Donor Age More Than 20 Years Greater Than Recipient Age Is Associated With Worse 5 Year Survival in Young Adult Heart Transplantation.

Prior studies indicate donor age-recipient age (DA-RA) difference may be of prognostic value in adolescents, although not adults. We aim to analyze the relationship between DA-RA difference and long-term survival of young adult heart transplantation (HTx) recipients. First-time, single-organ HTx recipients aged 18-30 who underwent HTx between 2010 and 2020 were analyzed from the United Network for Organ Sharing (UNOS) registry. Four cohorts were created based on DA-RA difference. The primary outcome was 5 year post-HTx survival. Secondary outcome was post-HTx complications. One thousand eight hundred three donor-recipient pairs were divided into four groups: DA-RA < 0, 0 ≤ DA-RA < 10, 10 ≤ DA-RA < 20, and DA-RA ≥ 20 with 682 (37.8%), 651 (36.1%), 356 (19.7%), 114 (6.3%) pairs in each cohort, respectively. The estimated 5 year survival of the DA-RA ≥ 20 cohort was 66.5% compared to the other three groups at ~75%. After adjustment, DA-RA ≥ 20 was independently associated with worse survival compared to DA-RA < 0 (adjusted hazard ratio [HR] = 1.55; 95% confidence interval [CI] = 1.06-2.27; log-rank p = 0.008). There was no significant difference in complication incidence across cohorts. Among young adults, accepting a donor heart more than 20 years older than the recipient was associated with worse 5 year survival. We did not detect a significant difference up to 20 years. This information may help guide appropriate donor selection in the young adult population.

The Impact of Pre-Heart Transplantation Blood Transfusion Varies Based on Recipient MELD-XI Score.

Prior studies reveal adverse effects of transfusion on cardiac surgery, but little is known of transfusion impact on heart transplantation. First-time, single-organ adult heart transplant recipients between January 1, 2010, and December 31, 2020, were included, stratified above or below a model for end-stage liver disease excluding international normalized ratio (MELD-XI) score of 9.4, and propensity score matched to their nearest neighbor. A 90 day landmark analysis within each cohort was also performed. Unadjusted analysis showed transfusion recipients, MELD-XI ≥9.4, were more likely to experience post-heart transplantation mortality (Hazard Ratio (HR), 1.352 [95% Confidence Interval (CI), 1.239-1.477], p < 0.001), persisting after adjustment for potential confounders (adjusted HR, 1.211 [95% CI, 1.100-1.335], p < 0.001) and after propensity-score matching (HR, 1.174 [95% CI, 1.045-1.319], p = 0.007). Post-transplant length of stay was longer (25.9 vs. 23.2 days, p < 0.001). Post-transplant dialysis was more common (18.7 vs. 15.9%, p = 0.009). There was no survival difference on 90 day landmarked analysis (p = 0.108). With MELD-XI <9.4, there was slight survival detriment among transfusion recipients on univariable analysis (HR, 1.111 [95% CI, 1.001-1.234], p = 0.049) but not on multivariable analysis (adjusted HR, 1.061 [95% CI, 0.952-1.181], p = 0.285). There was similar survival after propensity-score matching (HR, 1.032 [95% CI, 0.903-1.180], p = 0.642) and on landmark analysis (p = 0.581). Ultimately, transfusion was associated with worse post-heart transplantation outcomes among recipients with a MELD-XI ≥9.4.

Does Preoperative Weight Loss Affect Outcomes After Major Liver Resection? Analysis of a National Database.

Introduction: The association between unintentional weight loss (WL) and outcomes after major hepatectomy for malignancy remains unclear.Methods: This retrospective cohort study reviewed the 2014-2019 NSQIP database of all patients who underwent major liver resections. The patients were categorized into two groups based on their history of weight loss. The primary outcome measure was the 30-day mortality. The secondary outcome was 30-day in-hospital complications.Results: In total, 384 patients had a history of preoperative weight loss. Preoperative WL was an independent predictor of septic shock (OR, 2.44; CI: 1.61, 3.69), bile leak (OR: 1.96; CI: 1.51, 2.55), and grade C liver failure (OR: 2.57; CI: 1.64, 4.01). However, preoperative WL was not a significant predictor of perioperative mortality (OR: 1.38; CI: 0.82, 2.32).Conclusion: The study found higher morbidity rates in patients undergoing liver resection with a history of weight loss. Further validation with prospective weight monitoring is needed to validate as a prognostic marker in patients undergoing hepatectomy. In addition, weight changes can help guide multidisciplinary decision-making in treating patients undergoing hepatectomy.

Blood type O heart transplant candidates have longer waitlist time and higher delisting under the new allocation system.

OBJECTIVE: Prior studies have examined the effect of blood type on heart transplantation (HTx) waitlist outcomes in cohorts through 2015. We aim to analyze the effect of blood type on contemporary waitlist outcomes with a new allocation system focus. METHODS: Adults listed for HTx between April 2015 and December 2020 were included. Survival to HTx and waitlist death/deterioration was compared between type O and non-type O candidates using competing risks regression. Donor/recipient ABO compatibility trends were further investigated. RESULTS: Candidates with blood type O (n = 7509) underwent HTx less frequently than candidates with blood type other than type O (n = 9699) (subhazard ratio [sHR], 0.56; 95% CI, 0.53-0.58) with higher rates of waitlist death/deterioration (sHR, 1.18; 95% CI, 1.04-1.34). Subgroup analyses demonstrated persistence of this trend under the new donor heart allocation system (HTx: sHR, 0.58; 95% CI, 0.54-0.62; death/clinical deterioration: sHR, 1.27; 95% CI, 1.02-1.60), especially among those listed at high status (1, 2, or 3) (HTx: sHR, 0.69; 95% CI, 0.63-0.75; death/deterioration: sHR, 1.61; 95% CI, 1.16-2.22). Among those listed at status 3, waitlist death/deterioration was modified by presence of a durable left ventricular assist device (left ventricular assist device: sHR, 1.57; 95% CI, 0.58-4.29; no left ventricular assist device: sHR, 3.79; 95% CI, 1.28-11.2). Type O donor heart allocation to secondary ABO candidates increased in the new system (14.5% vs 12.0%; P < .01); post-HTx survival remained comparable between recipients with blood type O and non-type O (log-rank P = .07). CONCLUSIONS: Further logistical considerations are warranted to minimize allocation inequity regarding blood type under the new allocation system.

Association Between Preoperative Angioembolization and Bleeding Complications in Patients With Benign Liver Tumors: Analysis of a National Database.

INTRODUCTION: The role of angioembolization (AE) in patients with benign liver diseases is an area of active research. This study aims to assess any difference in liver resection outcomes in patients with benign tumors dependent on utilization of preoperative AE. METHODS: A retrospective cohort study of patients undergoing elective liver resections for benign liver tumors was performed using the National Surgical Quality Improvement Program database (2014-2019). Only tumors of 5 cm in size or more were included in the analysis. We categorized the patients based on preoperative AE (AE + versus AE -). The primary outcome measured included bleeding complications within 72 h. The secondary outcomes were to determine predictors of bleeding. RESULTS: After propensity score matching, there were 103 patients in both groups. There was no difference in intraoperative or postoperative blood transfusions within 72 h of surgery (14.6% versus 12.6%; P = 0.68), reoperation (1.9% versus 1.9%; P = 1), or mortality (1.0% versus 0.0%; P = 1) between the two groups. Multivariate regression analysis revealed an open surgical approach (odds ratio [OR]: 4.59 confidence interval [CI]: 2.94-7.16), use of Pringle maneuver (OR: 1.7, CI: 1.26-2.310), preoperative anemia (OR: 2.79, CI: 2.05-3.80), and preoperative hypoalbuminemia (OR: 1.53 [1.14-2.05]) were associated with the need for intraoperative or postoperative blood transfusions within 72 h of surgery. CONCLUSIONS: Preoperative AE was not associated with reducing intraoperative or postoperative bleeding complications or blood transfusions within 72 h after surgery.

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

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

Heart Transplant Waitlist Outcomes and Wait Time by Center Volume in the Pre-2018 Allocation Change Era.

Although the transplant outcomes of centers are heavily monitored and compared, with a particular link between posttransplant outcomes and center volume demonstrated, little data exist comparing waitlist outcomes. Here, we explored waitlist outcomes by transplant center volume. We performed a retrospective analysis of adults listed for primary heart transplantation (HTx) from 2008 to 2018 using the United Network for Organ Sharing database. Transplant centers were split into low (<10 HTx/year), medium (10-30 HTx/year), and high (>30 HTx/year) volume, and waitlist outcomes were compared. Of the 35,190 patients included in our study, 23,726 (67.4%) underwent HTx, 4,915 (14.0%) died or deteriorated before receiving HTx, 1,356 (3.9%) were delisted due to recovery, and 1,336 (3.8%) underwent left ventricular assist device (LVAD) implantation. High-volume centers had higher rates of survival to transplant (71.3% vs. 60.6% for low-volume centers and 64.9% for medium-volume centers), and low rates of death or deterioration (12.6% vs. 14.6% for low-volume centers and 15.1% for medium-volume centers). Listing at a low-volume center was independently associated with death or delisting before HTx (HR 1.18, p = 0.007), whereas listing at a high-volume center (HR 0.86; p < 0.001) and prelisting LVAD (HR 0.67, p < 0.001) were protective. Death or delisting before HTx was lowest for patients listed in higher volume centers.

Impella 5.5 Support Beyond 50 Days as Bridge to Heart Transplant in End-Stage Heart Failure Patients.

Prolonged mechanical circulatory support (MCS) for severe left ventricular dysfunction in cardiogenic shock as a bridge to heart transplantation (HTx) generally requires a surgical procedure. Typically, a surgically implanted temporary extracorporeal left ventricular assist device (LVAD) is chosen because of superior flow and durability compared with a percutaneously delivered endovascular LVAD (pVAD). However, compared with its predecessors, the Impella 5.5 trans-valvular pVAD provides higher hemodynamic support and features improved durability. Here, we present four successful cases with prolonged Impella 5.5 support as a bridge to HTx, with a mean support duration of 70 days (maximum 83 days). These cases highlight several potential benefits of Impella 5.5. The minimally invasive implantation procedure of the device reduces bleeding, decreases the postoperative recovery period, and enables early patient ambulation to reduce physical deconditioning before HTx surgery. Furthermore, Impella 5.5 adequately unloads the left ventricle and provides hemodynamic support to maintain end-organ function to further optimize hemodynamics before HTx. The evolution of Impella 5.5 technology may provide an alternative bridging strategy to traditional surgically implanted temporary MCS in select cases.

Total ventricular mass oversizing +50% or greater was a predictor of worse 1-year survival after heart transplantation.

OBJECTIVES: Current donor-recipient size matching guidelines rely primarily on body weight, with no specified oversizing cutoff values. Recent literature has explored predicted total ventricular mass matching over body weight matching. We aim to explore the impact of total ventricular mass oversizing on heart transplant outcomes. METHODS: The United Network for Organ Sharing database was queried for adults who underwent primary heart transplant from 1997 to 2017. By using validated equations, donor-recipient total ventricular mass mismatch was calculated. Donor-recipient pairs were divided into 3 groups by total ventricular mass mismatch. Post-heart transplant 1-year survival was analyzed using the Kaplan-Meier method and Cox proportional hazards models. We also investigated post-heart transplant complications, independent predictors for mortality, donor-recipient sex mismatch, and donor-recipient body habitus in total ventricular mass mismatch greater than +50%. RESULTS: A total of 34,455 donor-recipient pairs were included. Fractional polynomial regression demonstrated increased the risk of mortality with higher total ventricular mass mismatch. Total ventricular mass mismatch of +48.3% maximized the Youden Index. Donor-recipient pairs were subsequently grouped by total ventricular mass mismatch as -20% to +30%, +30% to +50%, and greater than +50%. Total ventricular mass mismatch greater than +50% was an independent risk factor for 1-year mortality (hazard ratio, 1.40, P = .004) and was associated with increased postoperative stroke (P = .002). Some 80.3% of these recipients were smaller female patients with male donors. Total ventricular mass mismatch from +30% to +50% was not associated with worse survival (P = .17). CONCLUSIONS: Total ventricular mass mismatch greater than +50% is associated with worse 1-year survival, although this group comprises a small portion of heart transplant. total ventricular mass mismatch from +30% to +50% is not associated with worse survival. These outcomes should be considered in selecting donors and in efforts to expand the potential donor pool.

Trends in Outcomes of Heart Transplants Using Extended Criteria Donors: A United Network for Organ Sharing Database Analysis.

BACKGROUND: Although the use of extended criteria donors (ECDs) is traditionally avoided because of poorer outcomes, management of heart transplant (HTx) recipients has evolved over the past decades. We sought to examine the temporal trends in outcomes of ECDs in HTx. METHODS: We queried the United Network for Organ Sharing database for adult HTx recipients who fit the EXPAND Trial criteria for ECDs: ischemic time ≥ 4 hours, ejection fraction < 50%, age > 55 years, and history of coronary artery disease. Transplant years were stratified into the following 4 periods: (1) 2000 to 2004, (2) 2005 to 2009, (3) 2010 to 2014, and (4) 2014 to 2018. The 2-sample t test, Kaplan-Meier survival analysis, log-rank test, analysis of variance, multivariable Cox proportional hazards, and multinomial logistic regression were used to compare data between periods. RESULTS: Through periods 1 to 4, 39,028 patients were stratified as follows: 9217 (2942 ECDs, 31.9%), 9224 (2730 ECDs, 29.6%), 10,309 (2762 ECDs, 26.8%), and 10,278 (2190 ECDs, 21.3%). Transplants using ECDs in periods 1 and 2 had increased 1-year mortality compared with periods 3 and 4 (16.9% and 15.6% vs 11.9% and 10.9% respectively, P < .001). Later periods also demonstrated improved Karnofsky scores (P < .001). CONCLUSIONS: Although use of ECDs decreased across the periods, we noted significant improvement in 1-year survival rates and postoperative functional status.

Geographic Variation in Heart Transplant Extended Criteria Donors in the United States.

BACKGROUND: Recent research has explored the use of higher risk extended criteria donors (ECDs) as a means of expanding the donor pool for heart transplantation. Here we sought to explore the current geographic distribution and survival outcomes of ECD utilization in various regions across the United States. METHODS: The United Network for Organ Sharing database was retrospectively queried for adult primary heart transplantation from 2000 to 2019. The EXPAND trial definition of ECD was used: ischemic time ≥ 4 hours, ejection fraction < 50%, age > 55 years, and history of coronary artery disease. Geographic data and 2019 population estimates were obtained from the US Census Bureau. RESULTS: Of the 42 642 transplants included in our analysis, 11 750 (27.6%) used ECDs. Region utilization of ECDs ranged from 18.4% to 46.5% of transplants. Region 6 had the highest utilization rate at 46.5%; this was primarily driven by the number of transplants with ischemic time ≥ 4 hours. Region 6 encompasses the largest total area (1.08 million square miles) and smallest population density (15.6 people per square mile). Region 8 had the lowest marginal donor utilization rate at 18.4%. Regions with high utilization of low ejection fractions, older donors, and donors with coronary artery disease (ie, regions 1 and 2) were able to maintain an average utilization rate of ECDs by maintaining short ischemic times. CONCLUSIONS: Large discrepancies in the use of ECDs exist across the different United Network for Organ Sharing regions. This is primarily driven by longer ischemic times, likely guided by variance in population densities between different regions.

Interaction between ischemic time and donor age under the new donor heart allocation system: Effect on post-transplant survival.

BACKGROUND: Ischemic time (IT) under the new heart transplant (HTx) allocation system has increased compared to the old system. We investigated the effect of IT and donor age on post-HTx survival. METHODS: The United Network for Organ Sharing (UNOS) database was analyzed to identify adult HTx between October 2015 and August 2020. Recipients were stratified by donor age, transplantation era, and IT. Kaplan-Meier and log-rank tests were used to compare 180-day post-HTx mortality. Cox proportional hazards modeling and propensity score matching were performed to adjust for confounders. RESULTS: Under the new system (N = 3654), IT≥4 h led to decreased survival compared to IT < 4 h (91.4% vs. 93.7%; P = .02), although this decrease was undetectable among those with donors ≥39 years old (90.4% vs. 91.1%; P = .73). IT≥4 h led to decreased survival with donors < 39 years old (91.7% vs. 94.6%; P < .01). Under the old system (N = 5987), IT≥4 h resulted in decreased survival (89.8% vs. 93.9%; P < .01), including with donors ≥39 years old (86.9% vs. 92.4%; P < .01). CONCLUSIONS: IT≥4 h remains a risk for post-HTx mortality under the new system. However, the magnitude of this effect is blunted when donor age is ≥39 years, likely secondary to increased allocation of these organs to lower status, more stable recipients.

Prolonged waitlisting is associated with mortality in extracorporeal membrane oxygenation-supported heart transplantation candidates.

Objective: Heart transplantation (HTx) candidates supported with venoarterial extracorporeal membrane oxygenation (ECMO) may be listed at highest status 1 but are at inherent risk for ECMO-related complications. The effect of waitlist time on postlisting survival remains unclear in candidates with ECMO support who are listed using the new allocation system. Methods: Adult candidates listed with ECMO for a first-time, single-organ HTx from October 18, 2018, to March 21, 2021, in the Scientific Registry of Transplant Recipients database were included and stratified according to waitlist time (≤7 vs ≥8 days). Postlisting outcomes were compared between cohorts. Results: Among 175 candidates waitlisted for ≤7 days, 162 (92.6%) underwent HTx whereas 13 (7.4%) died/deteriorated compared with 41 (57.8%) and 21 (29.6%) of the 71 candidates waitlisted for ≥8 days, respectively (P < .01). Blood type O candidates (odds ratio [OR], 2.94; 95% CI, 1.54-5.61) were more likely to wait ≥8 days whereas candidates with concurrent intra-aortic balloon pump were less likely (OR, 0.30; 95% CI, 0.10-0.89). Obesity was additionally associated among those listed at status 1 (OR, 2.04; 95% CI, 1.00-4.17). Waitlisting for ≥8 days was independently associated with 90-day postlisting mortality conditional on survival to day 8 postlisting (hazard ratio, 5.59; 95% CI, 2.59-12.1). Candidates listed at status 1 showed similar trends (hazard ratio, 5.49; 95% CI, 2.39-12.6). There was no significant difference in 90-day post-HTx survival depending on whether a candidate waited for ≥8 days versus ≤7 days (92.7 vs 92.0%; log rank P = .87). Conclusions: Among ECMO-supported candidates, obtaining HTx within 1 week of listing might improve overall survival.

Durable Left Ventricular Assist Device as a Bridge to Heart Transplantation Under the New Donor Heart Allocation System.

The new donor heart allocation system prioritizes candidates supported by temporary devices. However, waitlist and posttransplant outcomes in candidates with durable left ventricular assist device (LVAD) remain to be elucidated. The United Network for Organ Sharing database was queried for adults listed from October 2015 to March 2020 for a single-organ, first-time heart transplant (HTx) with a durable LVAD. Waitlist removal within 1 year because of death or clinical deterioration and HTx was analyzed using competing risks regression. Candidates who underwent HTx within 1 year of listing were identified for examination of post-HTx survival using the Kaplan-Meier method and Cox proportional hazards models. Compared with candidates listed under the old system (n = 2,122), candidates listed under the new system (n = 1,562) were slightly younger ( p = 0.04) but had higher body mass index ( p < 0.01). Those listed under the new system were significantly less likely to experience waitlist removal because of death or clinical deterioration (subhazard ratio [HR] 0.68, 95% CI 0.52-0.90) but were also less likely to undergo HTx (sub-HR 0.91, 95% CI 0.83-0.998). Those who survived to HTx were more likely to experience death or need for re-HTx within 1 year of HTx under the new system (adjusted HR 1.50, 95% CI 1.11-2.03). Candidates with durable LVAD experience favorable waitlist outcomes under the new allocation system, although those who undergo HTx may be at increased mortality risk. Thus, candidates with a durable LVAD should be carefully selected for HTx listing under the new allocation system.

Microaxial Left Ventricular Assist Device Versus Intraaortic Balloon Pump as a Bridge to Transplant.

BACKGROUND: Heart transplantation (HTx) candidates supported by Impella (Abiomed, Danvers, MA) or intraaortic balloon pump (IABP), who demonstrate evidence of cardiogenic shock, may qualify for waitlist status 2 without exception under the new donor heart allocation system. However limited data comparing Impella versus IABP as a bridge to HTx exist. METHODS: The United Network for Organ Sharing database was queried for adults listed and/or transplanted between January 2014 and February 2020. Temporal trends regarding Impella and IABP use were analyzed using the Royston trend test and χ2 test. Waitlist mortality was examined using Fine-Gray competing risks analysis. Post-HTx 180-day survival was analyzed using the Kaplan-Meier method and Cox proportional hazards models. RESULTS: Impella use increased from 0.2% in 2014 to 2.6% in 2020 (P < .01) and from 0.4% to 2.2% (P < .01) under the new allocation system. IABP use increased from 4.9% in 2014 to 27.6% in 2020 (P < .01) and from 6.7% to 26.6% (P < .01) under the new allocation system. Post-HTx survival was similar between groups (adjusted hazard ratio, 0.82; 95% CI, 0.38-1.78) despite more preoperative ventilation (3.6% vs 1.1%, P = .01) and higher model for end-stage liver disease excluding international normalized ratio scores (12.4 vs 9.5, P < .01) among Impella-supported recipients. Under the new system Impella-supported candidates were at higher risk of waitlist delisting compared with IABP-supported candidates (subhazard ratio, 2.42; 95% CI, 1.19-4.92). CONCLUSIONS: Post-HTx survival is comparable between Impella-supported and IABP-supported recipients despite worse preoperative profiles among Impella-supported recipients. Higher risk of waitlist delisting among Impella-supported candidates under the new allocation system requires close attention.

Successful use of Impella 5.5 to manage cardiogenic shock complicated by COVID-19.

BACKGROUND: Acute decompensated heart failure in patients with coronavirus disease 2019 (COVID-19) is becoming increasingly common. AIMS: In this case report, we describe the successful use of an Impella 5.5 (Abiomed) to treat cardiogenic shock refractory to inotropic therapy. MATERIALS & METHODS: Transthoracic and transesophageal echocardiography confirmed severely diminished left ventricular ejection fraction and a reverse-transcription polymerase chain reaction test revealed that the patient was COVID-19 positive during his hospital admission. RESULTS: Following initiation of inotropic therapy, we placed an Impella 5.5 for further cardiac support. The patient's LVEF and cardiac index improved after 21 days on the Impella 5.5 and was maintained following explant. DISCUSSION & CONCLUSION: The findings reported here demonstrate successful use of an Impella 5.5 to improve native heart function in refractory cardiogenic shock and further indicate its use as an option for those in acute decompensated heart failure who have tested positive for COVID-19 infection.

Bridging With Extracorporeal Membrane Oxygenation Under the New Heart Allocation System: A United Network for Organ Sharing Database Analysis.

BACKGROUND: The effect of the new donor heart allocation system on survival following bridging to transplantation with venous-arterial extracorporeal membrane oxygenation remains unknown. The new allocation system places extracorporeal membrane oxygenation-supported candidates at the highest status. METHODS: The United Network for Organ Sharing database was queried for adults bridged to single-organ heart transplantation with extracorporeal membrane oxygenation from October 2006 to February 2020. Association between implementation of the new system and recipient survival was analyzed using Kaplan-Meier estimates, Cox proportional hazards models, and propensity score matching. RESULTS: Of 364 recipients included, 173 and 191 were transplanted under new and old systems, respectively. Compared with the old system, waitlist time was halved under the new system (5 versus 10 days, P<0.01); recipients also demonstrated lower rates of prior cardiac surgery (32.9% versus 44.5%, P=0.03) and preoperative ventilation (30.6% versus 42.4%, P=0.02). Unadjusted 180-day survival was 90.2% (95% CI, 84.7%-94.2%) and 69.6% (95% CI, 62.6%-76.1%) under the new and old systems, respectively. Cox proportional hazards analysis demonstrated listing and transplantation under the new system to be an independent predictor of post-transplant survival (adjusted hazard ratio, 0.34 [95% CI 0.20-0.59]). Propensity score matching demonstrated a similar trend (hazard ratio, 0.36 [95% CI, 0.19-0.66]). Candidates listed under the new system were significantly less likely to experience waitlist mortality or deterioration (subhazard ratio, 0.38 [95% CI, 0.25-0.58]) and more likely to survive to transplant (subhazard ratio, 4.29 [95% CI, 3.32-5.54]). CONCLUSIONS: Recipients transplanted following extracorporeal membrane oxygenation bridging to transplantation under the new system achieve greater 180-day survival compared with the old and demonstrate less preoperative comorbidity. Waitlist outcomes have also improved significantly under the new allocation system.