Impact of the new heart allocation policy on patients with restrictive, hypertrophic, or congenital cardiomyopathies

Comparable Short-Term Survival in HIV-Positive and HIV-Negative Dual Organ Heart Transplant Recipients: A Call for Increased Access to Organ Donation for People Living with HIV

Access to organ transplantation for HIV-positive individuals is expanding, yet the outcomes of HIV-positive patients requiring multiorgan transplant are not well-defined. Adult individuals in the United Network for Organ Sharing (UNOS) registry who were HIV-positive and received HT between 2010 and 2023 were included. The primary outcome was patient survival. During the study period, 175 HIV-positive patients were transplanted. Twenty-six (14.8%) underwent dual organ transplantation (20 heart/kidney, 4 heart/lung, and 2 heart/liver) at 23 centers. Median age at the time of HT was 56 years (IQR 47-60), majority were male (n=18, 69%), and 46% identified as Black (n= 12). Dilated cardiomyopathy was the most common etiology of heart failure (n=13, 50%). All patients received organs from HIV-negative donors. The probability of surviving at least one year was 87.6% (95% CI 81.0- 92.0) for single-organ recipients and 82.9% for dual organ recipients (95% CI 60.0-93.4). There was no difference in overall survival between HIV-positive and HIV-negative matched controls among dual organ recipients (log-rank p-value = 0.8). Over the last decade, only a small number of HIV-positive individuals with end-stage heart failure have undergone dual organ transplantation with encouraging short-term outcomes.

Nonlinear effect of body mass index on postoperative survival following isolated heart transplantation

Background

Guidelines regarding recipient's body mass index (BMI) for heart transplant are evolving with variable cutoffs depending on the country and institution. It is imperative to provide updated nonlinear estimates of postoperative risk attributable to a recipient's BMI to evaluate the relevance of existing cutoffs.

Methods

A total of 30,787 patients were analyzed from the United Network for Organ Sharing (UNOS) database. Patients receiving an isolated heart transplant ages 18 and older since 2010 were included. Overall survival was the primary outcome. A multivariate Cox proportional hazards model was applied and included a penalized smoothing spline term for recipient BMI and risk factors such as diabetes. We assessed the overall significance of the nonlinear penalized spline terms using an asymptotic Wald test.

Results

The cohort consisted of 662 (2.2%) BMI <18.5, 9,359 (30%) BMI 18.5 to 24.9, 10,997 (36%) BMI 25 to 29.9, 9,550 (31%) BMI 30 to 39.9, and 206 (0.7%) BMI ≥40 patients. The nonlinear spline terms for recipient BMI were statistically significant (p < 0.01). The hazard ratio (HR) appeared to grow linearly in BMI at an inflection point of BMI = 26. No inflection point was observed at either of the International Society for Heart and Lung Transplantation recommended cutoffs of BMI = 30 (HR 1.11, confidence interval [CI] 1.07-1.15) or BMI = 35 (HR 1.29, CI 1.24-1.37).

Conclusions

After multivariable adjustment, there is no sharp cutoff in survival risk at either BMI = 30 or BMI = 35. Unlike previously reported, postoperative survival risk grows approximately linearly in the BMI range from 26 to 40.

Impact of the New Heart Allocation System on the Medium-Term Outcomes in Patients With Hypertrophic Cardiomyopathy

The introduction of the new heart allocation system in the United States in 2018 resulted in an increase in the number of heart transplants (HT) performed among patients with hypertrophic cardiomyopathy (HCM). However, whether that affected medium-term post-HT outcomes in this group of patients remains unknown. We conducted an analysis of the United Network for Organ Sharing Transplant Database, including adults with HCM who underwent heart transplantation between 2015 and 2021. Patients were divided into two equal-duration eras: Era 1 (October 17, 2015, to October 17, 2018) and Era 2 (October 18, 2018, to October 18, 2021). In the studied period, 444 patients with HCM underwent HT: 204 in Era 1 and 240 in Era 2. In Era 2, the waitlist time was shorter, transplant rates were higher, patients were less frequently supported with inotropes but more often with an IABP, ischemic time was longer, and donor-to-recipient distance larger. Pre- and post-transplant functional status was comparable across the two eras, while the pre-HT employment rate was higher in the new system. The 3 year survival was unchanged across eras. In the new allocation system, despite more frequent mechanical circulatory support (MCS) use and increased ischemic time, the medium-term outcomes of patients with HCM remained favorable.

Assessing the Role of Primary Heart Failure Etiology on Cardiac Transplant Outcomes

BACKGROUND

There are diverse indications for heart transplantation (HTx), often categorized into ischemic (ICM) and nonischemic (NICM) cardiomyopathy. Although there is extensive research comparing the outcomes for these disease processes following certain therapeutic interventions, there are limited data on how recipient etiology impacts post-HTx survival. Our investigation seeks to identify this relationship.

METHODS

We conducted a retrospective analysis using adult HTx patients from the United Network for Organ Sharing database between 2000 and 2021. Patients with a combined heart-lung transplant or previous HTx were excluded. ICM included coronary artery disease (CAD) and ischemic dilated cardiomyopathy. NICM included nonischemic dilated (NIDCM), hypertrophic (HCM), and restrictive (RCM) cardiomyopathy. Overall survival was analyzed using Kaplan-Meier curves, log-rank tests, and multivariable Cox regression models.

RESULTS

A total of 42 268 patients were included in our study. Recipients with ICM were older and more likely to be males, obese, diabetics, and smokers. We found that patients with ICM had an increased incidence of transplant CAD (OR = 1.23, p < 0.001) and risk of mortality (hazard ratio [HR] = 1.22, p < 0.001) compared to NICM. When NICM was expanded, RCM had a similar hazard risk compared to ICM (HR = 1.03, p = 0.650), whereas both NIDCM (HR = 0.81, p < 0.001) and HCM (HR = 0.70, p < 0.001) had improved survival.

CONCLUSION

Our study provides evidence to suggest that ICM has decreased survival when compared to NICM. When NICM was expanded, RCM was found to have an increased mortality risk similar to ICM, whereas NIDCM and HCM both had superior outcomes. The clinical implication of this investigation will allow clinicians to better understand the prognosis of certain patient groups.

Prognosis after heart transplant in patients with hypertrophic and restrictive cardiomyopathy. A nationwide registry analysis

INTRODUCTION AND OBJECTIVES

Posttransplant outcomes among recipients with a diagnosis of hypertrophic cardiomyopathy (HCM) or restrictive cardiomyopathy (RCM) remain controversial.

METHODS

Retrospective analysis of a nationwide registry of first-time recipients undergoing isolated heart transplant between 1984 and 2021. One-year and 5-year mortality in recipients with HCM and RCM were compared with those with dilated cardiomyopathy (DCM).

RESULTS

We included 3703 patients (3112 DCM; 331 HCM; 260 RCM) with a median follow-up of 5.0 [3.1-5.0] years. Compared with DCM, the adjusted 1-year mortality risk was: HCM: HR, 1.38; 95%CI, 1.07-1.78; P=.01, RCM: HR, 1.48; 95%CI, 1.14-1.93; P=.003. The adjusted 5-year mortality risk was: HCM: HR, 1.17; 95%CI, 0.93-1.47; P=.18; RCM: HR, 1.52; 95%CI, 1.22-1.89; P<.001. Over the last 20 years, the RCM group showed significant improvement in 1-year survival (adjusted R2=0.95) and 5-year survival (R2=0.88); the HCM group showed enhanced the 5-year survival (R2=0.59), but the 1-year survival remained stable (R2=0.16).

CONCLUSIONS

Both RCM and HCM were linked to a less favorable early posttransplant prognosis compared with DCM. However, at the 5-year mark, this unfavorable difference was evident only for RCM. Notably, a substantial temporal enhancement in both early and late mortality was observed for RCM, while for HCM, this improvement was mainly evident in late mortality.

Challenges with the current United Network for Organ Sharing heart allocation system

PURPOSE OF REVIEW

The revised United States heart organ allocation system was launched in October 2018. In this review, we summarize this United Network for Organ Sharing (UNOS) policy and describe intended and unintended consequences.

RECENT FINDINGS

Although early studies published after the change suggested postheart transplant survival declined at 6 months and 1 year, recent publications with longer follow-up time have confirmed comparable posttransplant survival in adjusted models and several patient cohorts. Moreover, the new allocation decreased overall waitlist time from 112 to 39 days ( P  < 0.001). Mean ischemic time increased because of greater distances traveled to acquire donor hearts under broader sharing. Despite the intention to decrease exception requests by expanding the number of priority tiers to provide more granular risk stratification, ∼30% of patients remain waitlisted under exception status. Left-ventricular assist device (LVAD) implants are declining and the number of LVAD patients on the transplant list has decreased dramatically after the allocation system change.

SUMMARY

As the next allocation system is developed, it is imperative to curtail the use of temporary mechanical support as a strategy solely for listing purposes, identify attributes that more clearly stratify the severity of illness, provide greater oversight of exception requests, and address concerns regarding patients with durable LVADs.

Impact of the 2018 UNOS Heart Transplant Policy Changes on Patient Outcomes

In 2018, the United Network for Organ Sharing implemented a 6-tier allocation policy to replace the prior 3-tier system. Given increasing listings of critically ill candidates for heart transplantation and lengthening waitlist times, the new policy aimed to better stratify candidates by waitlist mortality, shorten waiting times for high priority candidates, add objective criteria for common cardiac conditions, and further broaden sharing of donor hearts. There have been significant shifts in cardiac transplantation practices and patient outcomes following the implementation of the new policy, including changes in listing practices, waitlist time and mortality, transplant donor characteristics, post-transplantation outcomes, and mechanical circulatory support use. This review aims to highlight emerging trends in United States heart transplantation practice and outcomes following the implementation of the 2018 United Network for Organ Sharing heart allocation policy and to address areas for future modification.

Impact of the new UNOS donor heart allocation system on waitlist outcomes and early posttransplant mortality among adults with congenital heart disease

Adults with congenital heart disease (ACHD) experience worse waitlist outcomes and higher early posttransplant mortality compared to non-ACHD patients. On October 18, 2018; the UNOS donor heart allocation system was redesigned giving unique listing status to ACHD patients. The impact of this change on outcomes in transplant-listed patients is unstudied. Using the Scientific Registry of Transplant Recipients (SRTR) we compared ACHD patients listed for the first-time for heart transplantation from two eras of equal duration. We analyzed waitlist outcomes, posttransplant mortality and length of stay among ACHD patients in both eras and between ACHD and non-ACHD patients in the new era. Of 12 723 listed patients, 535 had ACHD (293 in the new era) and 12 188 did not (6258 in the new era). A total of 163 (56%) ACHD patients in the new era versus 150 (62%) in the prior era were transplanted; 11 (3.8%) versus 15 (6.2%) died on the waitlist; 32 (11%) versus 35 (14%) were delisted and 15 (9.2%) versus 19 (12.7%) died within 30 days of transplant, respectively. The new UNOS donor heart allocation system improved waitlist time and decreased the proportion not transplanted during the first 300 days after listing among ACHD patients without altering early posttransplant outcomes or significantly changing the gap in outcomes compared to non-ACHD patients.

Evolving Characteristics of Heart Transplantation Donors and Recipients: JACC Focus Seminar

Although the burden of end-stage heart failure continues to increase, the number of available organs for heart transplantation (HT) remains inadequate. The HT community has been challenged to find ways to expand the number of donor hearts available. Recent advances include use of hearts from donors infected with hepatitis C virus as well as other previously underutilized donors, including those with left ventricular dysfunction, of older age, and with a history of cocaine use. Concurrently, emerging trends in HT surgery include donation after circulatory death, ex vivo normothermic heart perfusion, and controlled hypothermic preservation, which may enable procurement of organs from farther distances and prevent early allograft dysfunction. Contemporary HT recipients have also evolved in light of the 2018 revision to the U.S. heart allocation policy. This focus seminar discusses recent trends in donor and recipient phenotypes and management strategies for successful HT, as well as evolving areas and future directions.

Restrictive cardiomyopathy: from genetics and clinical overview to animal modeling

Restrictive cardiomyopathy (RCM), a potentially devastating heart muscle disorder, is characterized by diastolic dysfunction due to abnormal muscle relaxation and myocardial stiffness resulting in restrictive filling of the ventricles. Diastolic dysfunction is often accompanied by left atrial or bi-atrial enlargement and normal ventricular size and systolic function. RCM is the rarest form of cardiomyopathy, accounting for 2-5% of pediatric cardiomyopathy cases, however, survival rates have been reported to be 82%, 80%, and 68% at 1-, 2-, and 5-years after diagnosis, respectively. RCM can be idiopathic, familial, or secondary to a systemic disorder, such as amyloidosis, sarcoidosis, and hereditary hemochromatosis. Approximately 30% of cases are familial RCM, and the genes that have been linked to RCM are cTnT, cTnI, MyBP-C, MYH7, MYL2, MYL3, DES, MYPN, TTN, BAG3, DCBLD2, LNMA, and FLNC. Increased Ca2+ sensitivity, sarcomere disruption, and protein aggregates are some of the few mechanisms of pathogenesis that have been revealed by studies utilizing cell lines and animal models. Additional exploration into the pathogenesis of RCM is necessary to create novel therapeutic strategies to reverse restrictive cardiomyopathic phenotypes.

Critically appraising the 2018 United Network for Organ Sharing donor allocation policy: adding life boats or rearranging the deck chairs?

PURPOSE OF REVIEW

Due to the growing mismatch between donor supply and demand as well as unacceptably high transplant waitlist mortality, the heart organ allocation system was revised in October 2018. This review gives an overview of the changes in the new heart organ allocation system and its impact on heart transplant practice and outcomes in the United States.

RECENT FINDINGS

The 2018 heart allocation system offers a 6-tiered policy and therefore prioritizes the sickest patients on the transplant waitlist. Patients supported with temporary mechanical circulatory support devices are prioritized as Status 1 or Status 2, resulting in increased utilization of this strategy. Patients supported with durable left ventricular assist devices have been prioritized as Status 3 or 4, which has resulted in decreased utilization of this strategy. Broader geographic sharing in the new heart allocation system has resulted in prolonged donor ischemic times. Overall, the new heart allocation system has resulted in significantly lower candidate waitlist mortality, shorter waitlist times, and higher incidence of transplantation.

SUMMARY

The new United Network for Organ Sharing allocation policy confers significant advantages over the prior algorithm, allowing for decreased waitlist times and improved waitlist mortality without major impact on posttransplant survival.

Outcomes after heart transplantation in patients with cardiac sarcoidosis

Background

The number of patients with sarcoidosis requiring heart transplantation (HT) is increasing. The aim of this study was to evaluate outcomes of isolated HT in patients with sarcoid cardiomyopathy and compare them to recipients with non‐ischaemic restrictive or dilated cardiomyopathy.

Methods and results

Adult HT recipients were identified in the UNOS Registry between 1990 and 2020. Patients were grouped according to diagnosis. The cumulative incidences for the all‐cause mortality and rejection were compared using Fine and Gray model analysis, accounting for re‐transplantation as a competing risk. Rejection was evaluated using logistic regression analysis. We also reviewed characteristics and outcomes of all HT recipients with previous diagnosis of sarcoid cardiomyopathy from a single centre. A total of 30 160 HT recipients were included in the present study (n = 239 sarcoidosis, n = 1411 non‐ischaemic restrictive cardiomyopathy, and n = 28 510 non‐ischaemic dilated cardiomyopathy). During a total of 194 733 patient‐years, all‐cause mortality at the latest follow‐up was not significantly different when comparing sarcoidosis to non‐ischaemic dilated cardiomyopathy [adjusted subhazard ratio (aSHR) 1.46, 95% confidence intervals (CIs): 0.9–2.4, P = 0.12] or restrictive cardiomyopathy (aSHR 1.12, 95% CI: 0.65–1.95, P = 0.67). Accordingly, multivariable analysis suggested that 1 year mortality was not significantly different between sarcoidosis and non‐ischaemic dilated cardiomyopathy (aSHR 1.56, 95% CI: 0.9–2.7, P = 0.12) or restrictive cardiomyopathy (aSHR 1.15, 95% CI: 0.61–2.18, P = 0.66). No differences were observed regarding 30 day mortality, treated and hospitalized acute rejection, and 30 day death from graft failure after HT. Thirty‐day mortality did not improve significantly in more recent HT eras whereas there was a trend towards improved 1 year mortality in the latest HT era (P = 0.06). Data from the single‐centre case review showed excellent long‐term outcomes with sirolimus‐based immunosuppression.

Conclusions

Short‐term and long‐term post HT outcomes among patients with sarcoid cardiomyopathy are similar to those with common types of non‐ischaemic cardiomyopathy.

Exception-Status Listing: A Critical Pathway to Heart Transplantation for Adults With Congenital Heart Diseases

Adults with congenital heart diseases may not be candidates for conventional therapies to control ventricular systolic dysfunction, including mechanical circulatory support, which moves potential heart-transplantation recipients to a listing status of higher priority. This results in longer waitlist times and greater mortality rates. Exception-status listing allows a pathway for this complex and anatomically heterogenous group of patients to be listed for heart transplantation at appropriately high listing status. Our study queried the United Network for Organ Sharing registry to evaluate trends in the use of exception-status listing among adults with congenital heart diseases awaiting heart transplantation. Uptrend in the use of exception-status listing precedes the new allocation system, but it has been greatest since changes were made in the allocation system. It continues to remain a vital pathway for adults with congenital heart disease (whose waitlist mortality rates are often not characterized adequately by using the waitlist-status criteria) timely access to heart transplantation.

Changes in waitlist and posttransplant outcomes in patients with adult congenital heart disease after the new heart transplant allocation system

OBJECTIVE

In 2018, the United Network for Organ Sharing (UNOS) introduced new criteria for heart allocation. This study sought to assess the impact of this change on waitlist and posttransplant outcomes in adult congenital heart disease (ACHD) recipients.

METHODS

Between January 2010 and March 2020, we extracted first heart transplant ACHD patients listed from the UNOS database. We compared waitlist and post-transplant outcomes before and after the policy change.

RESULTS

A total of 1206 patients were listed, 951 under the old policy and 255 under the new policy. Prior to transplant, recipients under the new policy era were more likely to be treated with extracorporeal membrane oxygenation (P = .018), and have intra-aortic balloon pumps (P < .001), and less likely to have left ventricular assist devices (P = .027).Compared to patients waitlisted in the pre-policy change era, those waitlisted in the post policy change era were more likely to receive transplants (P = .001) with no significant difference in waiting list mortality (P = .267) or delisting (P = .915). There was no difference in 1-year survival post-transplant between the groups (P = .791).

CONCLUSION

The new policy altered the heart transplant cohort in the ACHD group, allowing them to receive transplants earlier with no changes in early outcomes after heart transplantation.