Cardiac Transplantation

Impact of Left Ventricular-Vascular Interaction on Long-Term Outcome After Heart Transplantation

BACKGROUND AND AIM

To compare pressure-volume (PV) derivative variables between HT patients and healthy controls and to assess their impact on long-term outcome.

METHODS

In this single-center retrospective study, HT patients surviving their first post-HT year with left ventricular ejection fraction (LVEF) ≥50%, absence of allograft vasculopathy, and rejection were enrolled. PV variable surrogates were measured by transthoracic echocardiography and compared with healthy controls. The endpoint was cardiovascular mortality.

RESULTS

From 1985 to 2015, 345 patients were enrolled. Arterial elastance (Ea) and left ventricular end-systolic elastance (Ees) were higher in HT recipients than in healthy controls (4.03 vs. 1.65, p < 0.0001 and 6.75 vs. 2.47, p < 0.0001, respectively), while ventricular arterial coupling (VAC) was similar between the two groups (0.66 vs. 0.59, p = 0.105). After a median of 11.3-year follow-up, 59 (17%) HT recipients died. VAC was not significantly associated with cardiac mortality (p = 0.074). Survival was lower in HT recipients with Ea > 4 mmHg/mL/m2 and Ees ≤ 6.75 mmHg/mL/m2, and both were independently associated with mortality risk after adjustment (Ea > 4 mmHg/mL/m2: HR 2.25 [95% CI 1.38-3.66], p = 0.013; Ees ≤ 6.75 mmHg/mL/m2: HR 3.70 [95% CI 1.95-7.06], p = 0.001).

CONCLUSIONS

In HT recipients surviving the first year after transplantation with normal LVEF, high Ea, and low Ees values were independently associated with poorer outcomes in long-term follow-up.

Goodnight Moon: The (not so) mystical effect of folklore and superstitions on cardiac transplantation

BACKGROUND

The effect of Friday the 13th and Full Moons on cardiac transplantation is unknown. We investigated the impact of these superstitious events on recipient and donor qualities, complications, survival, and volume.

METHODS

All adult transplants from 2013-2023 in the United Network for Organ Sharing database were retrospectively reviewed. Friday the 13th recipients were compared to Adjacent Friday recipients and all other recipients. Full Moon recipients were compared to New Moon recipients and all other transplants. Recipient and donor characteristics were statistically compared, and outcomes including transplant volume, frequency, complications, and survival were assessed between groups before, and after, the 2018 allocation change.

RESULTS

One thousand and twenty transplants occurred on a Full Moon, and 134 occurred on a Friday the 13th. No differences between donors, recipients, or outcomes and volume across eras were found in the Lunar analysis (all p > 0.05). Compared to Adjacent Friday recipients, but not to the control group, Friday the 13th recipients had higher rates of severe functional impairment (44% vs 41%), longer admissions before transplant (4 vs 1 day), and a higher prevalence of intensive care unit placement (40% vs 35%) (all p < 0.05). However, no differences were found in donor characteristics, outcomes, survival, or volume in either era (all p > 0.05).

CONCLUSIONS

There is likely no substantial adverse or unlucky influence of the Full Moon or Friday the 13th on cardiac transplantation. However, perceived stress has demonstrated effects on medical outcomes and health system functioning. Therefore, further research should investigate the persistence of these beliefs in health care settings.

Silk-based biomaterials for tissue engineering

Tissue engineering (TE) involves repairing, replacing, regeneration, or improving the function of tissues and organs by combining cells, growth factors and scaffold materials. Among these, scaffold materials play a crucial role. Silk fibroin (SF), a natural biopolymer, has been widely used in the TE field due to its good biodegradability, biocompatibility, and mechanical properties attributed to its chemical composition and structure. This paper reviews the structure, extraction, and modification methods of SF. In addition, it discusses SF's regulation of cell behavior and its various processing modes. Finally, the applications of SF in TE and perspectives on future developments are presented. This review provides comprehensive and alternative rational insights for further biomedical translation in SF medical device design, further revealing the great potential of SF biomaterials.

Impact of Heart Transplant Allocation Changes on Waitlist Mortality and Clinical Practice in Pediatric and Adult Patients With Congenital Heart Disease and Cardiomyopathy

BACKGROUND

The United Network of Organ Sharing made changes to the priority for allocation of hearts for transplantation in 2016 for pediatric patients and 2018 for adult patients. Although recent work has evaluated the impact of the revised allocation systems on mechanical circulatory support practices and waitlist outcomes, there are limited data that focus more specifically on the impact of the allocation changes on patients with congenital heart disease (CHD) or cardiomyopathy and how these relationships might differ in pediatric and adult patients.

METHODS

The United Network of Organ Sharing database was queried for pediatric (<18 years of age) and adult (18-50 years of age) patients with a CHD or cardiomyopathy diagnosis listed for heart transplantation. Cohorts were grouped into preallocation and postallocation change eras: pediatric patients from January 1, 2011, to March 21, 2016, and January 1, 2017, to December 31, 2021; and adult patients from January 1, 2015, to October 17, 2018, and January 1, 2019, to December 31, 2021. Differences in era for survival or waitlist removal because of clinical deterioration from the time of heart transplantation listing were compared using competing risk models.

RESULTS

We identified 11 637 patients listed for heart transplantation during the study period, including 2882 pediatric patients with CHD, 594 adults with CHD, 2348 pediatric patients with cardiomyopathy, and 5813 adults with cardiomyopathy. In a competing risk model adjusting for demographic and clinical factors, allocation changes were significantly associated with lower death or waitlist removal within 1 year of heart transplantation listing in infants with CHD (hazard ratio, 0.75 [95% CI, 0.57-0.99]; P=0.04), children with CHD (hazard ratio, 0.61 [95% CI, 0.43-0.86]; P=0.005), and adults with cardiomyopathy (hazard ratio, 0.60 [95% CI, 0.44-0.81]; P=0.001), but not in infants with cardiomyopathy, children with cardiomyopathy, or adults with CHD.

CONCLUSIONS

The recent allocation changes of the Organ Procurement and Transplantation Network associations with waitlist duration and outcome were not uniform across pediatric and adult cohorts with CHD or those with cardiomyopathy. Children with cardiomyopathy and adults with CHD did not experience the mortality benefits experienced by adults with cardiomyopathy and children with CHD. Future iterations of the allocation systems should consider differential access to mechanical circulatory support options for children and adults, patient sensitization status, and whether having separate systems for adults and children is the most appropriate method to allocate organs.

The effect of proteasome in heart transplantation: From mechanisms to therapeutic potential

Heart transplantation is a critical treatment for end-stage heart failure. However, its clinical efficacy is hindered by some challenges, such as ischemia-reperfusion injury (IRI) and post-transplant rejection. These complications significantly contribute to graft dysfunction and compromise patient survival. Emerging evidence underscores the involvement of proteasome in the pathophysiology of both IRI and post-transplant rejection. Proteasome inhibition has demonstrated potential in attenuating IRI by limiting oxidative damage and apoptosis while also mitigating rejection through the regulation of adaptive and innate immune responses. Recent advances in the development of proteasome inhibitors, particularly in optimizing specificity and minimizing adverse effects, have further strengthened their prospects for clinical application. This review focuses on the roles of the proteasome and its inhibitors in heart transplantation, with an emphasis on their mechanisms and therapeutic applications in managing IRI and rejection.

Intervening to Preserve Function in Ischemic Cardiomyopathy with a Porous Hydrogel and Extracellular Matrix Composite in a Rat Myocardial Infarction Model

Multiple hydrogels are developed for injection therapy after myocardial infarction, with some incorporating substances promoting tissue regeneration and others emphasizing mechanical effects. In this study, porosity and extracellular matrix-derived digest (ECM) are incorporated, into a mechanically optimized, thermoresponsive, degradable hydrogel (poly(N-isopropylacrylamide-co-N-vinylpyrrolidone-co-MAPLA)) and evaluate whether this biomaterial injectate can abrogate adverse remodeling in rat ischemic cardiomyopathy. After myocardial infarction, rats are divided into four groups: NP (non-porous hydrogel) without either ECM or porosity, PM (porous hydrogel) from the same synthetic copolymer with mannitol beads as porogens, and PME with porosity and ECM digest added to the synthetic copolymer. PBS injection alone is a control group. Intramyocardial injections occurred 3 days after myocardial infarction followed by serial echocardiography and histological assessments 8 weeks after infarction. Echocardiographic function and neovascularization improved in the PME group compared to the other hydrogels and PBS injection. The PME group also demonstrated improved LV geometry and macrophage polarization (toward M2) compared to PBS, whereas differences are not observed in the NP or PM groups versus control. These results demonstrate further functional improvement may be achieved in hydrogel injection therapy for ischemic cardiomyopathy by incorporating porosity and ECM digest, representing combined mechanical and biological effects.

Drug-Loaded Mesoporous Polydopamine Nanoparticles in Chitosan Hydrogels Enable Myocardial Infarction Repair through ROS Scavenging and Inhibition of Apoptosis

In this study, we synthesized mesoporous polydopamine nanoparticles (MPDA NPs) using an emulsion-induced interface assembly strategy and loaded epigallocatechin gallate (EGCG) into MPDA NPs via electrostatic attraction to form EGCG@MPDA NPs. In the post myocardial infarction (MI) environment, these interventions specifically aimed to eliminate reactive oxygen species (ROS) and facilitate the repair of MI. We further combined them with a thermosensitive chitosan (CS) hydrogel to construct an injectable composite hydrogel (EGCG@MPDA/CS hydrogel). Utilizing in vitro experiments, the EGCG@MPDA/CS hydrogel exhibited excellent ROS-scavenging ability of H9C2 cells under the oxidative stress environment and also could inhibit their apoptosis. The EGCG@MPDA/CS hydrogel significantly promoted left ventricular ejection fraction (LVEF) in infarcted rat models post injection for 28 days compared to the PBS group (51.25 ± 1.73% vs 29.31 ± 0.78%, P < 0.05). In comparison to the PBS group, histological analysis revealed a substantial increase in left ventricular (LV) wall thickness in the EGCG@MPDA/CS hydrogel group (from 0.58 ± 0.03 to 1.39 ± 1.11 mm, P < 0.05). This work presents a novel approach to enhance MI repair by employing the EGCG@MPDA/CS hydrogel. This hydrogel effectively reduces local oxidative stress by ROS and stimulates the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway.

Advancing Cardiac Care: A Registry of Heart Transplantation in Latin America (1968-2022)

INTRODUCTION

Heart transplantation (HTx) has emerged as a pivotal intervention for end-stage heart failure, offering significant improvements in survival and quality of life. This manuscript elucidates the landscape of HTx across Latin America (LATAM) from its advent in 1968 through December 2022, shedding light on its evolution, current practices, and regional disparities.

METHODS

We distributed a structured questionnaire to the national coordinators or representatives of the Interamerican Council of Heart Failure and Pulmonary Hypertension, collating responses from 20 LATAM nations. This approach facilitated a comprehensive aggregation of regional HTx data.

RESULTS

A total of 12,374 HTx were performed in 166 centers across 16 LATAM countries, with Brazil, Argentina, and Colombia accounting for the majority of procedures. Pediatric transplants represented 9% of the total caseload, and combined organ transplants were reported in 62.5% of the participating countries, underscoring the complexity and breadth of transplant services in the region.

CONCLUSION

Despite facing infrastructural and logistical challenges, LATAM has demonstrated a robust capacity to conduct high-complexity transplant procedures. The establishment of a structured, regional HTx registry is imperative to enhance data collection and analysis, which in turn can inform clinical decision-making and policy development, ultimately improving patient outcomes across the continent.

Donation After Circulatory Death Heart Transplant: Current State and Future Directions

Orthotopic heart transplant is the gold standard therapeutic intervention for patients with end-stage heart failure. Conventionally, heart transplant has relied on donation after brain death for organ recovery. Donation after circulatory death (DCD) is the donation of the heart after confirming that circulatory function has irreversibly ceased. DCD-orthotopic heart transplant differs from donation after brain death-orthotopic heart transplant in ways that carry implications for widespread adoption, including differences in organ recovery, storage and ethical considerations surrounding normothermic regional perfusion with DCD. Despite these differences, DCD has shown promising early outcomes, augmenting the donor pool and allowing more individuals to benefit from orthotopic heart transplant. This review aims to present the current state and future trajectory of DCD-heart transplant, examine key differences between DCD and donation after brain death, including clinical experiences and innovations in methodologies, and address the ongoing ethical challenges surrounding the new frontier in heart transplant with DCD donors.

Impact of Age of Heart Transplant Program on Patient Survival and Post-Transplant Outcomes

BACKGROUND

The relationship between age of a heart transplant (HT) program and outcomes has not been explored.

METHODS

We performed a retrospective cohort analysis of the United Network for Organ Sharing database of all adult HTs between 2009 and 2019. For each patient, we created a variable that corresponded to program age: new (<5), developing (≥5 but <10) and established (≥10) years.

RESULTS

Of 20 997 HTs, 822 were at new, 908 at developing, and 19 267 at established programs. Patients at new programs were significantly more likely to have history of cigarette smoking, ischemic cardiomyopathy, and prior sternotomy. These programs were less likely to accept organs from older donors and those with a history of hypertension or cigarette use. As compared to patients at new programs, transplant patients at established programs had less frequent rates of treated rejection during the index hospitalization (HR 0.43 [95% CI, 0.36-0.53] p < 0.001) and at 1 year (HR 0.58 [95% CI, 0.49-0.70], p < 0.001), less frequently required pacemaker implantations (HR 0.50 [95% CI, 0.36-0.69], p < 0.001), and less frequently required dialysis (HR 0.66 [95% CI, 0.53-0.82], p < 0.001). However, there were no significant differences in short- or long-term survival between the groups (log-rank p = 0.24).

CONCLUSION

Patient and donor selection differed between new, developing, and established HT programs but had equivalent survival. New programs had increased likelihood of treated rejection, pacemaker implantation, and need for dialysis. Standardized post-transplant practices may help to minimize this variation and ensure optimal outcomes for all patients.

Variation in risk-adjusted cardiac intensive care unit (CICU) length of stay and the association with in-hospital mortality: An analysis from the Critical Care Cardiology Trials Network (CCCTN) registry

BACKGROUND

Previous studies have suggested that there is wide variability in cardiac intensive care unit (CICU) length of stay (LOS); however, these studies are limited by the absence of detailed risk assessment at the time of admission. Thus, we evaluated inter-hospital differences in CICU LOS, and the association between LOS and in-hospital mortality.

METHODS

Using data from the Critical Care Cardiology Trials Network (CCCTN) registry, we included 22,862 admissions between 2017 and 2022 from 35 primarily tertiary and quaternary CICUs that captured consecutive admissions in annual 2-month snapshots. The primary analysis compared inter-hospital differences in CICU LOS, as well as the association between CICU LOS and all-cause in-hospital mortality using a Fine and Gray competing risk model.

RESULTS

The overall median CICU LOS was 2.2 (1.1-4.8) days, and the median hospital LOS was 5.9 (2.8-12.3) days. Admissions in the longest tertile of LOS tended to be younger with higher rates of pre-existing comorbidities, and had higher Sequential Organ Failure Assessment (SOFA) scores, as well as higher rates of mechanical ventilation, intravenous vasopressor use, mechanical circulatory support, and renal replacement therapy. Unadjusted all-cause in-hospital mortality was 9.3%, 6.7%, and 13.4% in the lowest, intermediate, and highest CICU LOS tertiles. In a competing risk analysis, individual patient CICU LOS was correlated (r2 = 0.31) with a higher risk of 30-day in-hospital mortality. The relationship remained significant in admissions with heart failure, ST-elevation myocardial infarction and non-ST segment elevation myocardial infarction.

CONCLUSIONS

In a large registry of academic CICUs, we observed significant variation in CICU LOS and report that LOS is independently associated with all-cause in-hospital mortality. These findings could potentially be used to improve CICU resource utilization planning and refine risk prognostication in critically ill cardiovascular patients.

A cigarette filter-derived biomimetic cardiac niche for myocardial infarction repair

Cell implantation offers an appealing avenue for heart repair after myocardial infarction (MI). Nevertheless, the implanted cells are subjected to the aberrant myocardial niche, which inhibits cell survival and maturation, posing significant challenges to the ultimate therapeutic outcome. The functional cardiac patches (CPs) have been proved to construct an elastic conductive, antioxidative, and angiogenic microenvironment for rectifying the aberrant microenvironment of the infarcted myocardium. More importantly, inducing implanted cardiomyocytes (CMs) adapted to the anisotropic arrangement of myocardial tissue by bioengineered structural cues within CPs are more conducive to MI repair. Herein, a functional Cig/(TA-Cu) CP served as biomimetic cardiac niche was fabricated based on structural anisotropic cigarette filter by modifying with tannic acid (TA)-chelated Cu2+ (TA-Cu complex) via a green method. This CP possessed microstructural anisotropy, electrical conductivity and mechanical properties similar to natural myocardium, which could promote elongation, orientation, maturation, and functionalization of CMs. Besides, the Cig/(TA-Cu) CP could efficiently scavenge reactive oxygen species, reduce CM apoptosis, ultimately facilitating myocardial electrical integration, promoting vascular regeneration and improving cardiac function. Together, our study introduces a functional CP that integrates multimodal cues to create a biomimetic cardiac niche and provides an effective strategy for cardiac repair.

Hydrogels for the Treatment of Myocardial Infarction: Design and Therapeutic Strategies

Cardiovascular diseases (CVDs) have become the leading global burden of diseases in recent years and are the primary cause of human mortality and loss of healthy life expectancy. Myocardial infarction (MI) is the top cause of CVDs-related deaths, and its incidence is increasing worldwide every year. Recently, hydrogels have garnered great interest from researchers as a promising therapeutic option for cardiac tissue repair after MI. This is due to their excellent properties, including biocompatibility, mechanical properties, injectable properties, anti-inflammatory properties, antioxidant properties, angiogenic properties, and conductive properties. This review discusses the advantages of hydrogels as a novel treatment for cardiac tissue repair after MI. The design strategies of various hydrogels in MI treatment are then summarized, and the latest research progress in the field is classified. Finally, the future perspectives of this booming field are also discussed at the end of this review.

Heart transplantation: advances in expanding the donor pool and xenotransplantation

Approximately 65 million adults globally have heart failure, and the prevalence is expected to increase substantially with ageing populations. Despite advances in pharmacological and device therapy of heart failure, long-term morbidity and mortality remain high. Many patients progress to advanced heart failure and develop persistently severe symptoms. Heart transplantation remains the gold-standard therapy to improve the quality of life, functional status and survival of these patients. However, there is a large imbalance between the supply of organs and the demand for heart transplants. Therefore, expanding the donor pool is essential to reduce mortality while on the waiting list and improve clinical outcomes in this patient population. A shift has occurred to consider the use of organs from donors with hepatitis C virus, HIV or SARS-CoV-2 infection. Other advances in this field have also expanded the donor pool, including opt-out donation policies, organ donation after circulatory death and xenotransplantation. We provide a comprehensive overview of these various novel strategies, provide objective data on their safety and efficacy, and discuss some of the unresolved issues and controversies of each approach.

Donor Age, Sex, and Cause of Death and Their Relationship to Heart Transplant Recipient Cardiac Death

BACKGROUND

Recent studies indicate that donor innate immune responses participate in initiating and accelerating innate responses and allorecognition in the recipient. These immune responses negatively affect recipient outcomes and predispose recipients to cardiovascular death (CV death). We hypothesized that a donor cause of death (COD) associated with higher levels of innate immune response would predispose recipients to more adverse outcomes post-transplant, including CV death.

METHODS

We performed a single-institution retrospective analysis comparing donor characteristics and COD to recipient adverse cardiovascular outcomes. We analyzed the medical records of local adult donors (age 18-64) in a database of donors where adequate data was available. Donor age was available on 706 donors; donor sex was available on 730 donors. We linked donor characteristics (age and sex) and COD to recipient CV death. The data were analyzed using logistic regression, the log-rank test of differences, and Tukey contrast.

RESULTS

Donor age, female sex, and COD of intracranial hemorrhage were significantly associated with a higher incidence of recipient CV death.

CONCLUSIONS

In this single institution study, we found that recipients with hearts from donors over 40 years, donors who were female, or donors who died with a COD of intracranial hemorrhage had a higher frequency of CV death. Donor monitoring and potential treatment of innate immune activation may decrease subsequent recipient innate responses and allorecognition stimulated by donor-derived inflammatory signaling, which leads to adverse outcomes.

Therapeutic potential role of vitamin C in prevention and control of heart transplant rejection and cardiac allograft vasculopathy. A need for consideration

The burden of cardiovascular diseases is rising rapidly globally. Heart transplant is one of the most last resort medical option for patients with heart failure. Unfortunately, this surgical intervention is associated with several serious complications including heart transplant rejection (HTR) and Cardiac Allograft Vasculopathy (CAV) which can manifest just within few years' posttransplant. These complications affect significantly the prognosis and quality of life among postheart transplant patients. Several medications including immunosuppressant, antibiotics, antihypertensive, and statins have been used during posttransplant care so as to address such complications. Unfortunately, most of those drugs are expensive and pose a number of serious side effects to the patients enough to compromise patients' quality of life too. Several studies on Vitamin C are therapeutically suggestive that it can be used during postheart transplant care with more cost-effective benefits with less and minimized side effects compared to the current drugs in place. It should be considered pharmacologically that Vitamin C has a great potential role clinically in prevention and control of HTR and CAV development. On the light of such findings as described above, we recommend more studies especially clinical trials and molecular studies to determine whether Vitamin C can be repositioned to replace or to be used along the current drug regimens used in postheart transplant care for prevention and control of HTR and CAV.

Impact of Donor Hemodynamics on Recipient Survival in Heart Transplantation

BACKGROUND

Heart transplantation is the gold-standard therapy for end-stage heart failure, but rates of donor-heart use remain low due to various factors that are often not evidence based. The impact of donor hemodynamics obtained via right-heart catheterization on recipient survival remains unclear.

METHODS

The United Network for Organ Sharing registry was used to identify donors and recipients from September 1999-December 2019. Donor hemodynamics data were obtained and analyzed using univariate and multivariable logistical regression, with the primary endpoints being 1- and 5-year post-transplant survival.

RESULTS

Of the 85,333 donors who consented to heart transplantation during the study period, 6573 (7.7%) underwent right-heart catheterization, of whom 5531 eventually underwent procurement and transplantation. Donors were more likely to undergo right-heart catheterization if they had high-risk criteria. Recipients who had donor hemodynamic assessment had 1- and 5-year survival rates similar to those without donor hemodynamic assessment (87% vs 86%, 1 year). Abnormal hemodynamics were common in donor hearts but did not impact recipient survival rates, even when risk-adjusted in multivariable analysis.

CONCLUSIONS

Donors with abnormal hemodynamics may represent an opportunity to expand the pool of viable donor hearts.

Advanced heart failure: a contemporary approach

Advanced heart failure (HF) is defined as the persistence of severe symptoms despite the use of optimized medical, surgical, and device therapies. These patients require timely advanced treatments, such as heart transplantation or long-term mechanical circulatory support (MCS). Inotropic agents are often used to reduce congestion and increase cardiac output, while renal replacement therapy may be beneficial if necessary. Cardiac resynchronization therapy has clear benefits in patients with HF with reduced ejection fraction, particularly with left bundle branch block (QRS duration > 130 ms). The role of implantable cardioverter-defibrillators in advanced HF patients requires further investigation considering the introduction of novel HF medications. In selected patients with significant secondary mitral regurgitation, transcatheter edge-to-edge repair can help delay heart transplantation or long-term MCS. In later stages, the appropriateness of heart transplantation should be evaluated, and the use of short- or long-term MCS may be considered. A multidisciplinary HF management program is crucial for patients with advanced HF. Recent treatment advances, including drugs, devices, and MCS, have broadened the options available to patients with advanced HF and this trend is expected to continue.

Multimodal Prehabilitation in Heart Transplant Recipients Improves Short-Term Post-Transplant Outcomes without Increasing Costs

(1) Background and aim: This study aimed to investigate the impact of prehabilitation on the postoperative outcomes of heart transplantation and its cost-effectiveness. (2) Methods: This single-center, ambispective cohort study included forty-six candidates for elective heart transplantation from 2017 to 2021 attending a multimodal prehabilitation program consisting of supervised exercise training, physical activity promotion, nutritional optimization, and psychological support. The postoperative course was compared to a control cohort consisting of patients transplanted from 2014 to 2017 and those contemporaneously not involved in prehabilitation. (3) Results: A significant improvement was observed in preoperative functional capacity (endurance time 281 vs. 728 s, p < 0.001) and quality-of-life (Minnesota score 58 vs. 47, p = 0.046) after the program. No exercise-related events were registered. The prehabilitation cohort showed a lower rate and severity of postoperative complications (comprehensive complication index 37 vs. 31, p = 0.033), lower mechanical ventilation time (37 vs. 20 h, p = 0.032), ICU stay (7 vs. 5 days, p = 0.01), total hospitalization stay (23 vs. 18 days, p = 0.008) and less need for transfer to nursing/rehabilitation facilities after hospital discharge (31% vs. 3%, p = 0.009). A cost-consequence analysis showed that prehabilitation did not increase the total surgical process costs. (4) Conclusions: Multimodal prehabilitation before heart transplantation has benefits on short-term postoperative outcomes potentially attributable to enhancement of physical status, without cost-increasing.

Chronotropic Incompetence after Heart Transplantation Is Associated with Increased Mortality and Decreased Functional Capacity

INTRODUCTION

The contribution of chronotropic incompetence to reduced exercise tolerance after a heart transplant is well known, but its role as a prognostic marker of post-transplant mortality is unclear. The aim of this study is to examine the relationship between post-transplant heart rate response (HRR) and survival.

METHODS

We performed a retrospective analysis of all adult heart transplant recipients at the University of Pennsylvania between the years 2000 and 2011 who underwent a cardiopulmonary exercise test (CPET) within a year of transplant. Follow-up time and survival status were observed through October 2019, using data merged from the Penn Transplant Institute. HRR was calculated by subtracting the resting HR from the peak exercise HR. The association between HRR and mortality was analyzed using Cox proportional hazard models and Kaplan-Meier analysis. The optimal cut-off point for HRR was generated by Harrell's C statistic. Patients with submaximal exercise tests were excluded, defined by a respiratory exchange ratio (RER) cut-off of 1.05.

RESULTS

Of 277 patients with CPETs performed within a year post-transplant, 67 were excluded for submaximal exercise. In the 210 included patients, the mean follow-up time was 10.9 years (Interquartile range (IQR) 7.8-14). Resting HR and peak HR did not significantly impact mortality after adjusting for covariates. In a multivariable linear regression analysis, each 10-beat increase in heart rate response was associated with a 1.3 mL/kg/min increase in peak V_O2 and a 48 s increase in the total exercise time. Each beat/min increase in HRR was associated with a 3% reduction in the hazard of mortality (HR 0.97; 95% CI 0.96-0.99, p = 0.002). Using the optimal cut-off point generated by Harrell's C statistic, survival was significantly higher in patients with an HRR > 35 beats/min compared to those with an HRR < 35 beats/min (log rank p = 0.0012).

CONCLUSION

In heart transplant patients, a low HRR is associated with increased all-cause mortality and decreased exercise capacity. Additional studies are needed to validate whether targeting HRR in cardiac rehabilitation may improve outcomes.

The impact of postoperative cognitive impairment on mid-term survival after heart transplantation

BACKGROUND

Heart transplantation is the definitive therapy for patients with end-stage heart failure. Antecedent studies reported that a substantial proportion of heart transplant recipients developed postoperative cognitive impairment in the long term. However, no studies have explored the association between postoperative cognitive impairment and survival after heart transplantation.

METHODS

The data of 43 adult patients who underwent heart transplantation were consecutively enrolled and assessed using the MMSE and MoCA neuropsychological tests. Kaplan-Meier curves and Cox proportional hazards models were used for survival analyses. Primary component analysis was performed to integrate MoCA subtests into the "Attention factor," "Naming factor," and "Orientation factor."

RESULTS

About 30% of the patients were diagnosed with short-term postoperative cognitive impairment. The impairment group was older and had lower baseline cognitive performances, larger LV diameter, worse MMSE decline and higher ratio of significant MoCA decline. Postoperative cognitive impairment was significantly associated with worse survival (P = .028). Multivariate Cox analyses showed that higher postoperative MoCA score was significantly associated with lower mid-term post-transplant mortality (HR = .744 [.584, .949], P = .017), in which "Attention factor" contributed to this association most (HR = .345 [.123, .970], P = .044) rather than "Naming factor" or "Orientation factor." Notably, preoperative cognitive impairment was closely related with postoperative cognitive impairment and also indicated the worse post-transplant survival (P = .015).

CONCLUSION

Postoperative as well as preoperative cognitive impairments were associated with a worse mid-term survival after heart transplantation, indicating that neuropsychological assessments before and after heart transplantation should be routinely performed for heart transplant recipients for better risk stratification.

Impact of Temporary Preoperative Mechanical Support on Heart Transplant Outcomes

We sought to assess the impact of temporary preoperative mechanical circulatory support (TPMCS) on heart transplantation outcomes. A total of 4,060 adult heart transplants from June 1, 2006, to December 31, 2019, were identified in the Scientific Registry of Transplant Recipients database as having TPMCS. Recipients were divided into groups based on their type of TPMCS: intra-aortic balloon pump (IABP), temporary ventricular assist device (VAD), biventricular assist device (BIVAD), and extracorporeal membrane oxygenation (ECMO). Perioperative outcomes and survival were compared among groups. Recipients with IABP were associated with older age, a smoking history, and a significantly shorter wait list time ( p < 0.01). Recipients with ECMO had a significantly increased in-hospital mortality as well as an increased incidence of dialysis ( p < 0.01). Kaplan-Meier analysis revealed worse 1 and 5 year survival for recipients with ECMO. Cox model demonstrated a significantly increased risk of mortality with BIVAD (hazard ratio [HR], 1.33; 95% CI, 1.12-1.57; p < 0.01) and ECMO (HR, 1.64; 95% CI, 1.33-2.03; p < 0.01). While patients with IABP have a survival comparable to patients without TPMCS or durable left VAD, outcomes for BIVADs and ECMO are not as favorable. Transplantation centers must continue to make careful choices about the type of TPMCS utilized before heart transplant.

Cardiac xenotransplantation: from concept to clinic

For many patients with terminal/advanced cardiac failure, heart transplantation is the most effective, durable treatment option, and offers the best prospects for a high quality of life. The number of potentially life-saving donated human organs is far fewer than the population who could benefit from a new heart, resulting in increasing numbers of patients awaiting replacement of their failing heart, high waitlist mortality, and frequent reliance on interim mechanical support for many of those deemed among the best candidates but who are deteriorating as they wait. Currently, mechanical assist devices supporting left ventricular or biventricular heart function are the only alternative to heart transplant that is in clinical use. Unfortunately, the complication rate with mechanical assistance remains high despite advances in device design and patient selection and management, and the quality of life of the patients even with good outcomes is only moderately improved. Cardiac xenotransplantation from genetically multi-modified (GM) organ-source pigs is an emerging new option as demonstrated by the consistent long-term success of heterotopic (non-life-supporting) abdominal and life-supporting orthotopic porcine heart transplantation in baboons, and by a recent 'compassionate use' transplant of the heart from a GM pig with 10 modifications into a terminally ill patient who survived for 2 months. In this review, we discuss pig heart xenotransplantation as a concept, including pathobiological aspects related to immune rejection, coagulation dysregulation, and detrimental overgrowth of the heart, as well as GM strategies in pigs to prevent or minimize these problems. Additional topics discussed include relevant results of heterotopic and orthotopic heart transplantation experiments in the pig-to-baboon model, microbiological and virologic safety concepts, and efficacy requirements for initiating formal clinical trials. An adequate regulatory and ethical framework as well as stringent criteria for the selection of patients will be critical for the safe clinical development of cardiac xenotransplantation, which we expect will be clinically tested during the next few years.

Reevaluating the Ethical Issues in Porcine-to-Human Heart Xenotransplantation

A major limiting factor with heart allotransplantation remains the availability of organs from deceased donors. Porcine heart xenotransplantation could serve as an alternative source of organs for patients with terminal heart failure. A first-in-human porcine xenotransplantation that occurred in January 2022 at the University of Maryland Medical Center provided an opportunity to examine several ethical issues to guide selection criteria for future xenotransplantation clinical trials. In this article, the authors, who are clinicians at UMMC, discuss the appropriate balancing of risks and benefits and the significance, if any, of clinical equipoise. The authors also review the alleged role of the psychosocial evaluation in identifying patients at an elevated risk of posttransplant noncompliance, and they consider how the evaluation's implementation might enhance inequities among diverse populations. The authors argue that, based on the principle of reciprocity, psychosocial criteria should be used, not to exclude patients, but instead to identify patients who need additional support. Finally, the authors discuss the requirements for and the proper assessment of informed and voluntary consent from patients being considered for xenotransplantation.

Primary Graft Dysfunction after Heart Transplantation - Unravelling the Enigma

Primary graft dysfunction (PGD) remains the main cause of early mortality following heart transplantation despite several advances in donor preservation techniques and therapeutic strategies for PGD. With that aim of establishing the aetiopathogenesis of PGD and the preferred management strategies, the new consensus definition has paved the way for multiple contemporaneous studies to be undertaken and accurately compared. This review aims to provide a broad-based understanding of the pathophysiology, clinical presentation and management of PGD.

Recent Advances in Designing Electroconductive Biomaterials for Cardiac Tissue Engineering

Implantable cardiac patches and injectable hydrogels are among the most promising therapies for cardiac tissue regeneration following myocardial infarction. Incorporating electrical conductivity into these patches and hydrogels is found to be an efficient method to improve cardiac tissue function. Conductive nanomaterials such as carbon nanotube, graphene oxide, gold nanorod, as well as conductive polymers such as polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate are appealing because they possess the electroconductive properties of semiconductors with ease of processing and have potential to restore electrical signaling propagation through the infarct area. Numerous studies have utilized these materials for regeneration of biological tissues that possess electrical activities, such as cardiac tissue. In this review, recent studies on the use of electroconductive materials for cardiac tissue engineering and their fabrication methods are summarized. Moreover, recent advances in developing electroconductive materials for delivering therapeutic agents as one of emerging approaches for treating heart diseases and regenerating damaged cardiac tissues are highlighted.

Does utilization of heart machine perfusion for donation after cardiac death transplantation affect outcomes of other abdominal transplanted organs?

INTRODUCTION

Machine perfusion of heart for donation after circulatory death (DCD) is being increasingly utilized. Current protocols for utilizing heart DCD's machine perfusion might prolong donor warm ischemic time for nonheart organs. The aim of this study was to analyze the effects of utilizing heart machine perfusion on liver and kidney transplants from the same donor.

METHODS

We analyzed data of DCD donors from the United Network for Organ Sharing (UNOS) from January-2020 to September-2021 among two groups: donors with heart machine perfusion (HM) and without heart machine perfusion (NHM). Propensity score (PS) matching was performed to compare the short-term outcomes of liver and kidney transplants between two groups.

RESULTS

Total of 102 liver and 319 kidney transplants were performed using organs from donors with HM. After PS matching, no statistically significant difference was seen in 1-year graft survival (GS) for both liver and kidney transplants between two groups (liver HM 90.6% vs. NHM 90.2%, p = .47; kidney HM 95.2% vs. NHM 92.9%, p = .40). There was no difference in the delayed graft function (DGF) rates in kidney transplantation (KT) (HM 42% vs. NHM 35%, p = .062).

CONCLUSION

Utilization of heart machine perfusion in DCD donors had no significant impact on 1-year outcomes of liver and kidney transplantation.

Emergency department use and hospital admissions among adult orthotopic heart transplant patients

Objective

To study the demographics, clinical presentations, and outcomes of emergency department (ED) visits of patients with heart transplantation (HT) in the United States.

Methods

We performed a secondary analysis of the National Emergency Department Sample database from 2016 to 2018. All ED visits of patients with HT aged ≥ 18 years were identified using International Classification of Diseases, Tenth Revision codes.

Results

Out of a total 308,182,495 national ED visits, 55,583 were HT‐related visits. The median age was 61.07 years (interquartile range [IQR]: 46.91–69.38) and 69.44% were males. The hospital admission rate was 54.3% and median inpatient length of stay was 3.19 days (IQR: 1.63–5.92). The mortality rate during inpatient stay was 1.16%. Median inpatient and ED charges among admitted patients were $37,911 (IQR: $21,487–$71,262). The most common primary diagnosis of HT‐related ED visits was sepsis (4.3%) followed by acute kidney injury (3.57%) and chest pain (3%).

Conclusion

More than half of total ED visits among HT patients resulted in hospital admission. The most common cause for ED visit in these patients was sepsis followed by acute kidney injury and chest pain.

Critical warm ischemia time point for cardiac donation after circulatory death

Donation after circulatory death (DCD) represents a promising opportunity to overcome the relative shortage of donors for heart transplantation. However, the necessary period of warm ischemia is a concern. This study aims to determine the critical warm ischemia time based on in vivo biochemical changes. Sixteen DCD non-cardiac donors, without cardiovascular disease, underwent serial endomyocardial biopsies immediately before withdrawal of life-sustaining therapy (WLST), at circulatory arrest (CA) and every 2 min thereafter. Samples were processed into representative pools to assess calcium homeostasis, mitochondrial function and cellular viability. Compared to baseline, no significant deterioration was observed in any studied parameter at the time of CA (median: 9 min; IQR: 7-13 min; range: 4-19 min). Ten min after CA, phosphorylation of cAMP-dependent protein kinase-A on Thr197 and SERCA2 decreased markedly; and parallelly, mitochondrial complex II and IV activities decreased, and caspase 3/7 activity raised significantly. These results did not differ when donors with higher WLST to CA times (≥9 min) were analyzed separately. In human cardiomyocytes, the period from WLST to CA and the first 10 min after CA were not associated with a significant compromise in cellular function or viability. These findings may help to incorporate DCD into heart transplant programs.

Apelin-13 Pretreatment Promotes the Cardioprotective Effect of Mesenchymal Stem Cells against Myocardial Infarction by Improving Their Survival

Although mesenchymal stem cell- (MSC-) based therapy has shown promising results for myocardial infarction (MI), low cell survival heavily limits its beneficial effects. Apelin plays an essential regulatory role in cell proliferation. This study was aimed at determining whether Apelin-13 pretreatment could improve the survival of MSCs in the ischemic heart and enhance their cardioprotective efficacy against MI. MSCs were pretreated with or without Apelin-13 for 24 hours and then exposed to serum deprivation and hypoxia (SD/H) for 48 hours. The mitochondrial morphology of MSCs was assessed by MitoTracker staining. The apoptosis of MSCs was determined by TUNEL staining. The level of mitochondrial reactive oxygen species (ROS) of MSCs was detected by Mito-Sox staining. MSCs and Apelin-13-pretreated MSCs were transplanted into the peri-infarct region in a mouse MI model. Apelin-13 pretreatment protected MSCs against SD/H-induced mitochondrial fragmentation and apoptosis. Apelin-13 pretreatment reduced ROS generation induced by SD/H in MSCs. Furthermore, Apelin-13 pretreatment enhanced the angiogenesis of MSCs under SD/H conditions. Mechanistically, Apelin-13 pretreatment inhibited SD/H-induced MSC apoptosis by downregulating mitochondrial fission via activation of the ERK pathway, and these effects were partially abrogated by ERK inhibitor U0126. Apelin-13 pretreatment promoted the survival of MSCs in the ischemic heart. Moreover, transplantation with Apelin-13-pretreated MSCs improved heart function and increased angiogenesis accompanied by decreased fibrosis compared with MSC transplantation at 28 days following MI. These findings reveal that pretreatment with Apelin-13 improves MSCs survival and enhances their therapeutic efficacy for MI. Our study provides a novel approach to improve MSC-based therapy for cardiovascular disease.

Predictors of Hypertension Development 1 Y After Heart Transplantation

BACKGROUND

Hypertension after heart transplantation (HTx) is common. We investigated predictors of and mechanisms for hypertension development during the first year after HTx, with particular attention toward immunosuppressive agents, reinnervation processes, and donor/recipient sex.

METHODS

Heart transplant recipients (HTxRs) were consecutively enrolled 7 to 12 wk after surgery and followed prospectively for 12 mo. Ambulatory blood pressure recordings and autonomic cardiovascular control assessments were performed at baseline and follow-up. Possible predictors of posttransplant hypertension development were investigated in bivariate linear regression analyses followed by multiple regression modeling.

RESULTS

A total of 50 HTxRs were included; 47 attended the follow-up appointment at 12 mo. Mean systolic and diastolic blood pressure increased significantly during the observational period (systolic blood pressure from 133 to 139 mm Hg, P = 0.007; diastolic blood pressure from 81 to 84 mm Hg, P = 0.005). The blood pressure increment was almost exclusively confined to HTxRs with a female donor heart, doubling the cases of systolic hypertension (from 6 to 13/14; 46% to 93%, P = 0.031) and diastolic hypertension (from 7 to 14/14; 54% to 100%, P = 0.031) in this subgroup. Autonomic cardiovascular control assessments suggested tonically constricted resistance and capacitance vessels in recipients with female donor hearts. Immunosuppressive agents and reinnervation markers were not associated with hypertension development.

CONCLUSIONS

Blood pressures increase during the first year after HTx, with female donor sex as a strong predictor of recipient hypertension development. The underlying mechanism seems to be enhanced peripheral vasoconstriction caused by attenuated cardiovascular homeostasis capabilities. Further studies are needed to confirm the results.

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.

Association of tacrolimus time-to-therapeutic range on renal dysfunction and acute cellular rejection after orthotopic heart transplantation in a high use basiliximab population

BACKGROUND

Currently, clinicians often delay initiation of tacrolimus after orthotopic heart transplantation (OHT) to help mitigate nephrotoxicity. This study aimed to determine if there is an association between the time-to-therapeutic range (TTT) of tacrolimus, early renal dysfunction, and acute cellular rejection (ACR) after OHT.

METHODS

This was a retrospective, single center study with adult patients who underwent OHT from July 2013 to April 2020. Logistic regression analysis was utilized to examine the association of TTT with new renal dysfunction after tacrolimus initiation post-OHT.

RESULTS

In a study of 317 patients, the unadjusted analysis showed patients who developed new renal dysfunction after tacrolimus initiation had a numerically shorter TTT (9.5 vs. 11.0 days, P = .065), and were more likely to have supratherapeutic tacrolimus levels (56% vs. 39.2%, P = .010). When adjusted for established risk factors for renal dysfunction, TTT was significantly associated with new renal dysfunction (OR .95; 95% CI [.90, .99], P = .03). There was no association between TTT and the incidence of ACR (11.1 vs. 10.8 days, P = .64).

CONCLUSION

When adjusting for known risk factors, a shorter TTT was associated with new renal dysfunction. Supratherapeutic tacrolimus levels were also associated with new renal dysfunction. There was no association between TTT and ACR in the setting of high use basiliximab induction.

Post-transplantation outcomes of sensitized patients receiving durable mechanical circulatory support

BACKGROUND

Sensitization, defined as the presence of circulating antibodies, presents challenges, particularly in patients undergoing heart transplantation (HTx) bridged with durable mechanical circulatory support (MCS). We aimed to investigate the post-transplantation outcomes of sensitized MCS patients.

METHODS

Among 889 consecutively enrolled heart transplant (HTx) recipients between 2010 and 2018, 86 (9.7%) sensitized MCS patients (Group A) were compared with sensitized non-MCS patients (Group B, n = 189), non-sensitized MCS patients (Group C, n = 162), and non-sensitized non-MCS patients (Group D, n = 452) regarding post-HTx outcomes, including the incidence of primary graft dysfunction (PGD), 1-year survival, and 1-year freedom from antibody-mediated rejection (AMR).

RESULTS

Sensitized MCS patients (Group A) showed comparable rates of PGD, 1-year survival, and 1-year freedom from AMR with Groups C and D. However, Group A showed significantly higher rates of 1-year freedom from AMR (95.3% vs 85.7%, p = 0.02) and an earlier decline in panel-reactive antibody (PRA) levels (p < 0.01) than sensitized non-MCS patients (Group B). Desensitization therapy effectively reduced the levels of PRA in both Groups A and B. When Group A was further divided according to the presence of preformed donor-specific antibodies (DSA), patients with preformed DSA showed significantly lower rates of 1-year freedom from AMR than those without (84.2% vs 98.5%, p = 0.01).

CONCLUSIONS

Sensitized MCS patients showed significantly lower rates of AMR and an earlier decline in PRA levels following HTx than sensitized non-MCS patients. Removal of MCS at the time of transplantation might underlie these observations.

Trends, risk factors, and outcomes of post-operative stroke after heart transplantation: an analysis of the UNOS database

BACKGROUND

Post-operative stroke increases morbidity and mortality after cardiac surgery. Data on characteristics and outcomes of stroke after heart transplantation (HTx) are limited.

METHODS AND RESULTS

We conducted a retrospective analysis of the United Network for Organ Sharing (UNOS) database from 2009 to 2020 to identify adults who developed stroke after orthotropic HTx. Heart transplant recipients were divided according to the presence or absence of post-operative stroke. The primary endpoint was all-cause mortality. A total of 25 015 HT recipients were analysed, including 719 (2.9%) patients who suffered a post-operative stroke. The stroke rates increased from 2.1% in 2009 to 3.7% in 2019, and the risk of stroke was higher after the implantation of the new allocation system [odds ratio 1.29, 95% confidence intervals (CI) 1.06-1.56, P = 0.01]. HTx recipients with post-operative stroke were older (P = 0.008), with higher rates of prior cerebrovascular accident (CVA) (P = 0.004), prior cardiac surgery (P < 0.001), longer waitlist time (P = 0.04), higher rates of extracorporeal membrane oxygenation (ECMO) support (P < 0.001), left ventricular assist devices (LVADs) (P < 0.001), mechanical ventilation (P = 0.003), and longer ischaemic time (P < 0.001). After multivariable adjustment for recipient and donor characteristics, age, prior cardiac surgery, CVA, support with LVAD, ECMO, ischaemic time, and mechanical ventilation at the time of HTx were independent predictors of post-operative stroke. Stroke was associated with increased risk of 30 day and all-cause mortality (hazard ratio 1.49, 95% CI 1.12-1.99, P = 0.007).

CONCLUSIONS

Post-operative stroke after HTx is infrequent but associated with higher mortality. Redo sternotomy, LVAD, and ECMO support at HTx are among the risk factors identified.

Characteristics and Outcomes of Patients with Inflammatory Cardiomyopathies Receiving Mechanical Circulatory Support: An STS-INTERMACS Registry Analysis

BACKGROUND

Durable mechanical circulatory support (MCS) therapy improves survival in patients with advanced heart failure. Knowledge regarding the outcomes experienced by patients with inflammatory cardiomyopathy (CM) who receive durable MCS therapy is limited.

METHODS AND RESULTS

We compared patients with inflammatory CM with patients with idiopathic dilated CM enrolled in the STS-INTERMACS registry. Among 19,012 patients, 329 (1.7%) had inflammatory CM and 5978 had idiopathic dilated CM (31.4%). The patients with inflammatory CM were younger, more likely to be White, and women. These patients experienced more preoperative arrhythmias and higher use of temporary MCS. Patients with inflammatory CM had a higher rate of early adverse events (<3 months after device implant), including bleeding, arrhythmias, non-device-related infections, neurologic dysfunction, and respiratory failure. The rate of late adverse events (≥3 months) was similar in the 2 groups. Patients with inflammatory CM had a similar 1-year (80% vs 84%) and 2-year (72% vs 76%, P = .15) survival. Myocardial recovery resulting in device explant was more common among patients with inflammatory CM (5.5% vs 2.3%, P < .001).

CONCLUSIONS

Patients with inflammatory CM who received durable MCS appear to have a similar survival compared with patients with idiopathic dilated CM despite a higher early adverse event burden. Our findings support the use of durable MCS in an inflammatory CM population.

Effect of novel bicaval anastomosis technique for transplantation with and without prior cardiac surgery history

Background

To evaluate the graft outcomes after orthotopic heart transplantation (HTx) with a novel bicaval anastomosis technique between recipients with and without a history of prior cardiac surgery.

Methods

Of 70 patients who underwent HTx with a novel four-corners traction bicaval anastomosis technique from August 2017 to November 2019, 60 recipients underwent the HTx procedure as their first cardiac surgery (group A), while 10 recipients underwent HTx after prior cardiac surgery (group B). Patients in the two groups were compared in terms of their preoperative baseline variables such as etiological categories, history of blood transfusion and panel reactive antibody (PRA), intraoperative operation time and blood infusion volume, postoperative treatment time, and complications such as acute rejection and 30-day mortality as well as survival rates.

Results

Preoperative variables were comparable in group A and group B except for the history of blood transfusion (0% vs. 90.0%, P<0.001, respectively); the level of PRA was 7.5%±5.8% and 9.5%±10.9% for group A and B, respectively (P=0.583), but the time of the operation was nearly 1 hour longer for group B than group A (all P<0.05). No cases of left atrial thrombosis and donor heart distortion were observed in either group. Reoperation (1.7% vs. 10.0%, P=0.267), infection (0% vs. 10.0%, P=0.142), other postoperative complications as well as the 30-day mortality (1.7% vs. 10.0%, P=0.267), and postoperative survival rates (91.5% vs. 90.0%, P=0.805) were comparable between the two groups (all P>0.05).

Conclusions

Four-corner traction bicaval anastomosis combined with a continuous everting suture technique may result in approximately comparable prognoses for heart recipients with a history of cardiac surgery when compared with those without a history of cardiac surgery and this technique may reduce the incidence of left atrial thrombosis and distortion. Further follow-up of the long-term outcomes will be required to validate these results.

Ablation of Survivin in T Cells Attenuates Acute Allograft Rejection after Murine Heterotopic Heart Transplantation by Inducing Apoptosis

Although studies in oncology have well explored the pharmacological effects of Birc5, little is known about its role in allogeneic T-cell responses. Therefore, the present study used a mouse model of acute heart allograft rejection to investigate the protective effect and mechanism of conditional knockout of Birc5 in T cells. Survivin (encoded by Birc5) was up-regulated in T cells activated in vivo and in vitro. Deletion of Birc5 in T cells attenuated acute heart allograft rejection by reducing the ratio of effector to naive T cells and Th1 to Tregs. In addition, deletion of Birc5 had no noticeable effect on proliferation but on apoptosis and the secretion of IFN-γ. The results revealed a significant increase in the percentage of Annexin V positive CD4⁺ T cells in the Birc5^-/- group, compared to the WT. Moreover, there was significant increase in early apoptotic alloreactive T cells in Birc5^-/- mice and this was partly mediated by caspase-3. Furthermore, treatment with YM155 inhibited acute heart allograft rejection in vivo and increased T-cell apoptosis in healthy human PBMCs in vitro. The results highlight a potential therapeutic target for the prevention and treatment of acute transplant rejection.

Advanced heart failure and heart transplantation in adult congenital heart disease in the current era

BACKGROUND

Adults with congenital heart disease (ACHD) may undergo heart transplantation (HTx) despite increased risk of poor short-term outcomes due to factors including surgical complexity and antibody sensitization. We assessed the clinical characteristics and outcomes of patients with ACHD in the current era referred for HTx at a single high-volume transplant center.

METHODS

From 2010-2020, 37 ACHD patients were evaluated for HTx. ACHD HTx recipients were compared to non-ACHD HTx recipients matched for age, sex, listing status, and prior cardiac surgery.

RESULTS

Of the 37 patients with ACHD, 8 (21.6%) were declined for HTx. Of 29 ACHD patients listed, 19 (65.5%) underwent HTx. Compared with non-ACHD HTx controls, the ACHD HTx recipients had more treated cellular (21.1% vs 15.8%, p = 0.010) and antibody-mediated (15.8% vs 10.5%, p = 0.033) rejection. There was no difference in hospital readmission or allograft vasculopathy at 1 year. There was a nonsignificant higher 1-year mortality in ACHD HTx recipients (21.1% vs 7.9%, p = 0.21).

CONCLUSION

At a high-volume transplant center, ACHD patients undergoing HTx appear to have a marginally higher risk of rejection, but no significant increase in 1-year mortality. With careful selection and management, HTx for patients with ACHD may be feasible in the current era. This article is protected by copyright. All rights reserved.

Outcome of urgent desensitization in sensitized heart transplant recipients

BACKGROUND/PURPOSE

Sensitization, the presence of preformed anti-human antibody in recipients, restricts access to ABO-compatible donors in heart transplant. Desensitization therapy works by reducing preformed antibodies to increase the chances of a negative crossmatch or permit safe transplantation across positive crossmatch. There is no consensus regarding the desensitization protocol in cardiac patients, and the outcome of desensitization remains under debate.

METHODS

Twenty-five consecutive sensitized heart transplant recipients received perioperative desensitization in our institution from 2012 to 2019. One-year patient survival and graft rejection rate were analyzed and compared between sensitized recipients and non-sensitized recipients.

RESULTS

Within the first year after transplant, patient survival in sensitized recipients was 76%. Infection was the major cause of death. The cumulative incidence of rejection was 8% for antibody-mediated rejection and 16% for acute cellular rejection. No significant difference in 1-year survival or rejection rate could be demonstrated between sensitized and nonsensitized recipients.

CONCLUSION

Acceptable early outcomes in patient survival and graft rejection could be anticipated in sensitized heart transplant recipients under a perioperative algorithm using complement-dependent cytotoxicity crossmatch- or panel-reactive antibody-directed urgent immunomodulation strategies, while infection remains the major concern.

Posterior Reversible Encephalopathy Syndrome Associated with Tacrolimus in Cardiac Transplantation

Background

Neurological complications occur between 50 and 70% of patients with heart transplantation, including cerebrovascular events, infections, seizures, encephalopathy, and neurotoxicity due to pharmacological immunosuppression. Mortality associated with cerebrovascular complications is 7.5% in the first 30 days and up to 5.3% after the first month and up to the first year after transplantation. Case Reports. Three heart-transplanted patients (2 men and 1 woman) treated with tacrolimus were identified. They presented with posterior reversible encephalopathy syndrome on days 5, 6, and 58 posttransplantation, respectively. In these reported cases, no sequelae were observed at 6 months follow-up.

Conclusions

Posterior reversible encephalopathy syndrome as a neurological complication in patients with HT occurred early after the procedure. Early diagnosis and treatment might reduce the risk of serious complications and mortality.

State-of-the-art machine learning algorithms for the prediction of outcomes after contemporary heart transplantation: Results from the UNOS database

PURPOSE

We sought to develop and validate machine learning (ML) models to increase the predictive accuracy of mortality after heart transplantation (HT).

METHODS AND RESULTS

We included adult HT recipients from the United Network for Organ Sharing (UNOS) database between 2010 and 2018 using solely pre-transplant variables. The study cohort comprised 18 625 patients (53 ± 13 years, 73% males) and was randomly split into a derivation and a validation cohort with a 3:1 ratio. At 1-year after HT, there were 2334 (12.5%) deaths. Out of a total of 134 pre-transplant variables, 39 were selected as highly predictive of 1-year mortality via feature selection algorithm and were used to train five ML models. AUC for the prediction of 1-year survival was .689, .642, .649, .637, .526 for the Adaboost, Logistic Regression, Decision Tree, Support Vector Machine, and K-nearest neighbor models, respectively, whereas the Index for Mortality Prediction after Cardiac Transplantation (IMPACT) score had an AUC of .569. Local interpretable model-agnostic explanations (LIME) analysis was used in the best performing model to identify the relative impact of key predictors. ML models for 3- and 5-year survival as well as acute rejection were also developed in a secondary analysis and yielded AUCs of .629, .609, and .610 using 27, 31, and 91 selected variables respectively.

CONCLUSION

Machine learning models showed good predictive accuracy of outcomes after heart transplantation.

Osteopontin and Transplantation: Where Are We Now?

Organ transplantation represents the optimal therapeutic tool for patients with end-stage organ failure. Hematopoietic stem cell transplantation (HSCT) is likewise an effective therapy for a wide range of malignant and non-malignant diseases. Better understanding of transplantation immunology and the use of multi-modal immunosuppression protocols, can decrease the risk of graft failure and graft-versus-host disease (GVHD) after HSCT. Nevertheless, a major challenge of modern transplantology still seems to be finding non-invasive biomarkers for recipients selection, monitoring of allograft function, and diagnosis of rejection. Since proinflammatory cytokine osteopontin (OPN) is closely involved in regulating both adaptive and innate immune responses, as well as the pathogenesis of inflammatory and autoimmune diseases, it is likely to play an important role in organ and HSC transplantation. This review is to summarize recent advances in our knowledge about OPN function in the kidney, heart, liver, lung, and HSC transplantation. Most studies found that elevated OPN is associated with poorer graft function in kidney, heart, liver and lung recipients. Moreover, some reports suggested that this protein can play role in GVHD pathogenesis. However, due to relatively small number of similar studies, as well as some inconclusive results, future investigation in this field is needed to verify if OPN can serve as a biomarker of organ and HSC transplantation. The knowledge about such markers will promote our understanding of the mechanisms underlying graft dysfunction and posttransplant mortality. In addition, such knowledge may be helpful in the development of new treatment strategies and identification of recipients with increased risk of allograft failure.

Endogenous Cardiotonics: Search And Problems

Medicinal preparations currently used for the treatment of patients with chronic cardiac failure involve those that reduce the heart load (vasodilators, diuretics, beta-blockers, and angiotensin-converting enzyme (ACE) inhibitors). Cardiotonic drugs with the cAMP-dependent mechanism are unsuitable for long-term administration due to the intensification of metabolic processes and an increase in the oxygen demand of the myocardium and all tissues of the body. For many years, digoxin has remained the only preparation enhancing the efficiency of myocardial performance. The detection of digoxin and ouabain in intact animals has initiated a search for other compounds with cardiotonic activity. The review summarizes current data on the effect exerted on the heart performance by endogenous compounds, from simple, such as NO and CO, to steroids, fatty acids, polypeptides, and proteins. Controversial questions and problems with the introduction of scientific achievements into clinical practice are discussed. The results obtained by the authors and their colleagues after many years of studies on the cardiotropic properties of serum lipoproteins are also reported. The experimentally established cardiotonic activity of apoprotein A-1, which is accompanied by a decrease in the relative consumption of oxygen, maybe of great interest.