Outcomes in Heart Transplant Recipients by Bridge to Transplant Strategy When Using the SherpaPak Cardiac Transport System

The last several years have seen a rise in use of mechanical circulatory support (MCS) to bridge heart transplant recipients. A controlled hypothermic organ preservation system, the SherpaPak Cardiac Transport System (SCTS), was introduced in 2018 and has grown in utilization with reports of improved posttransplant outcomes. The Global Utilization And Registry Database for Improved heArt preservatioN (GUARDIAN)-Heart registry is an international, multicenter registry assessing outcomes after transplant using the SCTS. This analysis examines outcomes in recipients bridged with various MCS devices in the GUARDIAN-Heart Registry. A total of 422 recipients with donor hearts transported using SCTS were included and identified. Durable ventricular assist devices (VADs) were used exclusively in 179 recipients, temporary VADs or intra-aortic balloon pump (IABP) in 197, and extracorporeal membrane oxygenation (ECMO) in 14 recipients. Average ischemic times were over 3.5 hours in all cohorts. Severe primary graft dysfunction (PGD) posttransplant increased across groups (4.5% VAD, 5.1% temporary support, 21.4% ECMO), whereas intensive care unit (ICU) length of stay (18.2 days) and total hospital stay (39.4 days) was longer in the ECMO cohort than the VAD and IABP groups. A comparison of outcomes of MCS bridging in SCTS versus traditional ice revealed significantly lower rates of both moderate/severe right ventricular (RV) dysfunction and severe PGD in the SCTS cohort; however, upon propensity matching only the reductions in moderate/severe RV dysfunction were statistically significant. Use of SCTS in transplant recipients with various bridging strategies results in excellent outcomes.

Recipient Outcomes With Extended Criteria Donors Using Advanced Heart Preservation: An Analysis of the GUARDIAN-Heart Registry

BACKGROUND

The prevalence of end-stage heart failure and patients who could benefit from heart transplantation requires an expansion of the donor pool, relying on the transplant community to continually re-evaluate and expand the use of extended criteria donor organs. Introduction of new technologies such as the Paragonix SherpaPak Cardiac Transport System aids in this shift. We seek to analyze the impact of the SherpaPak system on recipient outcomes who receive extended criteria organs in the GUARDIAN-Heart Registry.

METHODS

Between October 2015 and December 2022, 1,113 adults from 15 US centers receiving donor hearts utilizing either SherpaPak (n = 560) or conventional ice storage (ice, n = 453) were analyzed from the GUARDIAN-Heart Registry using summary statistics. A previously published set of criteria was used to identify extended criteria donors, which included 193 SherpaPak and 137 ice.

RESULTS

There were a few baseline differences among recipients in the 2 cohorts; most notably, IMPACT scores, distance traveled, and total ischemic time were significantly greater in SherpaPak, and significantly more donor hearts in the SherpaPak cohort had >4 hours total ischemia time. Posttransplant mechanical circulatory support utilization (SherpaPak 22.3% vs ice 35.0%, p = 0.012) and new extracorporeal membrane oxygenation/ventricular assist device (SherpaPak 7.8% vs ice 15.3%, p = 0.033) was significantly reduced, and the rate of severe primary graft dysfunction (SherpaPak 6.2% vs ice 13.9%, p = 0.022) was significantly reduced by over 50% in hearts preserved using SherpaPak. One-year survival between cohorts was similar (SherpaPak 92.9% vs ice 89.6%, p = 0.27).

CONCLUSIONS

This subgroup analysis demonstrates that SherpaPak can be safely used to utilize extended criteria donors with low severe PGD rates.

Impact of controlled hypothermic preservation on outcomes following heart transplantation

BACKGROUND

Severe primary graft dysfunction (PGD) is a major cause of early mortality after heart transplant, but the impact of donor organ preservation conditions on severity of PGD and survival has not been well characterized.

METHODS

Data from US adult heart-transplant recipients in the Global Utilization and Registry Database for Improved Heart Preservation-Heart Registry (NCT04141605) were analyzed to quantify PGD severity, mortality, and associated risk factors. The independent contributions of organ preservation method (traditional ice storage vs controlled hypothermic preservation) and ischemic time were analyzed using propensity matching and logistic regression.

RESULTS

Among 1,061 US adult heart transplants performed between October 2015 and December 2022, controlled hypothermic preservation was associated with a significant reduction in the incidence of severe PGD compared to ice (6.6% [37/559] vs 10.4% [47/452], p = 0.039). Following propensity matching, severe PGD was reduced by 50% (6.0% [17/281] vs 12.1% [34/281], respectively; p = 0.018). The Kaplan-Meier terminal probability of 1-year mortality was 4.2% for recipients without PGD, 7.2% for mild or moderate PGD, and 32.1%, for severe PGD (p < 0.001). The probability of severe PGD increased for both cohorts with longer ischemic time, but donor hearts stored on ice were more likely to develop severe PGD at all ischemic times compared to controlled hypothermic preservation.

CONCLUSIONS

Severe PGD is the deadliest complication of heart transplantation and is associated with a 7.8-fold increase in probability of 1-year mortality. Controlled hypothermic preservation significantly attenuates the risk of severe PGD and is a simple yet highly effective tool for mitigating post-transplant morbidity.

Beating Heart Transplant Procedures Using Organs From Donors With Circulatory Death

Importance

The use of ex vivo normothermic organ perfusion has enabled the use of deceased after circulatory death (DCD) donors for heart transplants. However, compared with conventional brain death donation, DCD heart transplantation performed with ex vivo organ perfusion involves an additional period of warm and cold ischemia, exposing the allograft to multiple bouts of ischemia reperfusion injury and may contribute to the high rates of extracorporeal membrane oxygenation usage after DCD heart transplantation.

Objective

To assess whether the beating heart method of DCD heart transplantation is safe and whether it has an acceptable rate of extracorporeal membrane oxygenation use postoperatively.

Design, Setting, and Participants

This case series includes 10 patients with end-stage heart failure undergoing DCD heart transplantation at a single academic medical center from October 1, 2022, to August 3, 2023. Data were analyzed from October 2022 to August 2023.

Interventions

Using a beating heart method of implantation of the donor allograft.

Main Outcomes and Measures

The main outcome was primary graft dysfunction necessitating postoperative initiation of mechanical circulatory support. Survival and initiation of mechanical circulatory support were secondary outcomes.

Results

In this case series, 10 consecutive patients underwent DCD heart transplantation via the beating heart method. Ten of 10 recipients were male (100%), the mean (SD) age was 51.2 (13.8) years, and 7 (70%) had idiopathic dilated cardiomyopathy. Ten patients (100%) survived, and 0 patients had initiation of extracorporeal membrane oxygenation postoperatively. No other mechanical circulatory support, including intra-aortic balloon pump, was initiated postoperatively. Graft survival was 100% (10 of 10 patients), and, at the time of publication, no patients have been listed for retransplantation.

Conclusions and Relevance

In this study of 10 patients undergoing heart transplantation, the beating heart implantation method for DCD heart transplantation was safe and may mitigate ischemia reperfusion injury, which may lead to lower rates of primary graft dysfunction necessitating extracorporeal membrane oxygenation. These results are relevant to institutions using DCD donors for heart transplantation.

Increasing Utilization of Extended Criteria Donor Hearts for Transplantation: The OCS Heart EXPAND Trial

BACKGROUND

Extended criteria donor (ECD) hearts available with donation after brain death (DBD) are underutilized for transplantation due to limitations of cold storage.

OBJECTIVES

This study evaluated use of an extracorporeal perfusion system on donor heart utilization and post-transplant outcomes in ECD DBD hearts.

METHODS

In this prospective, single-arm, multicenter study, adult heart transplant recipients received ECD hearts using an extracorporeal perfusion system if hearts met study criteria. The primary outcome was a composite of 30-day survival and absence of severe primary graft dysfunction (PGD). Secondary outcomes were donor heart utilization rate, 30-day survival, and incidence of severe PGD. The safety outcome was the mean number of heart graft-related serious adverse events within 30 days. Additional outcomes included survival through 2 years benchmarked to concurrent nonrandomized control subjects.

RESULTS

A total of 173 ECD DBD hearts were perfused; 150 (87%) were successfully transplanted; 23 (13%) did not meet study transplantation criteria. At 30 days, 92% of patients had survived and had no severe PGD. The 30-day survival was 97%, and the incidence of severe PGD was 6.7%. The mean number of heart graft-related serious adverse events within 30 days was 0.17 (95% CI: 0.11-0.23). Patient survival was 93%, 89%, and 86% at 6, 12, and 24 months, respectively, and was comparable with concurrent nonrandomized control subjects.

CONCLUSIONS

Use of an extracorporeal perfusion system resulted in successfully transplanting 87% of donor hearts with excellent patient survival to 2 years post-transplant and low rates of severe PGD. The ability to safely use ECD DBD hearts could substantially increase the number of heart transplants and expand access to patients in need. (International EXPAND Heart Pivotal Trial [EXPANDHeart]; NCT02323321; Heart EXPAND Continued Access Protocol; NCT03835754).

Four decades of progress in heart-lung transplantation: Two hundred seventy-one cases at a single institution

OBJECTIVE

The objective of this study is to evaluate survival for combined heart-lung transplant (HLTx) recipients across 4 decades at a single institution. We aim to summarize our contemporary practice based on more than 271 HLTx procedures over 40 years.

METHODS

Data were collected from a departmental database and the United Network for Organ Sharing. Recipients younger than age 18 years, those undergoing redo HLTx, or triple-organ system transplantation were excluded, leaving 271 patients for analysis. The pioneering era was defined by date of transplant between 1981 and 2000 (n = 155), and the modern era between 2001 and 2022 (n = 116). Survival analysis was performed using cardinality matching of populations based on donor and recipient age, donor and recipient sex, ischemic time, and sex matching.

RESULTS

Between 1981 and 2022, 271 HLTx were performed at a single institution. Recipients in the modern era were older (age 42 vs 34 y; P < .001) and had shorter waitlist times (78 vs 234 days; P < .001). Allografts from female donors were more common in the modern era (59% vs 39%; P = .002). In the matched survival analysis, 30-day survival (97% vs 84%; P = .005), 1-year survival (89% vs 77%; P = .041), and 10-year survival (53% vs 26%; P = .012) significantly improved in the modern era relative to the pioneering era, respectively.

CONCLUSIONS

Long-term survival in HLTx is achievable with institutional experience and may continue to improve in the coming decades. Advances in mechanical circulatory support, improved maintenance immunosuppression, and early recognition and management of acute complications such as primary graft dysfunction and acute rejection have dramatically improved the prognosis for recipients of HLTx in our contemporary institutional experience.

Revised Heart Allocation Policy Improved Waitlist Mortality and Waiting Time With Maintained Outcomes in En-Bloc Heart-Lung Transplant Candidates and Recipients

The revised United Network for Organ Sharing heart allocation policy was implemented in October 2018. Using a national transplant database, this study evaluated the transplant rate, waitlist mortality, waiting time, and other outcomes of en-bloc heart-lung transplantation recipients. Adult patients registered on the national database for heart-lung transplants before and after the policy update were selected as cohorts. Baseline characteristics, transplant rates, waitlist mortality, waiting times, and other outcomes were compared between the two periods. In total, 370 patients were registered for heart-lung transplants during the pre- and post-periods. There were significantly higher transplant rates, shorter waitlist times, and substantially reduced waitlist mortality in the post-period. Registered patients waitlisted in the post-period had significantly higher utilization of intra-aortic balloon pumps, extracorporeal membrane oxygenation, and overall life support, including ventricular assist devices. Transplant recipients had significantly longer ischemic times, increased transport distances, and shorter waiting times before transplantation in the post-policy period. Transplant recipients held similar short-term survival before and after the policy change (log-rank test, p = 0.4357). Therefore, the revised policy significantly improved access to en-bloc heart-lung allografts compared with the prior policy, with better waitlist outcomes and similar post-transplant outcomes.

A value-based approach to optimize red blood cell transfusion in patients receiving extracorporeal membrane oxygenation

INTRODUCTION

The risk, cost, and adverse outcomes associated with packed red blood cell (RBC) transfusions in patients with cardiopulmonary failure requiring extracorporeal membrane oxygenation (ECMO) have raised concerns regarding the overutilization of RBC products. It is, therefore, necessary to establish optimal transfusion criteria and protocols for patients supported with ECMO. The goal of this study was to establish specific criteria for RBC transfusions in patients undergoing ECMO.

METHODS

This was a retrospective cohort study conducted at Stanford University Hospital. Data on RBC utilization during the entire hospital stay were obtained, which included patients aged ≥18 years who received ECMO support between 1 January 2017, and 30 June 2020 (n = 281). The primary outcome was in-hospital mortality.

RESULTS

Hemoglobin (HGB) levels >10 g/dL before transfusion did not improve in-hospital survival. Therefore, we revised the HGB threshold to ≤10 g/dL to guide transfusion in patients undergoing ECMO. To validate this intervention, we prospectively compared the pre- and post-intervention cohorts for in-hospital mortality. Post-intervention analyses found 100% compliance for all eligible records and a decrease in the requirement for RBC transfusion by 1.2 units per patient without affecting the mortality.

CONCLUSIONS

As an institution-driven value-based approach to guide transfusion in patients undergoing ECMO, we lowered the threshold HGB level. Validation of this revised intervention demonstrated excellent compliance and reduced the need for RBC transfusion while maintaining the clinical outcome. Our findings can help reform value-based healthcare in this cohort while maintaining the outcome.

A Paradigm Shift in Heart Preservation: Improved Post-transplant Outcomes in Recipients of Donor Hearts Preserved With the SherpaPak System

Traditional ice storage has been the historic standard for preserving donor's hearts. However, this approach provides variability in cooling, increasing risks of freezing injury. To date, no preservation technology has been reported to improve survival after transplantation. The Paragonix SherpaPak Cardiac Transport System (SCTS) is a controlled hypothermic technology clinically used since 2018. Real-world evidence on clinical benefits of SCTS compared to conventional ice cold storage (ICS) was evaluated. Between October 2015 and January 2022, 569 US adults receiving donor hearts preserved and transported either in SCTS (n = 255) or ICS (n = 314) were analyzed from the Global Utilization And Registry Database for Improved heArt preservatioN (GUARDIAN-Heart) registry. Propensity matching and a subgroup analysis of >240 minutes ischemic time were performed to evaluate comparative outcomes. Overall, the SCTS cohort had significantly lower rates of severe primary graft dysfunction (PGD) ( p = 0.03). When propensity matched, SCTS had improving 1-year survival ( p = 0.10), significantly lower rates of severe PGD ( p = 0.011), and lower overall post-transplant MCS utilization ( p = 0.098). For patients with ischemic times >4 hours, the SCTS cohort had reduced post-transplant MCS utilization ( p = 0.01), reduced incidence of severe PGD ( p = 0.005), and improved 30-day survival ( p = 0.02). A multivariate analysis of independent risk factors revealed that compared to SCTS, use of ice results in a 3.4-fold greater chance of severe PGD ( p = 0.014). Utilization of SCTS is associated with a trend toward increased post-transplant survival and significantly lower severe PGD and MCS utilization. These findings fundamentally challenge the decades-long status quo of transporting donor hearts using ice.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Case report: Heart retransplant from a donor after circulatory death and extended transport period with normothermic perfusion

A 55-year-old man with end-stage heart failure, who had an orthotopic heart transplant 21 years prior, underwent heart retransplantation using a heart from a donor with circulatory death in a distant location and an extended transport period with normothermic ex vivo perfusion. Owing to the persistent and worsening shortage of donor hearts, this case illustrates that expanding the donor acceptance criteria to include more distant donor locations and enrolling recipients with extended criteria (e.g., heart retransplantation) is feasible.

Transplantation Outcomes with Donor Hearts after Circulatory Death

BACKGROUND

Data showing the efficacy and safety of the transplantation of hearts obtained from donors after circulatory death as compared with hearts obtained from donors after brain death are limited.

METHODS

We conducted a randomized, noninferiority trial in which adult candidates for heart transplantation were assigned in a 3:1 ratio to receive a heart after the circulatory death of the donor or a heart from a donor after brain death if that heart was available first (circulatory-death group) or to receive only a heart that had been preserved with the use of traditional cold storage after the brain death of the donor (brain-death group). The primary end point was the risk-adjusted survival at 6 months in the as-treated circulatory-death group as compared with the brain-death group. The primary safety end point was serious adverse events associated with the heart graft at 30 days after transplantation.

RESULTS

A total of 180 patients underwent transplantation; 90 (assigned to the circulatory-death group) received a heart donated after circulatory death and 90 (regardless of group assignment) received a heart donated after brain death. A total of 166 transplant recipients were included in the as-treated primary analysis (80 who received a heart from a circulatory-death donor and 86 who received a heart from a brain-death donor). The risk-adjusted 6-month survival in the as-treated population was 94% (95% confidence interval [CI], 88 to 99) among recipients of a heart from a circulatory-death donor, as compared with 90% (95% CI, 84 to 97) among recipients of a heart from a brain-death donor (least-squares mean difference, -3 percentage points; 90% CI, -10 to 3; P<0.001 for noninferiority [margin, 20 percentage points]). There were no substantial between-group differences in the mean per-patient number of serious adverse events associated with the heart graft at 30 days after transplantation.

CONCLUSIONS

In this trial, risk-adjusted survival at 6 months after transplantation with a donor heart that had been reanimated and assessed with the use of extracorporeal nonischemic perfusion after circulatory death was not inferior to that after standard-care transplantation with a donor heart that had been preserved with the use of cold storage after brain death. (Funded by TransMedics; ClinicalTrials.gov number, NCT03831048.).

Outcomes of Heart Transplantation Using a Temperature-controlled Hypothermic Storage System

BACKGROUND

The SherpaPak Cardiac Transport System is a novel technology that provides stable, optimal hypothermic control during organ transport. The objectives of this study were to describe our experience using the SherpaPak system and to compare outcomes after heart transplantation after using SherpaPak versus the conventional static cold storage method (non-SherpaPak).

METHODS

From 2018 to June 2021, 62 SherpaPak and 186 non-SherpaPak patients underwent primary heart transplantation at Stanford University with follow-up through May 2022. The primary end point was all-cause mortality, and secondary end points were postoperative complications. Optimal variable ratio matching, cox proportional hazards regression model, and Kaplan-Meier survival analyses were performed.

RESULTS

Before matching, the SherpaPak versus non-SherpaPak patients were older and received organs with significantly longer total allograft ischemic time. After matching, SherpaPak patients required fewer units of blood product for perioperative transfusion compared with non-SherpaPak patients but otherwise had similar postoperative outcomes such as hospital length of stay, primary graft dysfunction, inotrope score, mechanical circulatory support use, cerebral vascular accident, myocardial infarction, respiratory failure, new renal failure requiring dialysis, postoperative bleeding or tamponade requiring reoperation, infection, and survival.

CONCLUSIONS

In conclusion, this is one of the first retrospective comparison studies that evaluated the outcomes of heart transplantation using organs preserved and transported via the SherpaPak system. Given the excellent outcomes, despite prolonged total allograft ischemic time, it may be reasonable to adopt the SherpaPak system to accept organs from a remote location to further expand the donor pool.

World's first en bloc heart-lung transplantation using the paragonix lungguard donor preservation system

We present the first en bloc heart-lung donor transplant procurement using the Paragonix LUNGguard™ donor preservation system. This system offers reliable static hypothermic conditions designed to prevent major complications such as cold ischemic injury, uneven cooling and physical damage. While this represents a single case, the encouraging results warrant further investigation.

Combining donor derived cell free DNA and gene expression profiling for non-invasive surveillance after heart transplantation

BACKGROUND

Donor-derived cell free DNA (dd-cfDNA) and gene expression profiling (GEP) offer noninvasive alternatives to rejection surveillance after heart transplantation; however, there is little evidence on the paired use of GEP and dd-cfDNA for rejection surveillance.

METHODS

A single center, retrospective analysis of adult heart transplant recipients. A GEP cohort, transplanted from January 1, 2015 through December 31, 2017 and eligible for rejection surveillance with GEP was compared to a paired testing cohort, transplanted July 1, 2018 through June 30, 2020, with surveillance from both dd-cfDNA and GEP. The primary outcomes were survival and rejection-free survival at 1 year post-transplant.

RESULTS

In total 159 patients were included, 95 in the GEP and 64 in the paired testing group. There were no differences in baseline characteristics, except for less use of induction in the paired testing group (65.6%) compared to the GEP group (98.9%), P < .01. At 1-year, there were no differences between the paired testing and GEP groups in survival (98.4% vs. 94.7%, P = .23) or rejection-free survival (81.3% vs. 73.7% P = .28).

CONCLUSIONS

Compared to post-transplant rejection surveillance with GEP alone, pairing dd-cfDNA and GEP testing was associated with similar survival and rejection-free survival at 1 year while requiring significantly fewer biopsies.

Angiogenic stem cell delivery platform to augment post-infarction neovasculature and reverse ventricular remodeling

Many cell-based therapies are challenged by the poor localization of introduced cells and the use of biomaterial scaffolds with questionable biocompatibility or bio-functionality. Endothelial progenitor cells (EPCs), a popular cell type used in cell-based therapies due to their robust angiogenic potential, are limited in their therapeutic capacity to develop into mature vasculature. Here, we demonstrate a joint delivery of human-derived endothelial progenitor cells (EPC) and smooth muscle cells (SMC) as a scaffold-free, bi-level cell sheet platform to improve ventricular remodeling and function in an athymic rat model of myocardial infarction. The transplanted bi-level cell sheet on the ischemic heart provides a biomimetic microenvironment and improved cell-cell communication, enhancing cell engraftment and angiogenesis, thereby improving ventricular remodeling. Notably, the increased density of vessel-like structures and upregulation of biological adhesion and vasculature developmental genes, such as Cxcl12 and Notch3, particularly in the ischemic border zone myocardium, were observed following cell sheet transplantation. We provide compelling evidence that this SMC-EPC bi-level cell sheet construct can be a promising therapy to repair ischemic cardiomyopathy.

Combined Heart-Lung Transplantation Outcomes in Asian Populations: National Database Analysis

BACKGROUND

Heart-lung transplantation (HLTx) is a definitive surgical procedure for end-stage cardiopulmonary failure. Studies to understand the relationship between ethnicity and race and outcomes after HLTx are needed to uphold equitable HLTx access to the increasingly diverse U.S. population facing advanced cardiopulmonary failure.

OBJECTIVES

This study sought to examine the outcomes of HLTx recipients of Asian origin, with emphasis on the ethnic and racial disparities in the outcomes.

METHODS

We analyzed data from the United Network for Organ Sharing (UNOS) for patients of ≥18 years of age who underwent HLTx between 1987 and 2021. Propensity-score matching was performed between Asian and non-Hispanic Whites (NHWs), with a 1:3 matching ratio based on the propensity score of each patient estimated by multivariable logistic regression.

RESULTS

We identified 42 Asian and Asian American heart-lung transplant recipients and 834 NHW recipients. In the pre-matched cohort, the median survival was 1,459 days (IQR: 1,080-2,692 days) in Asian recipients after transplantation, whereas it was 1,521 days (IQR: 1,262-1,841 days) in White recipients. Of the 876 recipients, 156 transplants were successfully matched (Asian, n = 36; NHW, n = 108). Among the post-transplantation outcomes, there were no significant differences in morbidity and mortality between Asian and NHW cohorts.

CONCLUSIONS

This large-scale analysis in Asian patients will have important implications in Asian countries that have relatively fewer HLTx surgeries. An outcome equivalent to NHW in Asian patients, as demonstrated in our study, could be the driving force for further expansion of HLTx surgeries in Asian countries.

Post-Transplant Extracorporeal Membrane Oxygenation for Severe Primary Graft Dysfunction to Support the Use of Marginal Donor Hearts

Severe primary graft dysfunction (PGD) is the leading cause of early postoperative mortality following orthotopic heart transplantation (OHT). Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) has been used as salvage therapy. This study aimed to evaluate the outcomes in adult OHT recipients who underwent VA-ECMO for severe PGD. We retrospectively reviewed 899 adult (≥18 years) patients who underwent primary OHT at our institution between 1997 and 2017. Recipients treated with VA-ECMO (19, 2.1%) exhibited a higher incidence of previous cardiac surgery (p = .0220), chronic obstructive pulmonary disease (p = .0352), and treatment with a calcium channel blocker (p = .0018) and amiodarone (p = .0148). Cardiopulmonary bypass (p = .0410) and aortic cross-clamp times (p = .0477) were longer in the VA-ECMO cohort and they were more likely to have received postoperative transfusion (p = .0013); intra-aortic balloon pump (IABP, p < .0001), and reoperation for bleeding or tamponade (p < .0001). The 30-day, 1-year, and overall survival after transplantation of non-ECMO patients were 95.9, 88.8, and 67.4%, respectively, compared to 73.7, 57.9, and 47.4%, respectively in the ECMO cohort. Fourteen (73.7%) of the ECMO patients were weaned after a median of 7 days following OHT (range: 1-12 days). Following OHT, VA-ECMO may be a useful salvage therapy for severe PGD and can potentially support the usage of marginal donor hearts.

Extended Static Hypothermic Preservation In Cardiac Transplantation: A Case Report

BACKGROUND

The donor shortage poses a major limitation to use of heart transplantation. Novel strategies such as use of expanded-criteria donors with prolonged ischemia times are being employed to address this need. Recent developments in static hypothermia have allowed for the safe use of cardiac allografts with prolonged ischemic times.

CASE REPORT

We present the case of a 68-year-old woman with valvular cardiomyopathy refractory to medical therapy who underwent orthotopic heart transplantation with a cardiac allograft exposed to elevated ischemic times. This was achieved through use of the federally approved SherpaPak Cardiac Transport System for transportation of the allograft. This method of static hypothermic organ preservation allowed for a 330-minute total ischemic time, including 283 minutes of storage within the preservation system. The patient tolerated the procedure well and was discharged on postoperative day 10, with excellent graft function and no evidence of rejection 3 months postoperatively.

CONCLUSIONS

Though traditionally ischemic times of 240 minutes or less are recommended for cardiac allografts, we demonstrate, to our knowledge, the longest reported ischemic time of 330 minutes via use of a novel method of static hypothermia for organ preservation. The recipient had an excellent outcome postoperatively, demonstrating the potential for this new organ preservation system to expand the donor pool and improve access and use of heart transplantation.

Predicting post-operative right ventricular failure using video-based deep learning

Despite progressive improvements over the decades, the rich temporally resolved data in an echocardiogram remain underutilized. Human assessments reduce the complex patterns of cardiac wall motion, to a small list of measurements of heart function. All modern echocardiography artificial intelligence (AI) systems are similarly limited by design - automating measurements of the same reductionist metrics rather than utilizing the embedded wealth of data. This underutilization is most evident where clinical decision making is guided by subjective assessments of disease acuity. Predicting the likelihood of developing post-operative right ventricular failure (RV failure) in the setting of mechanical circulatory support is one such example. Here we describe a video AI system trained to predict post-operative RV failure using the full spatiotemporal density of information in pre-operative echocardiography. We achieve an AUC of 0.729, and show that this ML system significantly outperforms a team of human experts at the same task on independent evaluation.

Long-term survival in patients with post-LVAD right ventricular failure: multi-state modelling with competing outcomes of heart transplant

BACKGROUND

Multicenter data on long term survival following LVAD implantation that make use of contemporary definitions of RV failure are limited. Furthermore, traditional survival analyses censor patients who receive a bridge to heart transplant. Here we compare the outcomes of LVAD patients who develop post-operative RV failure accounting for the transitional probability of receiving an interim heart transplantation.

METHODS

We use a retrospective cohort of LVAD patients sourced from multiple high-volume centers based in the United States. Five- and ten-year survival accounting for transition probabilities of receiving a heart transplant were calculated using a multi-state Aalen Johansen survival model.

RESULTS

Of the 897 patients included in the study, 238 (26.5%) developed post-operative RV failure at index hospitalization. At 10 years the probability of death with post-op RV failure was 79.28% vs 61.70% in patients without (HR 2.10; 95% CI 1.72 - 2.57; p = < .001). Though not significant, patients with RV failure were less likely to be bridged to a heart transplant (HR 0.87, p = .4). Once transplanted the risk of death between both patient groups remained equivalent; the probability of death after a heart transplant was 3.97% in those with post-operative RV failure shortly after index LVAD implant, as compared to 14.71% in those without.

CONCLUSIONS AND RELEVANCE

Long-term durable mechanical circulatory support is associated with significantly higher mortality in patients who develop post-operative RV failure. Improving outcomes may necessitate expeditious bridge to heart transplant wherever appropriate, along with critical reassessment of organ allocation policies.

The Stanford experience of heart transplantation over five decades

AIMS 

Since 1968, heart transplantation has become the definitive treatment for patients with end-stage heart failure. We aimed to summarize our experience in heart transplantation at Stanford University since the first transplantation performed over 50 years ago.

METHODS AND RESULTS 

From 6 January 1968 to 30 November 2020, 2671 patients presented to Stanford University for heart transplantation, of which 1958 were adult heart transplantations. Descriptive analyses were performed for patients in 1968-95 (n = 639). Stabilized inverse probability weighting was applied to compare patients in 1996-2006 (n = 356) vs. 2007-19 (n = 515). Follow-up data were updated through 2020. The primary endpoint was all-cause mortality. Prior to weighting, recipients in 2007-19 vs. those in 1996-2006 were older and had heavier burden of chronic diseases. After the application of stabilized inverse probability weighting, the distance organ travelled increased from 84.2 ± 111.1 miles to 159.3 ± 169.9 miles from 1996-2006 to 2007-19. Total allograft ischaemia time also increased over time (199.6 ± 52.7 vs. 225.3 ± 50.0 min). Patients in 2007-19 showed superior survival than those in 1996-2006 with a median survival of 12.1 vs. 11.1 years.

CONCLUSION 

In this half-century retrospective descriptive study from one of the largest heart transplant programmes in the USA, long-term survival after heart transplantation has improved over time despite increased recipient and donor age, worsening comorbidities, increased technical complexity, and prolonged total allograft ischaemia time. Further investigation is warranted to delineate factors associated with the excellent outcomes observed in this study.

Patient-Specific Computational Fluid Dynamics Reveal Localized Flow Patterns Predictive of Post-Left Ventricular Assist Device Aortic Incompetence

BACKGROUND

Progressive aortic valve disease has remained a persistent cause of concern in patients with left ventricular assist devices. Aortic incompetence (AI) is a known predictor of both mortality and readmissions in this patient population and remains a challenging clinical problem.

METHODS

Ten left ventricular assist device patients with de novo aortic regurgitation and 19 control left ventricular assist device patients were identified. Three-dimensional models of patients' aortas were created from their computed tomography scans, following which large-scale patient-specific computational fluid dynamics simulations were performed with physiologically accurate boundary conditions using the SimVascular flow solver.

RESULTS

The spatial distributions of time-averaged wall shear stress and oscillatory shear index show no significant differences in the aortic root in patients with and without AI (mean difference, 0.67 dyne/cm2 [95% CI, -0.51 to 1.85]; P=0.23). Oscillatory shear index was also not significantly different between both groups of patients (mean difference, 0.03 [95% CI, -0.07 to 0.019]; P=0.22). The localized wall shear stress on the leaflet tips was significantly higher in the AI group than the non-AI group (1.62 versus 1.35 dyne/cm2; mean difference [95% CI, 0.15-0.39]; P<0.001), whereas oscillatory shear index was not significantly different between both groups (95% CI, -0.009 to 0.001; P=0.17).

CONCLUSIONS

Computational fluid dynamics serves a unique role in studying the hemodynamic features in left ventricular assist device patients where 4-dimensional magnetic resonance imaging remains unfeasible. Contrary to the widely accepted notions of highly disturbed flow, in this study, we demonstrate that the aortic root is a region of relatively stagnant flow. We further identified localized hemodynamic features in the aortic root that challenge our understanding of how AI develops in this patient population.

Three-Dimensional Multilayered Microstructure Using Needle Array Bioprinting System

Tissue engineering is an essential component of developing effective regenerative therapies. In this study, we introduce a promising method to create scaffold-free three-dimensional (3D) tissue engineered multilayered microstructures from cultured cells using the "3D tissue fabrication system" (Regenova^®; Cyfuse, Tokyo, Japan). This technique utilizes the adhesive nature of cells. When cells are cultured in nonadhesive wells, they tend to aggregate and form a spheroidal structure. The advantage of this approach is that cellular components can be mixed into one spheroid, thereby promoting the formation of extracellular matrices, such as collagen and elastin. This system enables one to create a predesigned 3D structure composed of cultured cells. We found that the advantages of this system to be (1) the length, size, and shape of the structure that were designable and highly reproducible because of the computer controlled robotics system, (2) the graftable structure could be created within a reasonable period (8 days), and (3) the constructed tissue did not contain any foreign material, which may avoid the potential issues of contamination, biotoxicity, and allergy. The utilization of this robotic system enabled the creation of a 3D multilayered microstructure made of cell-based spheres with a satisfactory mechanical properties and abundant extracellular matrix during a short period of time. These results suggest that this new technology will represent a promising, attractive, and practical strategy in the field of tissue engineering. Impact statement The utilization of the "three dimensional tissue fabrication system" enabled the creation of a three-dimensional (3D) multilayered microstructure made of cell-based spheres with a satisfactory mechanical properties and abundant extracellular matrix during a short period of time. These results suggest that this new technology will represent a promising, attractive, and practical strategy in the field of tissue engineering.

First lung and kidney multi-organ transplant following COVID-19 Infection

As the world responds to the global crisis of the COVID-19 pandemic an increasing number of patients are experiencing increased morbidity as a result of multi-organ involvement. Of these, a small proportion will progress to end-stage lung disease, become dialysis dependent, or both. Herein, we describe the first reported case of a successful combined lung and kidney transplantation in a patient with COVID-19. Lung transplantation, isolated or combined with other organs, is feasible and should be considered for select patients impacted by this deadly disease.

Current Status and Limitations of Myocardial Infarction Large Animal Models in Cardiovascular Translational Research

Establishing an appropriate disease model that mimics the complexities of human cardiovascular disease is critical for evaluating the clinical efficacy and translation success. The multifaceted and complex nature of human ischemic heart disease is difficult to recapitulate in animal models. This difficulty is often compounded by the methodological biases introduced in animal studies. Considerable variations across animal species, modifications made in surgical procedures, and inadequate randomization, sample size calculation, blinding, and heterogeneity of animal models used often produce preclinical cardiovascular research that looks promising but is irreproducible and not translatable. Moreover, many published papers are not transparent enough for other investigators to verify the feasibility of the studies and the therapeutics' efficacy. Unfortunately, successful translation of these innovative therapies in such a closed and biased research is difficult. This review discusses some challenges in current preclinical myocardial infarction research, focusing on the following three major inhibitors for its successful translation: Inappropriate disease model, frequent modifications to surgical procedures, and insufficient reporting transparency.

A Bioengineered Neuregulin-Hydrogel Therapy Reduces Scar Size and Enhances Post-Infarct Ventricular Contractility in an Ovine Large Animal Model

The clinical efficacy of neuregulin (NRG) in the treatment of heart failure is hindered by off-target exposure due to systemic delivery. We previously encapsulated neuregulin in a hydrogel (HG) for targeted and sustained myocardial delivery, demonstrating significant induction of cardiomyocyte proliferation and preservation of post-infarct cardiac function in a murine myocardial infarction (MI) model. Here, we performed a focused evaluation of our hydrogel-encapsulated neuregulin (NRG-HG) therapy’s potential to enhance cardiac function in an ovine large animal MI model. Adult male Dorset sheep (n = 21) underwent surgical induction of MI by coronary artery ligation. The sheep were randomized to receive an intramyocardial injection of saline, HG only, NRG only, or NRG-HG circumferentially around the infarct borderzone. Eight weeks after MI, closed-chest intracardiac pressure–volume hemodynamics were assessed, followed by heart explant for infarct size analysis. Compared to each of the control groups, NRG-HG significantly augmented left ventricular ejection fraction (p = 0.006) and contractility based on the slope of the end-systolic pressure–volume relationship (p = 0.006). NRG-HG also significantly reduced infarct scar size (p = 0.002). Overall, using a bioengineered hydrogel delivery system, a one-time dose of NRG delivered intramyocardially to the infarct borderzone at the time of MI in adult sheep significantly reduces scar size and enhances ventricular contractility at 8 weeks after MI.

Multidisciplinary approach utilizing early, intensive physical rehabilitation to accelerate recovery from veno-venous extracorporeal membrane oxygenation

This case demonstrates the benefits of our early, intensive physical rehabilitation intervention to prevent the natural sequelae occurring from prolonged bed rest. This minimizes neuromuscular weakness and optimizes strength, endurance and cardiorespiratory function, thus accelerating recovery from a long duration of femorally cannulated veno-venous extracorporeal membrane oxygenation.

Relation of Length of Survival After Orthotopic Heart Transplantation to Age of the Donor

We aim to evaluate the impact of donor age on the outcomes in orthotropic heart transplantation recipients. The United Network for Organ Sharing database was queried for adult patients (age; ≥60) underwent first-time orthotropic heart transplantation between 1987 and 2019 (n = 18,447). We stratified the cohort by donor age; 1,702 patients (9.2%) received a heart from a donor age of <17 years; 11,307 patients (61.3%) from a donor age of 17 ≥, < 40; 3,525 patients (19.1%) from a donor age of 40 ≥, < 50); and 1,913 patients (10.4%) from a donor age of ≥50. There was a significant difference in the survival likelihood (p < 0.0001) based on donor's age-based categorized cohort, however, the median survival was 10.5 years in the cohort in whom the donor was <17, 10.3 years in whom the donor was 17 ≥, < 40, 9.4 years in whom the donor was 40 ≥, < 50, and 9.0 years in whom the donor was ≥ 50. Additionally, there was no significant difference in the episode of acute rejection (p = 0.19) nor primary graft failure (p = 0.24). In conclusion, this study demonstrated that patients receiving hearts from the donor age of ≥50 years old showed slight inferior survival likelihood, but appeared to be equivalent median survival.