in need of heart transplant.

Thoracic organ machine perfusion: A review of concepts with a focus on reconditioning therapies

Thoracic organ transplantation, including lung, heart, and heart-lung transplants are highly regarded as gold standard treatments for patients suffering from heart failure or chronic end stage lung conditions. The relatively high prevalence of conditions necessitating thoracic organ transplants combined with the lack of available organs has resulted in many either dying or becoming too ill to receive a transplant while on the waiting list. There is a dire need to increase both the number of organs available and the utilization of such organs. Improved preservation techniques beyond static storage have shown great potential to lengthen the current period of viability of thoracic organs while outside the body, promising better utilization rates, increased donation distance, and improved matching of donors to recipients. Ex-situ organ perfusion (ESOP) can also make some novel therapeutic strategies viable, and the combination of the ESOP platform with such reconditioning therapies endeavors to better improve functional preservation of organs in addition to making more organs viable for transplantation. Given the abundance of clinical and pre-clinical studies surrounding reconditioning of thoracic organs in combination with ESOP, we summarize in this review important concepts and research regarding thoracic organ machine perfusion in combination with reconditioning therapies.

Primary graft dysfunction following lung transplantation: From pathogenesis to future frontiers

Lung transplantation is the treatment of choice for patients with end-stage lung disease. Currently, just under 5000 lung transplants are performed worldwide annually. However, a major scourge leading to 90-d and 1-year mortality remains primary graft dysfunction. It is a spectrum of lung injury ranging from mild to severe depending on the level of hypoxaemia and lung injury post-transplant. This review aims to provide an in-depth analysis of the epidemiology, pathophysiology, risk factors, outcomes, and future frontiers involved in mitigating primary graft dysfunction. The current diagnostic criteria are examined alongside changes from the previous definition. We also highlight the issues surrounding chronic lung allograft dysfunction and identify the novel therapies available for ex-vivo lung perfusion. Although primary graft dysfunction remains a significant contributor to 90-d and 1-year mortality, ongoing research and development abreast with current technological advancements have shed some light on the issue in pursuit of future diagnostic and therapeutic tools.

Approach to optimal assessment of right ventricular remodelling in heart transplant recipients: insights from myocardial work index, T1 mapping, and endomyocardial biopsy

AIMS

Right ventricular (RV) dysfunction is an important cause of graft failure after heart transplantation (HTx). We sought to investigate relative merits of echocardiographic tools and cardiac magnetic resonance (CMR) with T1 mapping for the assessment of functional adaptation and remodelling of the RV in HTx recipients.

METHODS AND RESULTS

Sixty-one complete data set of echocardiography, CMR, right heart catheterization, and biopsy were obtained. Myocardial work index (MWI) was quantified by integrating longitudinal strain (LS) with invasively measured pulmonary artery pressure. CMR derived RV volumes, T1 time, and extracellular volume (ECV) were quantified. Endomyocardial biopsy findings were used as the reference standard for myocardial microstructural changes. In HTx recipients who never had a previous allograft rejection, longitudinal function parameters were lower than healthy organ donors, while ejection fraction (EF) (52.0 ± 8.7%) and MWI (403.2 ± 77.2 mmHg%) were preserved. Rejection was characterized by significantly reduced LS, MWI, longer T1 time, and increased ECV that improved after recovery, whereas RV volumes and EF did not change MWI was the strongest determinant of rejection related myocardial damage (area under curve: 0.812, P < 0.0001, 95% CI: 0.69-0.94) with good specificity (77%), albeit modest sensitivity. In contrast, T1 time and ECV were sensitive (84%, both) but not specific to detect subclinical RV damage.

CONCLUSION

Subclinical adaptive RV remodelling is characterized by preserved RV EF despite longitudinal function abnormalities, except for MWI. While ultrastructural damage is reflected by MWI, ECV, and T1 time, only MWI has the capability to discriminate functional adaptation from transition to subclinical structural damage.

Metabolic reprogramming by immune-responsive gene 1 up-regulation improves donor heart preservation and function

Preservation quality of donor hearts is a key determinant of transplant success. Preservation duration beyond 4 hours is associated with primary graft dysfunction (PGD). Given transport time constraints, geographical limitations exist for donor-recipient matching, leading to donor heart underutilization. Here, we showed that metabolic reprogramming through up-regulation of the enzyme immune response gene 1 (IRG1) and its product itaconate improved heart function after prolonged preservation. Irg1 transcript induction was achieved by adding the histone deacetylase (HDAC) inhibitor valproic acid (VPA) to a histidine-tryptophan-ketoglutarate solution used for donor heart preservation. VPA increased acetylated H3K27 occupancy at the IRG1 enhancer and IRG1 transcript expression in human donor hearts. IRG1 converts aconitate to itaconate, which has both anti-inflammatory and antioxidant properties. Accordingly, our studies showed that Irg1 transcript up-regulation by VPA treatment increased nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) in mice, which was accompanied by increased antioxidant protein expression [hemeoxygenase 1 (HO1) and superoxide dismutase 1 (SOD1)]. Deletion of Irg1 in mice (Irg1^-/-) negated the antioxidant and cardioprotective effects of VPA. Consistent with itaconate's ability to inhibit succinate dehydrogenase, VPA treatment of human hearts increased itaconate availability and reduced succinate accumulation during preservation. VPA similarly increased IRG1 expression in pig donor hearts and improved its function in an ex vivo cardiac perfusion system both at the clinical 4-hour preservation threshold and at 10 hours. These results suggest that augmentation of cardioprotective immune-metabolomic pathways may be a promising therapeutic strategy for improving donor heart function in transplantation.

Severe primary graft dysfunction of the heart transplant is associated with increased plasma and intragraft proinflammatory cytokine expression

INTRODUCTION

Heart transplant results have constantly improved but primary left ventricle graft dysfunction (LV-PGD) remains a devastating complication early after transplantation. Donor and recipient systemic inflammatory response may be involved in immune activation of the transplant, and LV-PGD development. Here, we investigated donor and recipient plasma and intragraft cytokine profiles preoperatively and during LV-PGD and searched for predictive markers for LV-PGD.

METHODS

Donor and recipient plasma samples (n = 74) and myocardial biopsies of heart transplants (n = 64) were analyzed. Plasma and intragraft cytokine levels were determined by multiplexed and next-generation sequencing platforms, respectively. The development of LV-PGD during the first 24 hours, and graft function and mortality up to 1 year after transplantation, were examined.

RESULTS

Severe LV-PGD, but not mild or moderate LV-PGD, was significantly associated with early mortality, plasma high-sensitivity troponin elevation, and an increase in intragraft and plasma proinflammatory cytokines during reperfusion. Preoperative donor and recipient plasma cytokine levels failed to predict LV-PGD. Cytokine network analysis identified interleukins -6, -8, -10, and -18 as key players during reperfusion. Prolonged cold and total ischemia time, and increased need for red blood cell transfusions during operation were identified as clinical risk factors for severe LV-PGD.

CONCLUSIONS

Severe LV-PGD was associated with a poor clinical outcome. Donor and recipient plasma cytokine profile failed to predict LV-PGD, but severe LV-PGD was associated with an increase in post-reperfusion intragraft and recipient plasma proinflammatory cytokines. Identified key cytokines may be potential therapeutic targets to improve early and long-term outcomes after heart transplantation.

The Clinical Outcomes of Marginal Donor Hearts: A Single Center Experience

BACKGROUND AND OBJECTIVES

Although the shortage of donor is a common problem worldwide, a significant portion of unutilized hearts are classified as marginal donor (MD) hearts. However, research on the correlation between the MD and the prognosis of heart transplantation (HTx) is lacking. This study was conducted to investigate the clinical impact of MD in HTx.

METHODS

Consecutive 73 HTxs during 2014 and 2021 in a tertiary hospital were analyzed. MD was defined as follows; a donor age >55 years, left ventricular ejection fraction <50%, cold ischemic time >240 minutes, or significant cardiac structural problems. Preoperative characteristics and postoperative hemodynamic data, primary graft dysfunction (PGD), and the survival rate were analyzed. Risk stratification by Index for Mortality Prediction after Cardiac Transplantation (IMPACT) score was performed to examine the outcomes according to the recipient state. Each group was sub-divided into 2 risk groups according to the IMPACT score (low <10 vs. high ≥10).

RESULTS

A total of 32 (43.8%) patients received an organ from MDs. Extracorporeal membrane oxygenation was more frequent in the non-MD group (34.4% vs. 70.7, p=0.007) There was no significant difference in PGD, 30-day mortality and long-term survival between groups. In the subgroup analysis, early outcomes did not differ between low- and high-risk groups. However, the long-term survival was better in the low-risk group (p=0.01).

CONCLUSIONS

The outcomes of MD group were not significantly different from non-MD group. Particularly, in low-risk recipient, the MD group showed excellent early and long-term outcomes. These results suggest the usability of selected MD hearts without increasing adverse events.

Improved Outcomes in Severe Primary Graft Dysfunction After Heart Transplantation Following Donation After Circulatory Death Compared With Donation After Brain Death

BACKGROUND

Primary graft dysfunction (PGD), the leading cause of early mortality after heart transplantation, is more common following donation after circulatory death (DCD) than donation after brain death (DBD). We conducted a single-center, retrospective cohort study to compare the incidence, severity and outcomes of patients experiencing PGD after DCD compared to DBD heart transplantation.

METHODS AND RESULTS

Medical records were reviewed for all adult heart transplant recipients at our institution between March 2016 and December 2021. PGD was diagnosed within 24 hours after transplant according to modified International Society for Heart and Lung Transplant criteria. A total of 459 patients underwent isolated heart transplantation during the study period, 65 (14%) following DCD and 394 (86%) following DBD. The incidence of moderate or severe PGD in DCD and DBD recipients was 34% and 23%, respectively (P = 0.070). DCD recipients were more likely to experience severe biventricular PGD than DBD recipients (19% vs 7.4%; P = 0.004). Among patients with severe PGD, DCD recipients experienced shorter median (Q1, Q3) duration of post-transplant mechanical circulatory support (6 [4, 7] vs 9 [5, 14] days; P = 0.039), shorter median post-transplant hospital length of stay (17 [15, 29] vs 52 [26, 83] days; P = 0.004), and similar 60-day survival rates (100% [95% CI: 76.8%-100%] vs 80.0% [63.1%-91.6%]; P = 0.17) and overall survival (log-rank; P = 0.078) compared with DBD recipients.

CONCLUSIONS

DCD heart transplant recipients were more likely to experience severe, biventricular PGD than DBD recipients. Despite this, DCD recipients with severe PGD spent fewer days on mechanical circulatory support and in the hospital than similar DBD patients. These findings suggest that patterns of graft dysfunction and recovery may differ between donor types, and they support the expansion of the heart-donor pool with DCD.

Prediction Model for Contractile Function of Circulatory Death Donor Hearts Based on Microvascular Flow Shifts During Ex Situ Hypothermic Cardioplegic Machine Perfusion

Background Hearts procured from circulatory death donors (DCD) are predominantly maintained by machine perfusion (MP) with normothermic donor blood. Currently, DCD heart function is evaluated by lactate and visual inspection. We have shown that MP with the cardioplegic, crystalloid Custodiol-N solution is superior to blood perfusion to maintain porcine DCD hearts. However, no method has been developed yet to predict the contractility of DCD hearts after cardioplegic MP. We hypothesize that the shift of microvascular flow during continuous MP with a cardioplegic preservation solution predicts the contractility of DCD hearts. Methods and Results In a pig model, DCD hearts were harvested and maintained by MP with hypothermic, oxygenated Custodiol-N for 4 hours while myocardial microvascular flow was measured by Laser Doppler Flow (LDF) technology. Subsequently, hearts were perfused with blood for 2 hours, and left ventricular contractility was measured after 30 and 120 minutes. Various novel parameters which represent the LDF shift were computed. We used 2 combined LDF shift parameters to identify bivariate prediction models. Using the new prediction models based on LDF shifts, highest r² for end-systolic pressure was 0.77 (P=0.027), for maximal slope of pressure increment was 0.73 (P=0.037), and for maximal slope of pressure decrement was 0.75 (P=0.032) after 30 minutes of reperfusion. After 120 minutes of reperfusion, highest r² for end-systolic pressure was 0.81 (P=0.016), for maximal slope of pressure increment was 0.90 (P=0.004), and for maximal slope of pressure decrement was 0.58 (P=0.115). Identical prediction models were identified for maximal slope of pressure increment and for maximal slope of pressure decrement at both time points. Lactate remained constant and therefore was unsuitable for prediction. Conclusions Contractility of DCD hearts after continuous MP with a cardioplegic preservation solution can be predicted by the shift of LDF during MP.

Targeting IL-6 to prevent cardiac allograft rejection

Outcomes following heart transplantation remain suboptimal with acute and chronic rejection being major contributors to poor long-term survival. IL-6 is increasingly recognized as a critical pro-inflammatory cytokine involved in allograft injury and has been shown to play a key role in regulating the inflammatory and alloimmune responses following heart transplantation. Therapies that inhibit IL-6 signaling have emerged as promising strategies to prevent allograft rejection. Here, we review experimental and pre-clinical evidence that supports the potential use of IL-6 signaling blockade to improve outcomes in heart transplant recipients.

Optimizing Anastomoses Technique in Orthotopic Heart Transplantation: Comparison of Biatrial, Bicaval and Modified Bicaval Technique

Implantation techniques for orthotopic heart transplantation (HTx) have evolved over the centuries. Recently new approaches of modified bicaval techniques to minimize warm ischemia are gaining popularity in the literature. Between 2010 and 2022 n = 238 patients underwent HTx in our department. The recipients were retrospectively reviewed and divided regarding their anastomoses’ technique. Anastomoses were sutured either in biatrial (n = 37), bicaval (n = 191) or in a modified bicaval (n = 10) manner with suturing of the superior cava vein and A. pulmonalis anastomosis after removing the aortic cross-clamp during the reperfusion. Warm ischemia was 62 ± 11 min for biatrial, 66 ± 15 min for bicaval, but only 48 ± 10 min for modified bicaval technique (p < 0.001). The incidence of severe primary graft dysfunction (PGD) was comparable between biatrial (27.0%) and bicaval (28.8%) anastomoses. In contrast, in patients with modified bicaval technique PGD occurred only in a single patient (10.0%). The incidence of postoperative pacemaker implantation was 18.2% for biatrial compared to 3.0% for bicaval and 0.0% for modified bicaval technique (p = 0.01). The modified bicaval technique enables to decrease the crucial warm ischemia during HTx compared to both biatrial and regular bicaval techniques. Therefore, we strongly recommend bicaval anastomoses, ideally in a modified manner.

Multicenter Registry Using Propensity Score Analysis to Compare a Novel Transport/Preservation System to Traditional Means on Postoperative Hospital Outcomes and Costs for Heart Transplant Patients

The standard method for cardiac allograft preservation for the past 50 years has been static storage using crushed ice. A heart transplant transportation system designed to improve preservation quality with temperature monitoring, the Paragonix SherpaPak Cardiac Transport System (SCTS), was evaluated for its impact on postoperative costs relative to conventional ice storage. Observational US multicenter registry data collected during the August 2015 to November 2021 timeframe from 12 transplant hospitals were analyzed using logistic regression analysis and propensity matching to balance measured baseline covariates and to reduce selection bias. Hospital cost and outcome data post-transplant were then evaluated using various statistical methods. One hundred seventy-four (174) patients were identified resulting in 87 matches. Baseline characteristics were similar between groups. The SCTS group had a significantly lower proportion of ICU days on post-transplant mechanical circulatory support (p < 0.0001); significantly fewer patients on extracorporeal membrane oxygenation (p = 0.017); and significantly fewer patients experiencing severe primary graft dysfunction (PGD) (p = 0.03). Overall hospital plus mechanical circulatory support post-transplant costs were significantly lower by $26.7K in the CTS cohort (p = 0.03). Use of the SCTS is associated with improved clinical outcomes resulting in significantly lower overall hospital care costs.

Clinicopathological correlations in heart transplantation recipients complicated by death or re-transplantation

Purpose

This study aimed to identify and correlate pathological findings with clinical outcomes in patients after orthotopic heart transplantation (OHT) who either died or underwent a re-transplantation.

Methodology and study design

Single-center retrospective analysis of primary OHT patients who died or were re-transplanted between October 2012 and July 2021. Clinical data were matched with corresponding pathological findings from endomyocardial biopsies on antibody-mediated rejection, cellular rejection, and cardiac allograft vasculopathy. Re-assessment of available tissue samples was performed to investigate acute myocardial injury (AMI) as a distinct phenomenon. These were correlated with clinical outcomes, which included severe primary graft dysfunction. Patients were grouped according to the presence of AMI and compared.

Results

We identified 47 patients with truncated outcomes after the first OHT. The median age was 59 years, 36 patients (76%) were male, 25 patients (53%) had a prior history of cardiac operation, and 21 patients (45%) were supported with a durable assist device before OHT. Of those, AMI was identified in 22 (47%) patients (AMI group), and 25 patients had no AMI (non-AMI group). Groups were comparable in baseline and perioperative data. Histopathological observations in AMI group included a non-significant higher incidence of antibody-mediated rejection Grade 1 or higher (pAMR ≥ 1) (32% vs. 12%, P = 0.154), and non-significant lower incidence of severe acute cellular rejection (ACR ≥ 2R) (32% vs. 40%, P = 0.762). Clinical observations in the AMI group found a significantly higher occurrence of severe primary graft dysfunction (68% vs. 20%, P = 0.001) and a highly significant shorter duration from transplantation to death or re-transplantation (42 days [IQR 26, 120] vs. 1,133 days [711–1,664], P < 0.0001). Those patients had a significantly higher occurrence of cardiac-related deaths (64% vs. 24%, P = 0.020). No difference was observed in other outcomes.

Conclusion

In heart transplant recipients with a truncated postoperative course leading to either death or re-transplantation, AMI in endomyocardial biopsies was a common pathological phenomenon, which correlated with the clinical occurrence of severe primary graft dysfunction. Those patients had significantly shorter survival times and higher cardiac-related deaths. The presence of AMI suggests a truncated course after OHT.

Posttransplant Complications and Genetic Loci Involved in Telomere Maintenance in Heart Transplant Patients

Reaching critically short telomeres induces cellular senescence and ultimately cell death. Cellular senescence contributes to the loss of tissue function. We aimed to determine the association between variants within genes involved in telomere length maintenance, posttransplant events, and aortic telomere length in heart transplant patients. DNA was isolated from paired aortic samples of 383 heart recipients (age 50.7 ± 11.9 years) and corresponding donors (age 38.7 ± 12.0 years). Variants within the TERC (rs12696304), TERF2IP (rs3784929 and rs8053257), and OBCF1 (rs4387287) genes were genotyped, and telomere length was measured using qPCR. We identified similar frequencies of genotypes in heart donors and recipients. Antibody-mediated rejection (AMR) was more common (p < 0.05) in carriers of at least one G allele within the TERF2IP locus (rs3784929). Chronic graft dysfunction (CGD) was associated with the TERC (rs12696304) GG donor genotype (p = 0.05). The genetic risk score did not determine posttransplant complication risk prediction. No associations between the analyzed polymorphisms and telomere length were detected in either donor or recipient DNA. In conclusion, possible associations between donor TERF2IP (rs3784929) and AMR and between TERC (rs12696304) and CGD were found. SNPs within the examined genes were not associated with telomere length in transplanted patients.

Ferroptosis and its role in cardiomyopathy

Heart disease is the leading cause of death worldwide. Cardiomyopathy is a disease characterized by the heart muscle damage, resulting heart in a structurally and functionally change, as well as heart failure and sudden cardiac death. The key pathogenic factor of cardiomyopathy is the loss of cardiomyocytes, but the related molecular mechanisms remain unclear. Ferroptosis is a newly discovered regulated form of cell death, characterized by iron accumulation and lipid peroxidation during cell death. Recent studies have shown that ferroptosis plays an important regulatory roles in the occurrence and development of many heart diseases such as myocardial ischemia/reperfusion injury, cardiomyopathy and heart failure. However, the systemic association of ferroptosis and cardiomyopathy remains largely unknown and needs to be elucidated. In this review, we provide an overview of the molecular mechanisms of ferroptosis and its role in individual cardiomyopathies, highlight that targeting ferroptosis maybe a potential therapeutic strategy for cardiomyopathy therapy in the future.

Plasma Levels of SERCA2a as a Noninvasive Biomarker of Primary Graft Dysfunction After Heart Transplantation

BACKGROUND

Noninvasive detection of primary graft dysfunction (PGD) remains a major challenge. SERCA2a plays an important role in cardiac homeostasis and its dysregulation has been associated with ventricular dysfunction and rejection. This study aimed to determine the potential utility of plasma levels of SERCA2a as a biomarker of PGD.

METHODS

One hundred thirty-five plasma samples were collected from adult recipients 2-6 hours before heart transplantation (HT). Plasma concentrations of SERCA2a were determined using a specific sandwich ELISA. Variables related to the recipient, the donor, and the periprocedural were collected to determine a multivariate predictive model of PGD.

RESULTS

Levels of SERCA2a were decreased in patients who developed PGD (median 0.430 ng/mL [interquartile range, 0.260-0.945] versus 0.830 ng/mL [interquartile range, 0.582-1.052]; P = 0.001). Receiver operating characteristic curve analysis revealed that SERCA2a discriminated between patients with and without PGD (AUC = 0.682; P = 0.001), and a cutoff point ≥ 0.60 ng/mL was a protective independent predictor of PGD (odds ratio 0.215 [P = 0.004]). Three independent predictors of PGD in this study were reduced levels of pre-HT SERCA2a, increased bilirubin levels, and short-term mechanical circulatory support bridge to transplantation. The analysis of the receiver operating characteristic curve of the model obtained a significant AUC 0.788, P = 0.0001.

CONCLUSIONS

Our findings suggest that assessment of SERCA2a plasma levels may improve risk prediction for the occurrence of PGD and could be considered as a novel noninvasive biomarker in patients undergoing HT.

Heart Transplantation of the Elderly-Old Donors for Old Recipients: Can We Still Achieve Acceptable Results?

As society is ageing, an increasing prevalence of elderly heart failure patients will be expected. In order to increase the donor pool, acceptance of older donors might be a reasonable choice. All patients undergoing heart transplantation between 2010 and 2021 at a single department were retrospectively reviewed and divided into different study groups with regard to recipient (≤60 years (R^Y) or >60 years (R^O)) and donor age (≤50 years (D^Y) or >50 years (D^O). A total of n = 201 patients were included (D^Y/R^Y, n = 91; D^O/R^Y, n = 38; D^Y/R^O, n = 41; D^O/R^O, n = 31). Neither incidence of severe primary graft dysfunction (p = 0.64) nor adverse events, such as kidney failure (p = 0.27), neurological complications (p = 0.63), infections (p = 0.21) or acute graft rejection (p = 1.00), differed between the groups. However, one-year survival was impaired in the D^O/R^O group (56.0%) compared to the other groups (D^Y/R^Y: 86.1%, D^Y/R^O: 78.8%, D^O/R^Y: 74.2%, p = 0.02). Given the impaired one-year survival, acceptance of grafts from old donors for old recipients should be performed with caution and by experienced centres only. Nevertheless, because of the otherwise dismal prognosis of elderly heart failure patients, transplantation of patients may still improve the therapy outcome.

The Role of Echocardiography in the Management of Heart Transplant Recipients

Transthoracic echocardiography is the primary non-invasive modality for the investigation of heart transplant recipients. It is a versatile tool that provides comprehensive information on cardiac structure and function. Echocardiography is also helpful in diagnosing primary graft dysfunction and evaluating the effectiveness of therapeutic approaches for this condition. In acute rejection, echocardiography is useful with suspected cellular or antibody-mediated rejection, with findings confirmed and quantified by endomyocardial biopsy. For identifying chronic rejection, ultrasound has a more significant role and, in some specific patients (e.g., patients with renal failure), it may offer a role comparable to coronary angiography to identify cardiac allograft vasculopathy. This review highlights the usefulness of echocardiography in evaluating normal graft function and its role in the management of heart transplant recipients.

Multimodal temporary mechanically circulatory assistance for primary graft dysfunction after heart transplantation: a case report

Background

Primary graft dysfunction (PGD) remains a serious complication after heart transplantation (HTx). Although there is no therapy available, veno-arterial extracorporeal membrane oxygenation (VA-ECMO) may be a bailout strategy in selected cases. Especially in patients with severe biventricular failure, chances of survival remain poor.

Case summary

Here, we report a case of a 56-year-old patient suffering from severe PGD after HTx with biventricular failure (ejection fraction < 20%) who was successfully bridged to recovery of the donor graft by temporary multimodal mechanically circulatory assistance by combining both, VA-ECMO and a microaxial pump (Impella^®, Abiomed, Inc., Danvers, MA, USA), a concept also referred as ECMELLA. During ECMELLA support, the patient experienced multiple severe thoracic bleeding complications with need for four re-thoracotomies and temporary open chest situation. Nevertheless, ventricular function recovered and the patient could be weaned from mechanical circulatory support after 12 days. During follow-up, the patient recovered and was successfully discharged. After the following rehabilitation, the patient now shows no persistent signs of heart failure with normal biventricular function of the cardiac graft.

Discussion

ECMELLA may offer a therapeutic option for patients with severe PGD after HTx. Special awareness and further studies addressing targeted anticoagulation strategies for patients on dual-mechanical support are needed to diminish the incidence of bleeding complications.

Myocardial injury biomarkers at point of care for early identification of primary graft dysfunction after heart transplantation

INTRODUCTION

Primary graft dysfunction (PGD) is a leading cause of 30-day mortality following heart transplantation, and early intervention in PGD may correlate to improved survival. Our analysis aimed to determine the feasibility of measuring cardiac biomarkers from the donor heart in the early phase for use as a predictor of PGD.

METHODS

Blood samples from the coronary sinus were obtained at the time of transplantation in hearts preserved by cold static storage. The samples were analyzed for CK-MB and cTnI with a point-of-care method. The primary outcome was severe PGD or the need for veno-arterial extracorporeal membrane oxygenation within 7 days, referred to as severe graft dysfunction.

RESULTS

Of the total cohort (n = 63), eight patients (13%) were diagnosed with severe graft dysfunction within 7 days. Patients with high CK-MB had an increased risk for severe graft dysfunction with unadjusted Odds Ratio (OR) of 4.5 (95%CI .96-21.11 P = .057) and adjusted OR of 7.4 (95%CI 1.13-48.46, P = .037. Similar but non significant trends were observed for cTnI.

CONCLUSION

By measuring CK-MB from the coronary effluent in the donor heart, it may be possible to identify patients at increased risk for severe PGD after heart transplantation.

Identification of distinct secretory patterns and their regulatory networks of ischemia versus reperfusion phases in clinical heart transplantation

BACKGROUND

Ischemia/reperfusion injury (IRI) is associated with inflammatory responses contributing to the development of primary graft dysfunction (PGD) and rejection. Here, we investigated the pathophysiology of IRI and the early phase after heart transplantation (HTx) regarding its cytokine/chemokine and endothelial networks.

METHODS

Using multiplex technology, we assessed protein concentrations in plasma samples of HTx recipients (n = 11) pre-, postoperatively, 24 h and 3 weeks after HTx. The same proteins were quantified in organ storage solutions at the end of heart storage (n = 10). Unsupervised cluster, principal component analysis (PCA), K-nearest neighbor (KNN) network classifier analysis, ANOVA and Spearman correlation analyses were performed to identify specific patterns for IRI and individual kinetics of important soluble factors in HTx.

RESULTS

Unique patterns of soluble factors were identified in plasma of HTx patients. KNN analysis defined IL-10, IL-6, sIL-6Rα, IL-1RA, IL-16, sVEGFR-1, IGFBP-1, HGF and sHer-2 as strongest signals directly post-Tx declining 24 hrs after HTx. By contrast, MIF, osteopontin (OPN), sVCAM-1 and sICAM-1, IGFBP-1, SCGF-ß, HGF were highly enriched in organ storage solutions, reflecting distinct ischemic (storage solution) vs. reperfusion (plasma) signatures.

CONCLUSIONS

We identified specific inflammatory signatures for ischemic vs. reperfusion phases of HTx, associated with pro- as well as anti-inflammatory and endothelial biomarker candidates for IRI. These signatures might help to identify potential danger factors and their networks at both the ex situ (ischemic) as well as the reperfusion phase in the recipient after implantation.

Minimizing Ischemia Reperfusion Injury in Xenotransplantation

The recent dramatic advances in preventing "initial xenograft dysfunction" in pig-to-non-human primate heart transplantation achieved by minimizing ischemia suggests that ischemia reperfusion injury (IRI) plays an important role in cardiac xenotransplantation. Here we review the molecular, cellular, and immune mechanisms that characterize IRI and associated "primary graft dysfunction" in allotransplantation and consider how they correspond with "xeno-associated" injury mechanisms. Based on this analysis, we describe potential genetic modifications as well as novel technical strategies that may minimize IRI for heart and other organ xenografts and which could facilitate safe and effective clinical xenotransplantation.

Differential inflammatory responses of the native left and right ventricle associated with donor heart preservation

BACKGROUND

Dysfunction and inflammation of hearts subjected to cold ischemic preservation may differ between left and right ventricles, suggesting distinct strategies for amelioration.

METHODS AND RESULTS

Explanted murine hearts subjected to cold ischemia for 0, 4, or 8 h in preservation solution were assessed for function during 60 min of warm perfusion and then analyzed for cell death and inflammation by immunohistochemistry and western blotting and total RNA sequencing. Increased cold ischemic times led to greater left ventricle (LV) dysfunction compared to right ventricle (RV). The LV experienced greater cell death assessed by TUNEL+ cells and cleaved caspase-3 expression (n = 4). While IL-6 protein levels were upregulated in both LV and RV, IL-1β, TNFα, IL-10, and MyD88 were disproportionately increased in the LV. Inflammasome components (NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3), adaptor molecule apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1) and products (cleaved IL-1β and gasdermin D) were also more upregulated in the LV. Pathway analysis of RNA sequencing showed increased signaling related to tumor necrosis factor, interferon, and innate immunity with ex-vivo ischemia, but no significant differences were found between the LV and RV. Human donor hearts showed comparable inflammatory responses to cold ischemia with greater LV increases of TNFα, IL-10, and inflammasomes (n = 3).

CONCLUSIONS

Mouse hearts subjected to cold ischemia showed time-dependent contractile dysfunction and increased cell death, inflammatory cytokine expression and inflammasome expression that are greater in the LV than RV. However, IL-6 protein elevations and altered transcriptional profiles were similar in both ventricles. Similar changes are observed in human hearts.

Post-transplant inotrope score is associated with clinical outcomes after adult heart transplantation

BACKGROUND

Inotrope score has been proposed as a marker of clinical outcome after adult heart transplantation (HTx) but is rarely used in practice.

METHODS

Inotrope score during the first 48 h after HTx was calculated in 81 patients as: dopamine + dobutamine + amrinone + milrinone (dose × 15) + epinephrine (dose × 100) + norepinephrine (dose × 100) + enoximone + isoprenaline (dose × 100), with each drug in µg/kg/min. Determinants of inotrope score were identified with linear regression. Cox regression was used to determine the association of inotrope score with mortality.

RESULTS

The mean recipient age was 52 ± 11 years, and 32 (39.5%) patients were female. Determinants of inotrope score were preoperative C-reactive protein, serum urea, congenital heart disease, and donor cardiac arrest (R2  = .30). Inotrope score was associated with 5-year mortality, independent of recipient age and gender (HR 1.03, 95% CI 1.00-1.07). This association was attenuated when adjusting for female-to-male transplant and ischemia time. Inotrope score was also strongly associated with continuous veno-venous hemofiltration (OR 1.07, 95% CI 1.03-1.12).

CONCLUSION

High inotrope score post-HTx was observed in recipient congenital heart disease and was associated with a higher risk of mortality and acute kidney injury.

Veno-arterial Extracorporeal Membrane Oxygenation as Bridge to Heart Transplantation: The Way Forward

Advanced heart failure (HF) represents a public health priority due to the increase of affected patients and the meaningful mortality. Durable mechanical circulatory support (MCS) and heart transplantation (HTx) are unique therapies for end-stage HF (ESHF), with positive early and long-term outcomes. The patients who underwent HTx have a 1-y survival of 91% and a median survival of 12-13 y, whereas the median survival of ESHF is <12 mo. Short-term MCS with veno-arterial extracorporeal membrane oxygenation (VA ECMO) can be used as a bridge to transplantation strategy. Patients bridged with VA ECMO have significantly lower survival in comparison with non-MCS bridged and left ventricular assist device-bridged patients. VA ECMO represents an effective, and sometimes unique, system to obtain rapid hemodynamic stabilization, but possible negative effects on patients' outcomes after HTx must be considered. Here, we discuss the use of VA ECMO as bridge to transplantation.

Impact of increased donor distances following adult heart allocation system changes: A single center review of 1-year outcomes

BACKGROUND

On October 18, 2018, several changes to the donor heart allocation system were enacted. We hypothesize that patients undergoing orthotopic heart transplantation (OHT) under the new allocation system will see an increase in ischemic times, rates of primary graft dysfunction, and 1-year mortality due to these changes.

METHODS

In this single-center retrospective study, we reviewed the charts of all OHT patients from October 2017 through October 2019. Pre- and postallocation recipient demographics were compared. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

A total of 184 patients underwent OHT. Recipient demographics were similar between cohorts. The average distance from donor increased by more than 150 km (p = .006). Patients in the postallocation change cohort demonstrated a significant increase in the rate of severe left ventricle primary graft dysfunction from 5.4% to 18.7% (p = .005). There were no statistically significant differences in 30-day mortality or 1-year survival. Time on the waitlist was reduced from 203.8 to 103.7 days (p = .006).

CONCLUSIONS

Changes in heart allocation resulted in shorter waitlist times at the expense of longer donor distances and ischemic times, with an associated negative impact on early post-transplantation outcomes. No significant differences in 30-day or 1-year mortality were observed.

Blood Cardioplegia Induction, Perfusion Storage and Graft Dysfunction in Cardiac Xenotransplantation

Background

Perioperative cardiac xenograft dysfunction (PCXD) describes a rapidly developing loss of cardiac function after xenotransplantation. PCXD occurs despite genetic modifications to increase compatibility of the heart. We report on the incidence of PCXD using static preservation in ice slush following crystalloid or blood-based cardioplegia versus continuous cold perfusion with XVIVO^© heart solution (XHS) based cardioplegia.

Methods

Baboons were weight matched to genetically engineered swine heart donors. Cardioplegia volume was 30 cc/kg by donor weight, with del Nido cardioplegia and the addition of 25% by volume of donor whole blood. Continuous perfusion was performed using an XVIVO ^© Perfusion system with XHS to which baboon RBCs were added.

Results

PCXD was observed in 5/8 that were preserved with crystalloid cardioplegia followed by traditional cold, static storage on ice. By comparison, when blood cardioplegia was used followed by cold, static storage, PCXD occurred in 1/3 hearts and only in 1/5 hearts that were induced with XHS blood cardioplegia followed by continuous perfusion. Survival averaged 17 hours in those with traditional preservation and storage, followed by 11.47 days and 15.03 days using blood cardioplegia and XHS+continuous preservation, respectively. Traditional preservation resulted in more inotropic support and higher average peak serum lactate 14.3±1.7 mmol/L compared to blood cardioplegia 3.6±3.0 mmol/L and continuous perfusion 3.5±1.5 mmol/L.

Conclusion

Blood cardioplegia induction, alone or followed by XHS perfusion storage, reduced the incidence of PCXD and improved graft function and survival, relative to traditional crystalloid cardioplegia-slush storage alone.

Long-term outcomes of patients with primary graft dysfunction after cardiac transplantation

OBJECTIVES

The International Society of Heart and Lung Transplantation (ISHLT) criteria for primary graft dysfunction (PGD) after cardiac transplantation have been shown to stratify patient outcomes up to 1 year after transplantation, but scarce data are available regarding outcomes beyond the 1st year. We sought to characterize survival of patients with PGD following cardiac transplantation beyond the 1st year.

METHODS

A retrospective review of consecutive patients undergoing isolated cardiac transplantation at a single centre between 2012 and 2015 was performed. Patients were diagnosed with none, mild, moderate or severe PGD by the ISHLT criteria. Survival was ascertained from the United Network for Organ Sharing database and chart review. Kaplan-Meier curves were plotted to compare survival. The hazard ratio for mortality associated with PGD severity was estimated using Cox-proportional hazards modelling, with a pre-specified conditional survival analysis at 90 days.

RESULTS

A total of 257 consecutive patients underwent cardiac transplantation during the study period, of whom 73 (28%) met ISHLT criteria for PGD: 43 (17%) mild, 12 (5%) moderate and 18 (7%) severe. Patients with moderate or severe PGD had decreased survival up to 5 years after transplantation (log-rank P < 0.001). Landmark analyses demonstrated that patients with moderate or severe PGD were at increased risk of mortality during the first 90-days after transplantation as compared to those with none or mild PGD [hazard ratio (95% confidence interval) 18.9 (7.1-50.5); P < 0.001], but this hazard did not persist beyond 90-days in survivors (P = 0.64).

CONCLUSIONS

A diagnosis of moderate or severe PGD is associated with increased mortality up to 5 years after cardiac transplantation. However, patients with moderate or severe PGD who survive to post-transplantation day 90 are no longer at increased risk for mortality as compared to those with none or mild PGD.