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

Optimal Pre-Transplant Duration with HeartMate III Left Ventricular Assist Device: A Contemporary Analysis

BACKGROUND

This study evaluates the impact of pretransplant HeartMate III (HM3) left ventricular assist device (LVAD) support duration on post-transplant survival in a contemporary cohort.

METHODS

A retrospective review of the United Network for Organ Sharing database was conducted for adult heart transplant recipients from January 2019 to December 2023 who were bridged with an HM3 LVAD. We utilized a restricted cubic spline fitted to a Cox proportional hazards model to stratify patients into duration groups based on risk inflection points (<1 year, 1-2 years, and >2 years), and outcomes were compared between and across groups.

RESULTS

Among 1,996 patients, 35.2%(n=702), 32.2%(n=642), and 32.7%(n=652) had support durations of <1 year, 1-2 years, and >2 years, respectively. Median support duration was 518 days [IQR: 289-864]. Postoperative rates of stroke and acute rejection did not vary across groups (p>0.05), however rates of postoperative dialysis significantly increased with increasing support time (p>0.001). One-year survival was significantly higher for patients bridged <1 year (90.7% [95%CI: 88.5-93.0]) compared to those bridged >2 years (84.3% [95% CI: 81.4-87.4], p<0.001) but not for those bridged 1-2 years (89.0% [95% CI: 86.6-91.6], p=0.300). In multivariable analysis, patients supported 1-2 years (HR: 1.34 [1.01-1.79], p=0.045) and >2 years (HR: 1.77 [1.32-2.38], p<0.001) had a higher hazard of post-transplant mortality than those bridged <1 year.

CONCLUSIONS

While the HM3 enables extended bridging to transplant, durations longer than 2 years of support are linked to worse post-transplant survival.

Donor heart allocation systems in Europe. A scientific statement of the Heart Failure Association of the ESC

Heart transplantation remains the gold standard for treatment of most patients with advanced heart failure (HF), but despite improvements of organ recovery and utilization, donor heart scarcity remains a critically limiting factor. Detailed heart allocation systems (HASs) are in place to ensure use of organs for appropriate candidates, In Europe multiple, different HASs have evolved in different countries or communities of collaborating countries, like Eurotransplant or Scandiatransplant. In this scientific statement, we review the generic ethical and practical principles underlying allocation principles and examine and describe different European HASs with the purpose of discussing impact of outcomes for patients with advanced HF. It is shown that European HASs differ significantly with respect to which patients are prioritized and the methods by which the prioritization is performed. It is argued that the most commonly used parameter to describe success of a HAS, namely 1-year survival after heart transplantation, is a poor metric of HAS performance. The impact of HASs should be evaluated by several measures such as survival from listing, time to transplantation, the characteristics of patients undergoing heart transplantation, and over a longer time interval to understand the balance of early and late post-transplant risks and benefit. Mapping European HASs is a step towards understanding these factors and further research should determine the optimal HAS in a given HF population at a given time.

National Organ Procurement and Transplant Network Heart Allocation Policy: 6 Years Later

In 2014, the Organ Procurement and Transplant Network began reappraisal of the United States heart transplant allocation policy. Driven by ongoing discordance between organ supply and demand, high waitlist mortality, and increasing exception requests, the Thoracic Committee radically redesigned the priority scheme and drafted a 6-tiered algorithm, included durable device complications into policy, expanded broader sharing, and increased the number of mandatory listing variables to develop a future heart allocation score. This became the 2018 New Heart Allocation Policy. Changes in allocation priority have resulted in a significant increase in the use of temporary mechanical circulatory support in waitlisted candidates with a concomitant decrease in the number of patients bridged to transplanted with durable left ventricular assist device support. The number of exception requests continues to increase, particularly for patients listed status 2 and for multiorgan transplants. Importantly, fewer patients are being delisted for clinical improvement, suggesting missed opportunities for recovery. The current review will critically evaluate the 2018 heart allocation policy 6 years later, briefly focusing on the history of heart allocation in the United States, the current and evolving algorithms for candidate prioritization including continuous distribution, the impact of technology and innovation on transplant rates and future policy development, and the ongoing regulatory oversight and governance changes in the Organ Procurement and Transplant Network.

Durable left ventricular assist devices: a contemporary review of their benefits and drawbacks

INTRODUCTION

Heart transplantation, the gold standard for end-stage cardiomyopathy, is hindered by donor shortages and clinical deterioration. Left ventricular assist devices (LVADs) have emerged as crucial alternatives, stabilizing hemodynamics, reversing end-organ damage, and enabling patient discharge. Significant engineering advancements and iterative improvements have since produced devices capable of rivaling heart transplantation in early survival potential. This review serves to provide an overview of LVAD technology, an understanding of current device limitations, and preview new technologies being developed to address them.

AREAS COVERED

This manuscript reviews the evolution of LVAD technology, discussing its benefits, drawbacks, and contemporary outcomes. It will detail the progression, current state, and future directions of LVAD technology, emphasizing its pivotal role in managing advanced heart failure.

EXPERT OPINION

The modern day LVAD has significantly extended the lifespan of patients with end-stage heart failure. However, adverse events remain abound and will be the focus of the next generation of devices. A burgeoning pipline of new technologies abound and preview the possibilities of a sustainable solution to a devastating disease.

Predictive Accuracy of HeartMate 3 Risk Score After the Heart Transplant Allocation Change

The HeartMate 3 risk score (HM3RS) was developed from the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy with HeartMate 3 (MOMENTUM 3) clinical trial to predict 1 and 2 year mortality after left ventricular assist device implantation. However, it has not been validated in a real-world population, especially after the heart transplant allocation system change on October 18, 2018. In this multicenter retrospective analysis, we found that HM3RS did not predict 1 and 2 year outcomes in the contemporary era, highlighting the need to revise this risk prediction tool in the real-world setting.

Changes in Donor Utilization and Outcomes for Patients Bridged With Durable Left Ventricular Assist Device

We studied the impact of the 2018 heart allocation policy change on donor characteristics and posttransplant outcomes of left ventricular assist device (LVAD)-bridged heart transplant (HT) recipients. Left ventricular assist device-bridged adult HT recipients from October 2014 to October 2022 in the United Network for Organ Sharing database were categorized into old allocation policy (OAP) and new allocation policy (NAP) cohorts. Baseline characteristics, posttransplant outcomes, and subgroup analyses of unstable and stable LVAD-bridged recipients were assessed. The study included 7,384 HT recipients; 4,345 (58.8%) were transplanted in the OAP era and 3,039 (41.2%) in the NAP era. Old allocation policy recipients were most frequently status 1A at transplantation (71.1%), whereas NAP recipients were most frequently status 3 (40.0%), and status 4 (31.9%). Median donor sequence number (DSN) was higher in the NAP versus OAP era (9 vs. 3, p < 0.001). On multivariable analysis, NAP recipients had 20% higher 1 year mortality compared to OAP (adjusted hazard ratio [aHR] = 1.20 [95% confidence interval {CI}: 1.04-1.40], p = 0.01). Status 1 or 2 recipients had 28% higher 1 year mortality compared to status 1A (aHR = 1.28 [95% CI: 1.01-1.63], p = 0.04). Status 1 and 2 LVAD-supported recipients had higher mortality following the 2018 allocation change, indicating the need for closer surveillance of LVAD-bridged patients who may decompensate on the waitlist.

Impact of Heart Transplant Allocation Change on Waitlist Mortality and Posttransplant Mortality in Patients With Left Ventricular Assist Devices

BACKGROUND

In October 2018, the US heart transplant (HT) allocation system was revised giving patients with left ventricular assist device (LVAD) intermediate priority status. Few studies have examined the impact of this policy change on outcomes among patients with LVAD. We sought to determine how the allocation change impacted waitlist and posttransplant mortality in patients with LVAD.

METHODS

We retrospectively assessed the United Network for Organ Sharing registry for patients with LVAD who were listed for or underwent HT between October 2016 and October 2021. We evaluated waitlist mortality using competing risks analysis and a multivariable Fine-Gray model, and posttransplant mortality using Kaplan-Meier survival analysis and a multivariate proportional hazards model.

RESULTS

We analyzed data from 3835 patients with LVAD listed for HT and 3486 patients with LVAD who underwent HT during the study period. Listing for HT preallocation change was significantly associated with an increased risk of waitlist mortality (Gray P=0.0058) compared with postallocation change. After adjustment for covariates, mortality differences by listing era were attenuated, but LVAD brand was significantly associated with waitlist mortality (HM3 versus HMII; hazard ratio, 0.38 [95% CI, 0.21-0.69]; P=0.002; HVAD versus HMII; hazard ratio, 0.79 [95% CI, 0.48-1.30]; P=0.36; overall P=0.004). In contrast, HT postallocation change was associated with increased posttransplant mortality (log-rank P=0.0172) compared with preallocation change. In a multivariable analysis, the association with posttransplant mortality between transplant eras was attenuated, but ischemic time (hazard ratio, 1.16 [95% CI, 1.07-1.26]; P<0.001) and status at time of HT (Status 1-3 versus 4; hazard ratio, 1.29 [95% CI, 1.04-1.61]; P=0.02) were significantly associated with posttransplant mortality.

CONCLUSIONS

Among patients with LVAD, lower waitlist mortality postallocation change was likely driven by improved LVAD technology. Higher posttransplant mortality following the allocation change was largely attributable to longer ischemic times and patient acuity.

Risk and Reward: Nationwide Analysis of Cardiac Transplant Center Variation in Organ Travel Distance and the Effects on Outcomes

BACKGROUND

The 2018 UNOS allocation policy change deprioritized geographic boundaries to organ distribution, and the effects of this change have been widespread. The aim of this investigation was to analyze changes in donor transplant center distance for organ travel and corresponding outcomes before and after the allocation policy change.

METHODS

The UNOS database was utilized to identify all adult patients waitlisted for heart transplants from 2016 to 2021. Transplant centers were grouped by average donor heart travel distance based on whether they received more or less than 50% of organs from >250 miles away. Descriptive statistics were provided for waitlisted and transplanted patients. Regression analyses modeled waitlist mortality, incidence of transplant, overall survival, and graft survival.

RESULTS

Centers with a longer average travel distance had a higher mean annual transplant volume with a reduction in total days on a waitlist (86.6 vs. 149.2 days), an increased cold ischemic time (3.6 vs. 3.2 h), with no significant difference in post-transplant overall survival or graft survival.

CONCLUSIONS

The benefits of reducing waitlist time while preserving post-transplant outcomes extend broadly. The trends observed in this investigation will be useful as we revise organ transplant policy in the era of new organ procurement and preservation techniques.

Three-Year Left Ventricular Assist Device Outcomes and Strategy After Heart Transplant Allocation Score Change

The United Network for Organ Sharing (UNOS) adopted new criteria for the heart allocation score on October 18, 2018 to reflect the changing trends of candidates' mortality while awaiting transplant. We examined the impact of these policy changes on rates of left ventricular assist device (LVAD) implantation and outcomes after transplant from a relatively newer UNOS database. The UNOS registry was used to identify first-time adult heart recipients with LVAD at listing or transplant who underwent transplantation between January 1, 2016 and March 10, 2020. Survival data were collected through March 30, 2023. Those listed before October 18, 2018 but transplanted after were excluded. Patients were divided into before or after change groups. Demographics and clinical parameters were compared. Survival was analyzed with Kaplan-Meier curves and log-rank tests. A p <0.05 was considered significant. We identified 4,387 heart recipients with LVAD in the before (n = 3,606) and after (n = 781) score change eras. The after group had a lower rate of LVAD implantation while listed than the before group (20.4% vs 34.9%, p <0.0001), and were more likely to be female (25.1% vs 20.2%, p = 0.002); in both groups, most recipients (62.8%) were white. There was significantly farther distance from the donor hospital to transplant center in the after group (264.4 NM vs 144.2 NM, p <0.0001) and decreased waitlist days (84.9 ± 105.1 vs 369.2 ± 459.5, p <0.0001). Recipients in the after group were more likely to use extracorporeal membrane oxygenation (3.7% vs 0.5%, p <0.0001) and intravenous inotropes (19.1% vs 7.5%, p <0.0001) and receive a Centers for Disease Control and Prevention increased risk donor organ (37.9% vs 30.5%, p <0.0001). Survival at 3 years was comparable between the 2 groups. The allocation score change in 2018 yielded considerable changes in mechanical circulatory support device implantation strategy and outcomes. The rate of LVAD implantation decreased with increased utilization of temporary mechanical circulatory support devices.

Outcomes of Impella 5.0 and 5.5 for cardiogenic shock: A single-center 137 patient experience

BACKGROUND

This study evaluated the outcomes of patients with cardiogenic shock (CS) supported with Impella 5.0 or 5.5 and identified risk factors for in-hospital mortality.

METHODS

Adults with CS who were supported with Impella 5.0 or 5.5 at a single institution were included. Patients were stratified into three groups according to their CS etiology: (1) acute myocardial infarction (AMI), (2) acute decompensated heart failure (ADHF), and (3) postcardiotomy (PC). The primary outcome was survival, and secondary outcomes included adverse events during Impella support and length of stay. Multivariable logistic regression was performed to identify risk factors for in-hospital mortality.

RESULTS

One hundred and thirty-seven patients with CS secondary to AMI (n = 47), ADHF (n = 86), and PC (n = 4) were included. The ADHF group had the highest survival rates at all time points. Acute kidney injury (AKI) was the most common complication during Impella support in all 3 groups. Increased rates of AKI and de novo renal replacement therapy were observed in the PC group, and the AMI group experienced a higher incidence of bleeding requiring transfusion. Multivariable analysis demonstrated diabetes mellitus, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine were independent predictors of in-hospital mortality, but the etiology of CS did not impact mortality.

CONCLUSIONS

This study demonstrates that Impella 5.0 and 5.5 provide effective mechanical support for patients with CS with favorable outcomes, with nearly two-thirds of patients alive at 180 days. Diabetes, elevated pre-insertion serum lactate, and elevated pre-insertion serum creatinine are strong risk factors for in-hospital mortality.

Donation after circulatory death improves probability of heart transplantation in waitlisted candidates and results in post-transplant outcomes similar to those achieved with brain-dead donors

OBJECTIVE

To quantitate the impact of heart donation after circulatory death (DCD) donor utilization on both waitlist and post-transplant outcomes in the United States.

METHODS

The United Network for Organ Sharing database was queried to identify all adult waitlisted and transplanted candidates between October 18, 2018, and December 31, 2022. Waitlisted candidates were stratified according to whether they had been approved for donation after brain death (DBD) offers only or also approved for DCD offers. The cumulative incidence of transplantation was compared between the 2 cohorts. In a post-transplant analysis, 1-year post-transplant survival was compared between unmatched and propensity-score-matched cohorts of DBD and DCD recipients.

RESULTS

A total of 14,803 candidates were waitlisted, including 12,287 approved for DBD donors only and 2516 approved for DCD donors. Overall, DCD approval was associated with an increased sub-hazard ratio (HR) for transplantation and a lower sub-HR for delisting owing to death/deterioration after risk adjustment. In a subgroup analysis, candidates with blood type B and status 4 designation received the greatest benefit from DCD approval. A total of 12,238 recipients underwent transplantation, 11,636 with DBD hearts and 602 with DCD hearts. Median waitlist times were significantly shorter for status 3 and status 4 recipients receiving DCD hearts. One-year post-transplant survival was comparable between unmatched and propensity score-matched cohorts of DBD and DCD recipients.

CONCLUSIONS

The use of DCD hearts confers a higher probability of transplantation and a lower incidence of death/deterioration while on the waitlist, particularly among certain subpopulations such as status 4 candidates. Importantly, the use of DCD donors results in similar post-transplant survival as DBD donors.