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Continuous Distribution of Hearts

eye iconAt a glance


The concept paper is intended to inform the heart transplantation community about a continuous distribution allocation framework, as well as describe the Heart Transplantation Committee’s initial efforts in transitioning from a classification-based allocation system to a continuous distribution allocation system. The paper provides a general overview of the components of continuous distribution. It also identifies the attributes chosen by the Committee for inclusion in the initial version of heart continuous distribution, and their initial efforts to develop rating scales for prioritizing candidates. The paper requests community feedback that will assist the Heart Transplantation Committee’s work.

Supporting media

General proposal information

Proposal information for patients


View presentation PDF link

Proposed concept

  • Continuous distribution will replace the current classification-based allocation system with a points-based allocation system. A points-based framework assigns a composite allocation score to each candidate.
  • A candidate’s composite allocation score will determine the order that organs are offered to candidates. 
  • A candidate’s composite allocation score will consider a combination of donor and candidate characteristics, which can include candidate medical urgency, post-transplant survival, candidate biology, patient access, and placement efficiency.

Anticipated impact

  • What it's expected to do
    • Provide a more equitable approach to matching candidates and donors
    • Remove hard boundaries between classifications that prevent candidates from being prioritized higher on the match run
    • Establish a system that is flexible enough to work for each organ type
  • What it won't do
    • This paper is not a proposed policy change, but the feedback gathered will help the Heart Transplantation Committee develop a future policy proposal

Terms to know

  • Attribute: Attributes are criteria used to classify,  sort, and prioritize candidates. For example, in heart allocation attributes can include blood type compatibility, mechanical support, heart failure therapies, and distance between candidate and donor hospitals.
  • Composite Allocation Score: A composite allocation score combines points from multiple attributes together. This concept paper proposes the use of composite allocation scores in a points-based framework.
  • Rating Scale: A rating scale describes how much preference is given to candidates within each attribute.
  • Weights: Weights reflect the relative importance or priority of each attribute in the overall composite allocation score. Combined with the ratings scale and each candidate’s information, this results in an overall composite score for prioritizing candidates.

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Read the full proposal (PDF)

eye iconComments

Region 8 | 09/19/2023

A member commented that surgeon and staff safety is paramount – and explained that if distance is added then there is an increased risk of transplant professionals safety issues due to more flights. Several members pointed out that there has been an increase in traveling since 2018 and suggested to look at the availability of local organs. Some attendees suggested the committee consider a focus on efficiency in allocation. They explained that transplant hospitals are facing increased demand on surgical teams and increased expenses related to changes in allocation across all organs, and that this is not a sustainable effort over time. In addition, patients are asking for increased transparency related to their position on the wait list. Another commented that continuous distribution makes it extremely challenging to provide this important information to patients and that the committee should keep in mind, and examine, the balance between equity and utility. The costs in terms of reduced efficiency, non-use, monetary cost, etc., need to be considered.

Association of Organ Procurements Organizations | 09/19/2023

Consistent with other previous public comments submitted on CD, AOPO views the continuous distribution framework as an effective way to balance multiple medical and placement efficiency factors that could positively impact heart utilization.

 AOPO supports balancing medical urgency with the post-transplant survival attributes to optimize organ utilization and increase the odds of long-term survival. With post-transplant survival not a factor in the current allocation system for heart, extensive modeling would be important to assess if there is risk for unintended impact to candidate accessibility. We rely on the expert transplant professionals to determine the most appropriate post-survival data points. AOPO appreciates the flexibility that continuous framework offers to ensure the most appropriate attributes while building rating scales.

AOPO supports reducing the biological disadvantages and patient access attributes to support equity in access to transplant and decrease the risk of mortality in the identified groups. Both components align with the requirements from NOTA and OPTN final rule on patient access.

Placement efficiency is critically important to AOPO. To ensure we are good stewards of the gift; it is important to appropriately balance proximity of the recipient transplant center to the donor hospital to minimize the heart’s ischemic time and with decreasing geographic access disparities, while considering transportation challenges. AOPO recommends the Committee consider the impact of heart preservation devices, increasingly utilized by transplant centers, on the ability to travel longer distances. Consistent with previous feedback on lung CD, AOPO encourages the Committee to consider donor factors that could impact the efficiency calculation. A more complex donor in combination with extended transportation time could impact acceptance rates, outcomes and utilization.

OPTN Transplant Administrators Committee | 09/19/2023

The OPTN Transplant Administrators Committee thanks the OPTN Heart Transplantation Committee for their dedication and work on this project. The initial concerns of the Committee lie in how proximity will be adjudicated. There is more to proximity than mileage, such as access to transportation, access to airports, time, and resources, and the Committee encourages the Heart Committee to reflect also on the accessibility of driving over flying in continuing this conversation of proximity. Another factor requiring consideration is where the transplant list is generated, as this can sometimes differ geographically from where the donor is located, due to organ procurement organizations moving donors to recovery centers. Lastly the Committee counsels that when evaluating post-transplant survival as a potential attribute; that the Heart Committee take the heart utilization numbers into consideration.

Region 9 | 09/19/2023

This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. A member expressed support for this concept.

OPTN Histocompatibility Committee | 09/19/2023

The OPTN Histocompatibility Committee strongly supports the concept paper on the Continuous Distribution of Hearts, and is especially supportive of including sensitization as an attribute in heart allocation. Sensitized heart candidates have historically had lower rates of transplantation and higher rates of waiting list mortality than unsensitized candidates, and including sensitization as a factor in allocation will help to increase equity for these candidates. The Committee recommends that the Heart Committee utilize unacceptable antigens, like in kidney, pancreas, and lung allocation, and allow for program-specific medical judgment on which antigens would be considered unacceptable rather than setting arbitrary MFI thresholds. MFI varies between sample preparation methods, instruments, and institutions, and allowing for clinical judgment and clinical practice-based decisions would better serve sensitized patients. The Committee also recommends a steep, non-linear curve for the rating scale for CPRA, similar to what was implemented for lung allocation.

Region 3 | 09/19/2023

One attendee recommended moving forward while also exploring the post-transplant survival attributes. Two attendees commented that the committee really needs to maximize efficiency as they move forward in this model. 

Abbott Laboratories | 09/19/2023

Thank you very much for the opportunity to publicly comment on the concept paper, “Continuous Distribution of Hearts”. Abbott commends the UNOS Heart Transplantation Committee (the Committee) for its thoughtful approach to heart distribution policy changes. Furthermore, we support the concept as it is a positive step towards more equitable distribution of hearts based upon creating a risk adjusted methodology for predicting the long-term transplant benefit of a specific heart donor-recipient match.

The 2018 changes in the heart recipient prioritization policy resulted in a hesitancy for clinical teams to use LVAD therapy as a bridge to cardiac transplantation (BTT) because waiting time for LVAD patients as a Status 4 has increased significantly. As a result, LVAD patients have a reduced rate for transplantation. Publications have shown that patients with LVADs will have longer wait times, as many centers moved to the use of temporary mechanical support to bridge patients who were otherwise transplant candidates. Consequently, LVAD recipients can wait years for a heart transplant. We agree with the Committee that the continuous distribution model for hearts should incorporate a risk adjustment factor for time on LVAD. Adjusting for this will result in better decision making regarding the most beneficial mode of bridging therapy by removing the negative bias that results from the use of a durable LVAD in the current system.

The Committee asked for public input on whether they should create a post-transplant survival attribute for inclusion in the first version of the framework. Abbott believes that the model should include a survival benefit measure. Since the cumulative risk that accounts for complications such as chronic allograft vasculopathy, increased risk of malignancies, opportunistic infections, and renal insufficiency may not be appreciated in short-term follow-up.

The Committee also asked the public for input on any specific information they should use to evaluate the success of a specific measure. Abbott recommends adjusting the way in which it proposes to evaluate the time on LVAD attribute. Currently, the Committee proposes to give points towards higher status when a patient experiences a complication. Instead, Abbott recommends risk adjusting for a patient’s likelihood of getting a complication rather than having to experience a complication to gain points.

Thank you again for the opportunity to comment on the Continuous Distribution of Hearts concept paper. Ultimately, with the inclusion of time on LVAD, the continuous heart distribution model will improve the allocation of hearts to those who need them the most urgently.

Region 10 | 09/19/2023

It was noted that the move to Continuous Distribution (CD) will create a more equitable waitlist for heart transplant candidates. Another attendee suggested the right ventricular failure that precludes consideration of LVAD should be added as an attribute for CD. Someone else added that it is unclear how proximity should be weighted in CD for heart transplantation, especially in the era of DCD utilization, normothermic regional perfusion, and machine perfusion. Another attendee noted that the OPTN needs to develop a plan on how to handle programs submitting exception requests in CD. There should be some level of holding programs accountable so that the system is not overrun with exceptions. Lastly, an attendee suggested that multi-organ candidates with congenital diagnoses or smaller candidates be considered as their own attribute. It is also an opportunity for the Heart Transplantation Committee to work with the Multi-Organ Transplantation Committee on the best path forward for multi-organ candidates in CD.

UC San Diego Health | 09/19/2023

The UCSD Health Center for Transplantation appreciates the update provided by the Heart Committee regarding their early progress on the development of a continuous allocation model and generally agrees that the attributes proposed for inclusion are appropriate.

• We would recommend that in addition to waiting time accrued with an implanted VAD or LVAD, the Committee consider include a pathway for candidates with demonstrated complications or intolerance to the implanted device.
• We appreciate that the Committee is recommending that the CHD and HCM/RCM recommendations in the current guidance document for exception requests be addressed in the initial version of continuous distribution and we urge the Committee to consider if there are other opportunities to move away from the current exception dependent practice.
• We acknowledge the community’s support for and generally agree with incorporating post-transplant survival as an attribute in any allocation system as a means to achieve the best use of donated organs. However, absent a reliable model for post-heart transplant survival, we support the Committee’s decision to exclude this attribute from the first iteration of continuous distribution
• With regards to placement efficiency, maintaining some semblance to the current system which considers distance between the donor and transplant hospital seems reasonable.
• We also recognize the challenge in fairly contributing points in a continuous distribution framework. We would urge the Committee to consider conducting a values prioritization exercise similar to that which the Liver and Intestinal Transplantation Committee recently circulated to the community to help inform the next steps.

Transplant Families | 09/18/2023

Transplant Families expresses its support for the OPTN Heart Transplantation Committee and their efforts to update continuous distribution. We also agree with the recommendations of the OPTN Pediatric Committee.

Firstly, the Committee proposes exploring the implementation of rating scales for the pediatric attribute. While all pediatric patients deserve prioritization in allocation, age, and weight should be weighed into the allocation criteria for pediatric candidates.

Secondly, we concur with the decision to grant priority to congenital heart conditions within the medical urgency attribute but suggest that the Committee carefully considers the distinctions between various congenital conditions in terms of urgency and mortality risk as spelled out in the document "Guidance for Pediatric Heart Exception Requests". In addition, we are thankful for the inclusion of specific types of cardiomyopathy that are ineligible for VAD to hold urgency.

We were very pleased to have the patient and parent voices included in these efforts and to see a well-rounded committee that sought out multiple data sources when making decisions. We are eager to help in ongoing discussions in a collaborative manner with the future Heart Committee Workgroup.

Region 7 | 09/18/2023

This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. An attendee suggested Continuous Distribution should include detailed analysis and consideration of the efficiency and logistics impacts. As has been seen with lungs, there is a need to look at this from a system standpoint, not just an individual committee standpoint. Another attendee noted concerns with various aspects like distance, size match, and ventricular assist devices. Continuous Distribution needs to be continuously monitored to see if it can be improved. Another attended suggested evaluating the weight given to proximity due to inconsistent use of machine perfusion. Lastly, an attendee noted that Continuous Distribution may add ongoing barriers to progress.

American Society of Transplant Surgeons | 09/18/2023

See attachment.

View attachment from American Society of Transplant Surgeons

OPTN Ad Hoc Disease Transmission Advisory Committee | 09/15/2023

The Ad Hoc Disease Transmission Advisory Committee (DTAC) appreciates the opportunity to provide feedback on this concept paper and supports the OPTN Heart Transplantation Committee’s efforts to move toward continuous distribution. DTAC members identified that continuous distribution changes could impact travel patterns for organ distribution and it is important to consider that transplant centers in certain parts of the country may be less familiar with diseases endemic to other parts of the country. DTAC has continued its work to mitigate endemic disease transmission through organ transplant through efforts such as DTAC’s proposal, Improve Deceased Donor Evaluation for Endemic Diseases. This proposal is pending policy implementation and requires targeted screening for Trypanosoma cruzi. The OPTN Heart Transplantation Committee should consider increased endemic disease transmission in developing its continuous distribution policy proposal, and also consider education or guidance on screening of donors to minimize communication issues about test results for areas with differences in endemic testing.

Gift of Life Michigan | 09/15/2023

We support the development of Continuous Distribution modeling for heart transplantation.

Kevin Daly | 09/15/2023

I applaud the UNOS Heart Committee for beginning the process of developing a continuous distribution system and heart allocation score. I will be watching this work closely and hope that many opportunities to engage in discussion are offered as the system is developed. I agree with giving priority to sensitized candidates adjusted for blood group. Some thought will have to go into how this will interact with pediatric candidates who are listed as eligible for ABOi transplant.

Several items deserve close attention: (1) Accurate risk assessment for congenital heart disease candidates (2) Size based priority in heart allocation (3) Waiting Time

1. Accurate risk assessment for congenital heart disease candidates

The current pediatric and adult allocation systems use congenital heart disease physiology to determine allocation priority to some extent. In fact the adult regional review board guidance is quite specific as to how single ventricle vs. two-ventricle congenital heart disease should be assessed when considering status exceptions. The OPTN/SRTR database currently does not capture any information about congenital heart disease physiology, even though it is a vital characteristic for any urgency and post-transplant survival modeling. I would recommend that the following physiologic categories are added to the OPTN/SRTR database:

a. Single ventricle congenital heart disease with pulmonary blood supply via shunt, restricted pulmonary artery, or ductus arteriosus
b. Single ventricle congenital heart disease with pulmonary blood supply via a superior cavopulmonary anastomosis
c. Single ventricle congenital heart disease with pulmonary blood supply via a total cavopulmonary anastomosis (Fontan)
d. Two ventricle congenital heart disease with systemic left ventricle
e. Two ventricle congenital heart disease with systemic right ventricle
f. Two ventricle congenital heart disease with unrestrictive VSD and pulmonary blood supply via a shunt, restricted pulmonary artery, or ductus arteriosus
g. Two ventricle congenital heart disease with unrestrictive VSD and pulmonary blood supply via a superior cavopulmonary anastomosis

Since the OPTN/SRTR database does not currently capture this information, and modeling of outcomes is key to developing the continuous distribution model, I would recommend that the OPTN/SRTR database is linked to another large database which does capture this information such as the Pediatric Heart Transplant Society Database and/or the Society for Thoracic Surgery Database. This would allow the rich data the currently exists to be used in modeling for the allocation system.

2. Size based priority in heart allocation

I agree with the comment of the UNOS Pediatric Transplant Committee that binary allocation of pediatric priority points may not be the best way to achieve some amount of pediatric preference. Different pediatric subpopulations are affected differently by the current allocation system. For example, fully grown teenagers have access to adult heart donors which allows transplantation rates to be relatively high in this group. Younger pediatric candidates, particularly those under 25 kg in size who are blood type O, face a much more restricted donor pool. Even at the highest priority status (1A), these candidates can experience median waiting times of 3-4 months with some non-sensitized patients waiting over 6 months in hospital at the highest allocation status. (Ref: Williams RJ, et. al. Pediatric heart transplant waiting times in the United States since the 2016 allocation policy change. Am J Transplant. 2022 Mar;22(3):833-842. doi: 10.1111/ajt.16921.) This is primarily driven by a limited donor pool for smaller pediatric candidates despite a compelling urgency and need. Even a continuous distribution system will not solve this problem because the primary issue is low donor availability. However, a system where 25-50 kg candidates are given additional priority for oversized (but surgically appropriate) donors would then allow 10-25 kg candidates to have more access to appropriately sized donors. This type of domino effect where each group is given some additional priority to take a slightly oversized donor may help alleviate some of the supply constraints. The committee may want to consider one set of points for donor-recipient size matching and another set of points for pediatric candidates writ large. I would also note that similar size issue likely exist for large adult transplant candidates where the donor pool may also be quite limited. These candidates may also deserve additional size based priority points.

3. Waiting Time

I support the concept of including total waiting time (active + inactive) in calculating this variable. Patients who do experience complications and need to be made temporarily inactive should not be punished for the complication. Such a patient remains at risk for waitlist mortality during the inactive period but they receive no benefit in terms of potential for a transplant offer. In addition the current system disincentivizes programs to actively manage their list and place candidates who are temporarily too sick for transplantation into inactive status because of the effect on accrued waiting time. As a result there are system efficiency concerns about organ offer acceptance that could be improved by removing this disincentive.

I would also implore the Heart committee to consider when waiting time should start. Does it have to be at the time of listing, or is there another proxy for onset of advanced heart failure that can be utilized? Our kidney transplant colleagues use the earlier of (1) initiation of dialysis or (2) transplant listing. For some cardiac patients we could use date of LVAD implant or initiation of MCS. This may also improve transplant equity as certain patient populations may have been offered destination LVAD because they were not felt to be transplant candidates. If our assessment changes such that transplant becomes an option, should they not receive credit for time since LVAD implant?

View attachment from Kevin Daly

OPTN Lung Transplantation Committee | 09/15/2023

The OPTN Lung Transplantation Committee thanks the OPTN Heart Transplantation Committee for this concept paper and their work towards continuous distribution. Members urge the Committee to consider access to transplant for congenital heart-lung candidates, specifically those with heart status three through five, as these patients are very ill and seem to wait a long time for transplant. It has been a challenge to transplant these candidates due to most of these heart offers being unsuitable for multi-organ candidates, and because the heart status generally drives allocation for these candidates (the heart pulls the lung). These candidates appear to be disadvantaged in the current system.

Region 6 | 09/15/2023

One attendee commented that the committee should consider geographic equity as an attribute. They added that region 6 borders the ocean so using nautical miles and circles is problematic. They suggested possibly using population density as a proxy. Another attendee commented that the lung community has experienced logistical inefficiencies in lung continuous distribution given the volume of offers and recommended the committee consider that while developing their policy. One attendee added that logistical challenges, resource utilization and cost need to be considered to avoid late turndowns and non-utilization of organs. Another attendee recommended including concepts learned from the early experience in lung continuous distribution.  

American Society of Transplantation | 09/15/2023

The American Society of Transplantation (AST) is generally supportive of what is outlined in the concept paper, “Continuous Distribution of Hearts Concept Paper,” and offers the following comments for consideration:

• The AST commends the careful deliberation about the benefits and potential harms of including post-transplant survival as an attribute. The OPTN Heart Transplantation Committee (Committee) raised reasonable questions about the appropriateness of including this metric without a well-validated model. However, it is not clear from the concept paper why current SRTR performance models are sufficient for assessing heart program performance, but insufficient to serve as a post-transplant survival component of the heart composite allocation score.

• Regardless, AST supports the Committee’s suggestion that the framework under development can be modified eventually to consider inclusion of a well-established and validated metric, and that such an approach would be preferable to including post-transplant survival in the initial policy proposal without robust support for the metric itself.

• The AST recommends in addition to waiting time accrued with an implanted VAD or LVAD, the Committee consider including a pathway for candidates with demonstrated complications or intolerance to the implanted device.

• The AST strongly supports incorporating in the initial version of the heart continuous distribution policies the congenital heart disease and hypertrophic and restrictive cardiomyopathy recommendations in the current guidance document for heart status exception requests. The AST urges the Committee to consider other opportunities to move away from the current exception dependent practice.

• With regards to placement efficiency, maintaining some semblance to the current system which considers distance between the donor and transplant hospital seems reasonable.

• The AST wants to underscore the need to capture nuances in the point-based framework which may impact pediatric heart transplant recipients such as size discrepancy, or post-transplant survival, so that attributes which will impact organ access for pediatric patients get adequate weightage or priority.

• In response to the specific questions included in the proposal:

Are the attributes the Committee has identified for inclusion in the first version of the continuous distribution of heart allocation framework appropriate? Do you agree with the Committee’s decision to include each attribute in the first version of Heart CD? Why or why not?

• The AST believes that attributes created (medical urgency, post-transplant survival, reducing biological disadvantages, patient access and placement efficiency) are appropriate, albeit with anticipated challenges. Some anticipated challenges include the following:

  • Medical urgency – programs may ask for more exceptions as this is a major driver of where the patient ends up on the allocation list. As a result, exception requests may be used to increase priority of candidates with lower degree of medical urgency.1 Furthermore with 95% approval rate of exception requests, without further monitoring and optimization of exception request process, the CD model may be further manipulated.2 To incentivize durable LVADs, waitlist time with durable LVAD should be included in the composite allocation score as outlined in the concept paper. We would also emphasize that choosing variables that are truly reflective of medical urgency (Cr, disease entity, bilirubin, etc.) rather than just method of support will help further risk stratify and reduce gaming. This validated method is currently included in the new French Allocation system.3
  • Post-transplant survival – see below
  • Reducing biological disadvantages- While there is a need to help those at a disadvantage, heart transplant centers vary on their definition of sensitization and may not use the same lab for cPRA calculation. Highly sensitized also varies in definition with cPRA anywhere between 20-80%, depending on the transplant hospital or study. In order to add this, the AST agrees the proposed method of listing unacceptable antigens to obtain points for desensitization is likely the best approach for this particular component.
  • Patient access – agree with this component
  • Placement efficiency – agree with this component

Should the Committee create an attribute for post-transplant survival for inclusion in the first version of the continuous distribution of heart allocation framework? Why or why not? What, if any, predictive models should the Committee consider for use?

• The AST believes that post-transplant survival is an appropriate attribute to consider; however, as stated above, it should not be included in the first version of heart continuous distribution allocation policies. Post-transplant survival is variable based on patient co-morbidities, in hospital status 1-3, single vs multi-organ transplants, and the transplant program’s level of expertise (e.g., certain centers may do more congenital cases that others or simply high volume vs low volume transplant centers). As such, there should be a guidance document first advising which components would be included in the incorporation of a post-transplant survival score and then integrate the component in a follow up version.

• The new French Allocation System accounts for donor and recipient variables, rendering a Transplant Risk Score (TRS) which factors into their allocation to assess for post-transplant survival (the score has been prospectively validated). The TRS includes seven recipient factors: age, indication for transplantation, previous cardiac surgery, diabetes mellitus, mechanical ventilation, GFR, and total bilirubin level and two donor factors: age and gender.3 Perhaps premature, but incorporation of more donor and recipient variables should be considered to help optimize patient outcomes.

Considering the individual attributes, what information should the Heart Committee use to evaluate success toward the outcome of that specific attribute?

• Medical Urgency: death on waitlist, increase in status requiring upgrades or additional tMCS, removal of waitlist for further deterioration requiring durable MCS or palliation.

• Post-transplant survival: not in this version until more data is available.

• Reducing biological disadvantages: rate of highly sensitized patient time to transplant or time on waitlist, modification of listed unacceptable antigens based on waitlist time.

• Patient access: assess each transplant rate of socioeconomic barriers (race, ethnicity, insurance status, etc.) Beyond the medical urgencies which are obvious are transplant centers offering care to patients of all socioeconomic challenges or are some centers better than others?4

• Placement Efficiency: Assess why hearts are turned down – if centers frequently turn down offers primarily due to distance and worry for post-transplant outcomes – is more research and technology optimization that allows broader sharing necessary?

From the patient, donor, family perspective, what do you consider to be the most important factors for allocating donor hearts?

• Allocation of the right heart at the right time without manipulation of medical urgency; including more rigorous review and selective approval of medical exception requests.


1. Johnson DY, Ahn D, Lazenby K, et al. Association of high-priority exceptions with waitlist mortality among heart transplant candidates. J Heart Lung Transplant. 2023;42(9):1175-1182. doi:10.1016/j.healun.2023.05.009

2. Alam A, Hall S. Navigating the rough seas of heart allocation. J Heart Lung Transplant. 2023;42(9):1183-1184. doi:10.1016/j.healun.2023.05.021

3. Dorent R, Jasseron C, Audry B, et al. New French heart allocation system: Comparison with Eurotransplant and US allocation systems. Am J Transplant. 2020;20(5):1236-1243. doi:10.1111/ajt.15816

4. Chouairi F, Fuery M, Clark KA, et al. Evaluation of Racial and Ethnic Disparities in Cardiac Transplantation. J Am Heart Assoc. 2021;10(17):e021067. doi:10.1161/JAHA.120.021067

View attachment from American Society of Transplantation

Anonymous | 09/14/2023

I do believe a point system will work efficiently with the limited amount of information I have seen in presentations. It is hard to understand the medical urgency portion since the cardiology community does not have a single survival calculation that accounts for all cardiology patients. The survival calculations have changed and grown over the years, but they don't take into consideration a lot of factors like inotropes, LVAD's or newer medications.

I don't think distance should matter as long as the center can get there.

I do believe sensitized patients should receive more points since their donor pool is limited and end up having to wait much longer for a suitable organ match.

I do believe LVAD patients should receive more points; the current system has not benefited LVAD's until they have an issue - even the 30 day LVAD time is not allowing for a suitable match most times.

I do not believe the number of years you are predicted to live after should have any bearing on the organ you are offered, unless you are over 70; we should value our older community in their 60's more - some could live 15+ years.

I am curious to see a more in-depth explanation of the allotment of medical urgency points.

American Society for Histocompatibility and Immunogenetics | 09/14/2023

The American Society for Histocompatibility (ASHI) and its National Clinical Affairs Committee (NCAC) appreciate the opportunity to provide feedback around the criteria or attributes that will be used for continuous distribution. ASHI supports applying the most weight for medical urgency, candidate biology, and factors associated with post-transplant graft longevity.

View attachment from American Society for Histocompatibility and Immunogenetics

Region 5 | 09/13/2023

Attendees commented that continuous distribution allocation is a good goal, offered strong support for the paper, and said this is an interesting concept to increase heart transplants. Another attendee recommended to include a weighting of HLA matching, because data suggest there is better long term survival when there are 0 or 1 DR mismatches.

OPTN Pediatric Transplantation Committee Meeting | 09/13/2023

The OPTN Pediatric Transplantation Committee thanks the OPTN Heart Transplantation Committee for their update and for the chance to provide feedback. The Committee asks the Heart Transplantation Committee to keep the following items in mind as it further works to develop continuous distribution. 

First, the Committee recommends exploring options for rating scales for the pediatric attribute. While all children deserve allocation priority, there are specific considerations for patient access and waitlist mortality that may be better captured with the ability to include age and weight in the allocation scheme for pediatric candidates. Also, the Committee recommends exploring including size matching within the allocation scheme, perhaps by using total cardiac volume as a measure. 

Second, the Committee is very interested in the transition and mapping of current medical urgency to a continuous scale in which each condition and the associated waitlist mortality falls somewhere on the curve. This represents a large change in how medical urgency will work for pediatric candidates, and it is important for the Heart Committee to model how these pediatric urgency points will sort against other children and also against adults. An increase in CAS points may not translate directly to an increase in transplants for children, especially for those children who may receive less medical urgency points than they do currently via the current status system, so this should be modeled. The Committee agrees with the decision to include priority for congenital heart conditions within the medical urgency attribute, but encourages the Committee to consider the differences between varying congenital conditions in terms of urgency and mortality risk. 

The Committee is very interested in being a part of these ongoing conversations in a collaborative manner with the Heart Committee, and looks forward to participating in associated Workgroups and discussions.

Anonymous | 09/12/2023

Thank you for the hard work so far. The proposed attributes are appropriate for further discussion. I agree that wait time should be further examined to include time on a VAD as well as the total wait time since listing, although this should be to help with tie breakers and not a means to prioritize over sicker patients. Priority for living donors should be considered as well.

Region 11 | 09/12/2023

A member commented that they support all allocation efforts that improve the efficiency and efficacy of utilization for donated hearts; this consideration should be assessed for all potential allocation changes.

OPTN Ethics Committee | 09/07/2023

The OPTN Ethics Committee thanks the OPTN Heart Transplantation Committee for their work on this update and for the opportunity to provide input. The Committee offers the following feedback regarding the prior living donor attribute, prioritization of sensitized candidates, and inclusion of an attribute for post-transplant survival in the first iteration of continuous distribution.  

First, the Committee asks the Heart Committee to carefully consider the prioritization of prior living donors (PLD) in the PLD attribute. While the Ethics Committee supports incentivizing and protecting living donors, members noted concern that giving extra points to prior living donors in the heart allocation system may affect populations unequally, especially minority and marginalized populations that typically have lower rates of living donation. Data on how many prior living donors were listed on the heart waitlist in a given period of time would be helpful in evaluating the impact of this attribute. Further, while there is a strong ethical justification for giving priority to living kidney donors who wind up on the kidney waitlist, giving priority to living donors who are listed for a different organ than they previously donated may require additional consideration. The Committee notes Members ask the Heart Committee to keep in mind transparency and public perception when developing this attribute. The Committee agrees it is a noble goal to support living donation, but recommends a limited approach to this attribute noting equity concerns.  

Second, the Committee supports prioritization of sensitized candidates in heart continuous distribution. Sensitization is a paradigmatic example of biological disadvantage. A commitment to distributive justice requires that patients of similar need have an equal opportunity to benefit from transplant. In addition, sensitization is more common among women and racial and ethnic minorities. Considering sensitization promotes equity by reducing biological disadvantages and addressing some structural barriers to heart transplantation. Inclusion of additional allocation points for sensitized candidates will also allow centers to consider listing very highly sensitized patients (cPRA>80%), who may previously have been declined because of concern for waitlist mortality. It may also shorten the wait time of sensitized candidates. Consideration of sensitization in allocation meets regulatory and ethical commitments to justice and access to transplantation. 

Third, the Committee in principle supports the inclusion of an attribute for post-transplant survival in the first version of continuous distribution, while acknowledging the logistical challenges. A commitment to utility—maximization of net benefit—requires considering survival before and after transplant. There are both logistical concerns and concerns about potential impact on organ acceptance. The logistical challenges of developing a de novo model should not necessarily, from an ethics perspective, override the opportunity to restructure heart allocation to better align with community priorities and utility considerations. An incremental approach to Heart CAS risks multiple points of disruption in allocation policy revision. It also forgoes an opportunity to begin collecting longitudinal data relevant to this attribute. Given uncertainty around accuracy, if the Heart Committee proceeds with a post-transplant survival metric, transparency requires acknowledging the potential for unintended consequences as well as plans for monitoring and updating the metric attributes. 

Anonymous | 09/06/2023

The current system is not broken. Its limitations are accentuated by organ scarcity. I suggest some minor adjustments to address the objectively unfair aspects of the current system. This could include: 1) giving a small bump to the type O patients, 2) eliminating the hard mileage cutoff (but a continuous distance score would favor local programs), 3) addressing the highly sensitized patient (be careful with #3 because there may be ways of gaming this). Trying to get too cute with the CAS, then some programs will game it (like US News and World Report rankings).

Northwestern Memorial Hospital | 09/06/2023

Support the concept overall.

Suggest for the first iteration of the proposal that only the following attributes be included:
• Medical urgency
• Reducing biological disadvantages
• Patient access
• Placement efficiency

Suggest NOT including post-transplant survival in the first proposal iteration, as there is no adequate data on this category (i.e., as indicated by the Committee [page 19 of the concept paper], “there is no existing heart-specific model that could be readily adapted for inclusion in continuous distribution”). Also, as mentioned by the Committee, the use of this metric may impact access to transplant for some potential candidates (e.g., higher risk candidates) if the program believes that its program-specific score will be impacted by a post-transplant survival metric. Finally, it is fairly colinear with medical urgency.

Kambiz Ghafourian, MD; Duc Thinh Pham, MD; and Jane Wilcox, MD on behalf of the Northwestern Memorial Hospital Heart Transplant Program

Andrew Kao | 09/02/2023

1. Proximity of donor and recipient hospital has to be given more priority than just 5% as in the lung continuous distribution model. I am very concerned about increasing travel distance and costs as well as surgeon and procurement staff safety.

2. Agree that blood group O recipients be given more priority - could we allocate organs to blood type identical recipients through the "statuses" before going to a blood type compatible recipient? So and O organ would go through the O recipient list through the various acuity statuses before going to B, A and AB.

3. Disagree with including inactive time in the wait time variable - this would encourage programs to list patients who are not quite ready for transplant to accrue time. We had this problem in the late 1980s when status 2 time was added to status 1 time which precluded acutely ill patients from getting organ offers.,

4. Agree with giving some weight to highly allosensitized recipients but need to decide if a categorical or continuous variable is more appropriate and decide what "cutoff" percentage should be considered. Perhaps 80% or higher cPRA should be given prioprity.

5. LVAD waiting time is a difficult issue. Agree that there should be a "cap" to how long some one is on a LVAD - so if someone has had a LVAD for 7-10 years probably are stable enough they do not need further credit for their waiting time. Is it possible to add priority points per annum of wait up until a certain point?

6. Thank you for working on this very complex issue.

Region 2 | 09/01/2023

This was not discussed during the meeting, but attendees were able to submit comments with their sentiment. One member noted excitement in reviewing and recognizing increased utilization of organ distribution. Another member expressed supporting the hypertrophic cardiomyopathy and congenital populations. Continuous distribution could be especially beneficial for those patients. Continuous may not be as beneficial for Ventricular Assist Device (VAD) patients, as this therapy has gotten much better with regard to long-term outcomes. However, there should be higher listing statuses for VAD complications or VAD intolerance, like bleeding or infection. The other patient population that could benefit from continuous distribution would be patients with end stage coronary disease with intractable angina. Currently, it has been a struggle with trying to get these patients upgraded and transplanted.

Region 4 | 08/29/2023

One attendee commented that the committee may want to consider right ventricular dysfunction in the face of a left ventricular assist device. Another attendee commented that the committee should learn from the lung continuous distribution implementation. They added that from an OPO perspective, the lung allocation does not factor in geography or donation after circulatory death donors (DCD) adequately, resulting in an unnecessary burden for OPOs and Transplant Centers. They went on to comment that while geography should not be the primary driver of allocation, it needs to considered more thoroughly. One attendee commented that medical urgency needs to be determined by the medical condition of the listed patient rather than the device chosen to support them. Utilizing more data elements that truly reflect severity of condition (estimated glomerular filtration rate (eGFR), creatinine, sodium, etc.) will be needed to balance out the device abuse that has become the new normal.

OPTN Transplant Coordinators Committee | 08/28/2023

The OPTN Transplant Coordinators Committee thanks the OPTN Heart Transplantation Committee for their work and for the opportunity to comment on this proposal.

A member agreed with the updated diagnoses, but recommended growth parameters be added to the listing status. Another member agreed and mentioned that the proposal appears to realign pediatric statuses to be more like the adult statuses. However, the member feels that pediatric durable ventricular assist devices (VADs) are at a much higher advantage than other pediatric VADs that are not dischargeable and is unsure if pediatric wait time for durable VAD is as relevant. The member also said that candidates who are non-dischargeable from the hospital should get some priority in the status. The member said the Committee should consider giving extra points to members who are transplanted as a pediatric patient but need to be re-transplanted as an adult.

A member stated that size matches are an important consideration when looking at donors at their center and asked if it would be applied as an attribute since the distance attribute weight will determine the significance of travel and how perfusion machines can impact that. 

A member asked about the timeline for the project and the need to be as transparent as possible with the transplant community. A member said there is benefit in not being the first organ system to move to the continuous distribution model of allocation, as this allows the committee to learn from previous committees. A member voiced their concern with the timeline, specifically that there will be no changes to the pediatric statuses in the meantime. Another member agreed, saying that pediatric candidates need changes sooner and not in four years.

Matthew O'Connor | 08/25/2023

I welcome this re-assessment of heart allocation and appreciate the thoughtful approach put forward by the Committee in this concept paper. I have a few thoughts:
-I would be reluctant to put post-transplant survival metric into the CAS at this point given that we do not have a validated model for survival, as others have pointed out. I am not sure that such a model can ever be reliably generated given that survival varies across centers, even after risk adjustment. Additionally, within various subsets of CHD diagnoses there are differences in survival that are not captured on current risk adjustment models used by UNOS/SRTR.
-Older adolescents on with DCM on VAD have a distinct advantage in the current allocation system, as they are highest priority and can access both the adult and pediatric donor pools. It is not clear that this advantage is fair, both to adults and pediatric potential recipients. I question whether a 17 year old patient of adult size really needs an increase in the CAS purely based on age. I would be interested if the Committee would consider some factor incorporating the patient's size can be factored into the pediatric "benefit" such that the benefit is scaled according to both age AND size.
-Although there is valid criticism that the pediatric 1A status encompasses patients that have very different risk profiles, segmentation of the pediatric 1A group (which will be a result of adopting CAS) comes at the risk of leading programs to change their behavior to suit the stratification system. The increase in use of Impella in adults awaiting transplant is a good example of this.
-Increasing MCS use is reducing pre-transplant mortality in most groups, even infants with CHD. Thus, pre-transplant mortality should be weighted less heavily than wait time in the heart CAS.

Ryan Davies | 08/23/2023

There are clearly multiple advantages to the transition to continuous distribution from the current tiered system, especially in children where the current three-tiered system is inadequate. I would favor the use of some measure of post-transplant outcome, particularly because it may have the potential to limit the application of temporary support devices with less positive impact on post-transplant outcomes than placement of more durable VADs. It is unclear if alterations in allocation can truly impact the high waitlist mortality among small children awaiting transplant, because there are simply not enough organs, and it is not (generally) that there are a large number of relatively well infants taking organs from those who are sickest. Trying to identify metrics in these patients that truly mark them as sicker would be valuable. The balance between dictating clinical care and appropriately stratifying patients based on the support they require is difficult, overall waitlist outcomes have improved in this population largely related to increased and improved outcomes with VADs, so ensuring that the allocation rules do not push patients away from VADs and lead to patients limping to transplant would be helpful. I look forward to seeing the proposal for continuous distribution as it moves forward.

Mike McCulloch | 08/22/2023

A three status system is clearly inadequate for the heterogeneous population of pediatric patients awaiting heart transplantation. Composite allocation scoring would allow for a more nuanced, representative stratification which should decrease waitlist mortality and potentially mitigate the disadvantages inherent in candidates who are allosensitized, have O blood type, etc. Clearly the biggest challenge will be including and weighing the appropriate attributes to achieve these goals, which will require continuous reassessment to ensure these outcomes are achieved. Several potential issues come to mind which I am certain are already being considered, but are worth stating. I worry about disadvantaging transplant centers whose patients may not get 'credit' for certain attributes. For example, patients could theoretically lose CAS for things such as cPRA if their listing institutions are willing to transplant across a positive crossmatch or post-transplant outcome CAS if they are willing to tolerate slightly longer donor ischemic times because of comparable institutional outcomes. Additionally, measures should be taken to discourage leaving patients on ECMO (as opposed to converting to a VAD) in order to achieve higher medical urgency scoring. In other words, it is important for institutions/ candidates to not be penalized for practicing current standard of care. Overall, I strongly believe this is the right thing to do, but it will require a completely transparent process to ensure universal acceptance.

Brian Feingold | 08/21/2023

I support this continuous distribution (CD) concept paper for heart transplantation. Implementation of CD should get rid of the somewhat arbitrary cutoffs around distance that are currently used. Further, pediatric heart transplantation urgency strata are too broad, specifically status 1A, and CD should allow for enhanced prioritization for allocation on features associated with high risk of waitlist mortality rather than time accrued at urgency status. Incorporation of a post-transplant survival metric into CD should not be undertaken at this time since there is no well established metric for this that currently exists. Much work will need to be devoted before implementing such a metric for heart allocation given the broad spectrum of recipients (infants to adults, individuals with congenital heart disease to those with non-CHD indications for transplantation, etc.). I believe introduction of this on the first pass would introduce too much change too quickly. It is better left for subsequent revisions of heart CD. I am in favor of looking further at blood type and HLA allosensitization as biological factors to be considered with organ offers.

Luke Masha | 08/15/2023

I strongly oppose this proposal.

It recommends a scoring of donor and recipient factors to create a composite allocation score and this subverts the transplant evaluation process completely. Plus it introduces unfair biases and hampers programs from taking necessary risks for individual patients as needed (for example taking a heart that may have a slightly long ischemic time or is has a sizing abnormality for a critically ill patient). I believe that individual transplant centers will always do a better job at these things that calculated risk scores and thus am opposed to a risk score superceding transplant decisions and affecting the likelihood of transplant for patients. I am generally in favor however of adding a prioritization to the allocation system for highly sensitized patients, something this proposal seems to suggest it wants to do. The current system that only factors in medical urgency and waitlist time seems fair.

Thus I strongly oppose this proposal.

Anonymous | 08/09/2023

excellent concept. it's functionality will be determined by the exact method of calculation of these variables and the weight they carry.

Anonymous | 08/07/2023

Why not work towards a prospective randomized control trial validating that any alternative approach to the current system is superior when it comes to overall patient outcomes. Executing policy without evidence creates a perpetual system that may be designed out of goodwill but a potential disaster for patient outcomes when its at such a large scale.