Outcomes of Adult Orthotopic Heart Transplantation With Extended Allograft Ischemic Time

Special Considerations for Advanced Heart Failure Surgeries: Durable Left Ventricular Devices and Heart Transplantation

Heart transplantation and durable left ventricular assist devices (LVADs) represent two definitive therapies for end-stage heart failure in the modern era. Despite technological advances, both treatment modalities continue to experience unique risks that impact surgical and perioperative decision-making. Here, we review special populations and factors that impact risk in LVAD and heart transplant surgery and examine critical decisions in the management of these patients. As both heart transplantation and the use of durable LVADs as destination therapy continue to increase, these considerations will be of increasing relevance in managing advanced heart failure and improving outcomes.

State of the art - Extracorporeal membrane oxygenation as a bridge to thoracic transplantation

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) has revolutionized the treatment of refractory cardiac and respiratory failure, and its use continues to increase, particularly in adults. However, ECMO-related morbidity and mortality remain high.

MAIN TEXT

In this review, we investigate and expand upon the current state of the art in thoracic transplant and extracorporeal life support (ELS). In particular, we examine recent increase in incidence of heart transplant in patients supported by ECMO; the potential changes in patient care and selection for transplant in the years prior to updated United Network for Organ Sharing (UNOS) organ allocation guidelines versus those in the years following, particularly where these guidelines pertain to ECMO; and the newly revived practice of heart-lung block transplants (HLT) and the prevalence and utility of ECMO support in patients listed for HLT.

CONCLUSIONS

Our findings highlight encouraging outcomes in patients bridged to transplant with ECMO, considerable changes in treatment surrounding the updated UNOS guidelines, and complex, diverse outcomes among different centers in their care for increasingly ill patients listed for thoracic transplant.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Risk factors for heart transplant survival with greater than 5 h of donor heart ischemic time

OBJECTIVE

Implantation of donor hearts with prolonged ischemic times is associated with worse survival. We sought to identify risk factors that modulate the effects of prolonged preservation.

METHODS

Retrospective review of the United Network for Organ Sharing database (2000-2018) to identify transplants with >5 (n = 1526) or ≤5 h (n = 35,733) of donor heart preservation. In transplanted hearts preserved for >5 h, Cox-proportional hazards identify modifiers for survival.

RESULTS

Compared to ≤5 h, transplanted patients with >5 h of preservation spent less time in status 1B (76 ± 160 vs. 85 ± 173 days, p = .027), more commonly had ischemic cardiomyopathy (42.3% vs. 38.3%, p = .002), and less commonly received a blood type O heart (45.4% vs. 50.8%, p < .001). Longer heart preservation time was associated with a higher incidence of postoperative stroke (4.5% vs. 2.5%, p < .001), and dialysis (16.4% vs. 10.6%, p < .001). Prolonged preservation was associated with a greater likelihood of death from primary graft dysfunction (2.8% vs. 1.5%, p < .001) but there was no difference in death from acute (2.0% vs. 1.7%, p = .402) or chronic rejection (2.0% vs. 1.9%, p = .618). In transplanted patients with >5 h of heart preservation, multivariable analysis identified greater mortality with ischemic cardiomyopathy etiology (hazard ratio [HR] = 1.36, p < 0.01), pre-transplant dialysis (HR = 1.84, p < .01), pre-transplant extracorporeal membrane oxygenation (ECMO, HR = 2.36, p = .09), and O blood type donor hearts (HR = 1.35, p < .01).

CONCLUSION

Preservation time >5 h is associated with worse survival. This mortality risk is further amplified by preoperative dialysis and ECMO, ischemic cardiomyopathy etiology, and use of O blood type donor hearts.

Extracorporeal membrane oxygenation bridge to heart transplant: Trends following the allocation change

BACKGROUND

This study compared outcomes of patients bridged with extracorporeal membrane oxygenation (ECMO) to orthotopic heart transplantation (OHT) following the recent heart allocation policy change.

METHODS

The United Network of Organ Sharing Registry (UNOS) database was queried to examine OHT patients between 2010 and 2020 that were bridged with ECMO. Waitlist outcomes and 1-year posttransplant survival were compared between patients waitlisted and/or transplanted before and after the heart allocation policy change. Secondary outcomes included posttransplant stroke, renal failure, and 1-year rejection.

RESULTS

A total of 285 waitlisted patients were included, 173 (60.7%) waitlisted under the old policy and 112 (39.3%) under the new policy. New policy patients were more likely to receive OHT (82.2% vs. 40.6%), and less likely to be removed from the waitlist due to death or clinical deterioration (15.0% vs. 41.3%; both p < .001). A total of 165 patients bridged from ECMO to OHT were analyzed, 72 (43.6%) transplanted during the old policy and 93 (56.3%) under the new. Median waitlist time was reduced under the new policy (4 days [interquartile range {IQR}: 2-6] vs. 47 days [IQR: 10-228]). Postoperative renal failure was higher in the new policy group (23% vs. 6%; p = .002), but rates of stroke and 1-year acute rejection were equivalent. One-year survival was lower the new policy but was not significant (79.8% vs. 90.3%; p = .3917).

CONCLUSIONS

The UNOS heart allocation policy change has resulted in decreased waitlist times and higher likelihood of transplant in patients supported with ECMO. Posttransplant 1-year survival has remained comparable although absolute rates are lower.

How Does Treating Chronic Hepatitis C Affect Individuals in Need of Organ Transplants in the United Kingdom?

OBJECTIVES

To estimate the impact of cures for chronic hepatitis C (CHC) infection on organ donation in the United Kingdom. Curing CHC infection reduces the need for liver transplants and enables cured individuals to donate organs of all types.

METHODS

We adapted a double-queuing model of organ allocation to estimate the effects of CHC infection cures on liver, lung, heart, and kidney transplants in the United Kingdom. We assumed that cured individuals would donate organs at similar rates as the general population and no longer require liver transplants because of CHC infection. We estimated how curing CHC infection influences waitlist lengths for each organ and the annual net present value to society on the basis of quality-adjusted life-years gained through additional transplants under opt-in and opt-out organ donation policies.

RESULTS

Curing CHC generates the most value for patients on the liver waitlist, because it increases the number of transplantable livers and reduces the need for transplants. Under the current opt-in policy, liver waitlist length falls by 24%, generating £34.3 million of annual net present value. Growth in the number of uninfected lungs, hearts, and kidneys generates an additional £19.2 million annually, with £18.7 million from kidneys. Implementing the opt-out policy, liver waitlist length would decrease by 75%, implying that treating CHC eliminates one-third of the excess liver waitlist due to an opt-in policy.

CONCLUSIONS

Treating CHC has large positive spillovers to uninfected individuals by reducing the need for liver transplants and allowing cured individuals to donate organs. These spillovers have not been included in traditional value assessments of CHC treatment.

How to obtain and maintain favorable results after heart transplantation: keys to success?

We compared survival in our heart recipients with survival rates reported by the International Society of Heart and Lung Transplantation (ISHLT) Registry. As recipient and donor characteristics are changing over time, we studied four different eras. In order to differentiate between short- and long-term survival, we analyzed both overall survival and survival at one year. Obviously, this exercise is only relevant when baseline donor and recipient characteristics are comparable, as these differences may affect the outcome in opposite directions. To overcome this potential bias as much as possible, we calculated the Index for Mortality Prediction After Cardiac Transplantation (IMPACT)-scores and the Donor Risk Index (DRI). Looking to our results, we found that our DRIs in the different eras are almost equal to those obtained from the United Network for Organ Sharing database in the very same eras. Our IMPACT-scores, on the other hand, seem higher than those reported by ISHLT. Survival after transplantation and conditional on 1-year survival was higher than the outcome reported by the ISHLT Registry. As our operation technique and post-transplant immunosuppressive schedule did not differ from most centers, we speculated on potential factors that might contribute to our positive results. Patient selection and a relatively short waiting time are important contributors to the overall survival benefit. Our centralized follow-up may also have played an important role. Finally, the indefinite compulsory health insurance coverage in our country and easy access to different screening programs might also have influenced our outcome in a positive way. We are well aware that with challenges like donor organ shortage, more and more patients on mechanical circulatory support (MCS) will affect outcomes in the future.

The impact of ischemic time on early rejection after pediatric heart transplant

Prolonged graft ischemia may be a risk factor for early rejection post-HTx, but this has not been well studied in children. Furthermore, factors moderating the association between IT and early rejection have not been investigated. From 2004 to 2012, pediatric HTx recipients (n = 2381) were identified from the UNOS database. A ROC curve determined the optimal IT discriminating patients by the presence of early rejection. Separate univariate analyses identified factors associated with: (i) early (prior to hospital discharge) rejection, and (ii) IT. A multivariable logistic regression assessed independent risk factors for early rejection. We included interaction terms to evaluate whether IT's independent risk effect on early rejection is moderated via interaction with associated factors found in univariate analysis. Longer IT was associated with an increased risk of early rejection. In multivariable analysis, IT > 3.1 hours was an independent risk factor for early rejection (AOR 1.44, P = .01). No interaction terms between IT and any associated factors were significant. Longer IT is an independent risk for early rejection in pediatric HTx recipients. Better understanding the association between IT and early rejection may identify interventions to mitigate this risk.

CPR, ECLS, BVAD and successful heart transplantation within 2 months: a single-centre case series in two young, high-urgency listed patients

INTRODUCTION

In times of organ shortage, death while on the heart waiting-list still represents a major problem. As a consequence, bridging to transplant as well as the decision when to escalate therapy play a very important role.

METHODS AND RESULTS

We report on two young patients with dilated cardiomyopathy and acute decompensation who were successfully bridged to heart transplantation with both left and temporary right ventricular assist devices in just 2 months.

CONCLUSIONS

As a permanent biventricular assist device (BVAD) would have definitely impaired the patients' outcome after HTX, we decided to implant an LVAD with a temporary RVAD. In our opinion, this represents a suitable strategy to reduce mortality in HU-listed patients with acute deterioration of cardiac pump function and should be further evaluated in future studies.

Transport of Human Organs in Italy: Location, Time, and Performances

INTRODUCTION

The outcome of transplantation activities depends on a variety of unpredictable factors. Up-to-date criteria on organ allocation foresee an efficient transport chain along with compliant performance parameters.

METHODS AND OBJECTIVES

The Centro Nazionale Trapianti and the Department of Civil, Chemical, Environmental, and Materials Engineering of the University of Bologna (respectively, CNT and DICAM) have been updating a national database of organ transplantation activities to investigate performance parameters and the main causes of disruption.

RESULTS

Between June 2015 and July 2016, 617 of 1061 organs have been shipped by air (making for 486 flight events), of which 407 were accompanied by medical equipment. Origin/destination and distance matrixes have been drawn for both road and air transport. Each airport node is ranked based on the n° of organs ingoing/outgoing and each route link on its frequency. Performance parameters such as average speed, distance covered, and time have been computed and compared with each organ's cold ischemia time (CIT). Average distance frontiers are rather homogeneous, but much effort is necessary to reduce the number of events performed with approximately 90% or more of CIT spent.

CONCLUSIONS

The monitoring of organ transplantation activities' performance is a standalone action within Europe to support strategic policies to optimize the system. Thus, a clearer awareness on performances and issues related to organ transport has been made possible: analyses show that the higher uncertainty associated with total time of displacement by air is due to the steps which take place by road (length and paths must be optimized) and lung transports generally perform weaker than heart transports due to longer average distances travelled and smaller average speeds, often resulting in a total displacement time greater than 90% of CIT.

Association of the Number of HLA-DR Mismatches With Early Post-transplant Acute Cellular Rejection Among Heart Transplantation Recipients: A Cohort Study in Japanese Population

BACKGROUND

Although many risk factors are reported about graft rejection after heart transplantation (HTx), the effect of HLA mismatch (MM) still remains unknown, especially in the Japanese population. The aim of the present study was to investigate the influence of HLA MM on graft rejection among HTx recipients in Japan.

METHODS

We retrospectively investigated the association of the number of HLA MM including class I (A, B) and class II (DR) (for each locus MM: 0 to 2, total MM: 0 to 6) and the incidence of moderate to severe acute cellular rejection (ACR) confirmed by endomyocardial biopsy (International Society for Heart and Lung Transplantation grade ≥ 3A/2R) within 1 year after HTx.

RESULTS

Between 2007 and 2014, we had 49 HTx cases in our institute. After excluding those with insufficient data and positive donor-specific antigen, finally 35 patients were enrolled. Moderate to severe ACR was observed in 16 (45.7%) patients. The number of HLA-DR MM was significantly associated with the development of ACR (ACR+: 1.50 ± 0.63, ACR-: 1.11 ± 0.46, P = .029). From univariate analysis, DR MM = 2 was the only independent risk factor for ACR episodes (P = .017). The frequency of ACR within 1 year was significantly higher in those with DR MM = 2 (DR MM = 0 to 1: 0.3 ± 0.47, DR MM = 2: 1.17 ± 1.34 times, P = .007).

CONCLUSIONS

The number of HLA-DR MMs was associated with the development and recurrence of ACR episodes among HTx recipients within 1 year after transplantation in Japanese population.

Comparison of early versus delayed timing of left ventricular assist device implantation as a bridge-to-transplantation: An analysis of the UNOS dataset

BACKGROUND

Placement of left ventricular assist devices (LVAD) as a bridge-to-heart transplantation (HTx) has rapidly expanded due to organ donor shortage. However, the timing of LVAD implantation is variable and it remains unclear if earlier implantation improves survival.

METHODS

We analyzed 14,187 adult candidates from the United Network of Organ Sharing database. Patients were classified by 3 treatment strategies including patients medically treated alone (MED, n=11,009), patients on LVAD support at listing (Early-LVAD, n=1588) and patients undergoing LVAD placement while awaiting HTx (Delayed-LVAD, n=1590). Likelihood of HTx and event-free survival were assessed in patients subcategorized by clinical strategies and UNOS status at listing.

RESULTS

The device support strategy, despite the timing of placement, was not associated with increased likelihood of HTx compared to MED group. However, both LVAD implantation strategies showed better survival compared to MED group (Early-LVAD: HR 0.811 and 0.633, 95% CI 0.668-0.984 and 0.507-0.789, for 1A and 1B; p=0.034 and p<0.001, Delayed-LVAD: HR 0.553 and 0.696, 95% CI 0.415-0.736 and 0.571-0.847, for 1A and 1B; both p<0.001, respectively). Furthermore, there was no significant difference in survival between these LVAD implantation strategies in patients listed as 1B (p=0.500), although Early-LVAD implantation showed worse survival in patients listed as 1A (HR 1.467, 95% CI 1.076-2.000; p=0.015).

CONCLUSION

LVAD support strategies offer a safe bridge-to-HTx. Those candidates who receive urgent upfront LVAD implantation for HTx, and improve to 1B status, would achieve competitive survival with those who receive elective LVAD implantation.

Ex-vivo perfusion of donor hearts for human heart transplantation (PROCEED II): a prospective, open-label, multicentre, randomised non-inferiority trial

BACKGROUND

The Organ Care System is the only clinical platform for ex-vivo perfusion of human donor hearts. The system preserves the donor heart in a warm beating state during transport from the donor hospital to the recipient hospital. We aimed to assess the clinical outcomes of the Organ Care System compared with standard cold storage of human donor hearts for transplantation.

METHODS

We did this prospective, open-label, multicentre, randomised non-inferiority trial at ten heart-transplant centres in the USA and Europe. Eligible heart-transplant candidates (aged >18 years) were randomly assigned (1:1) to receive donor hearts preserved with either the Organ Care System or standard cold storage. Participants, investigators, and medical staff were not masked to group assignment. The primary endpoint was 30 day patient and graft survival, with a 10% non-inferiority margin. We did analyses in the intention-to-treat, as-treated, and per-protocol populations. This trial is registered with ClinicalTrials.gov, number NCT00855712.

FINDINGS

Between June 29, 2010, and Sept 16, 2013, we randomly assigned 130 patients to the Organ Care System group (n=67) or the standard cold storage group (n=63). 30 day patient and graft survival rates were 94% (n=63) in the Organ Care System group and 97% (n=61) in the standard cold storage group (difference 2·8%, one-sided 95% upper confidence bound 8·8; p=0·45). Eight (13%) patients in the Organ Care System group and nine (14%) patients in the standard cold storage group had cardiac-related serious adverse events.

INTERPRETATION

Heart transplantation using donor hearts adequately preserved with the Organ Care System or with standard cold storage yield similar short-term clinical outcomes. The metabolic assessment capability of the Organ Care System needs further study.

FUNDING

TransMedics.