The Heart Track: A Summary of the CEOT Breakout Sessions
The AST’s fourth Cutting Edge of Transplantation (CEOT) meeting included a separate Heart Track, co-sponsored by Cedars-Sinai Heart Institute, to engender review and discussion of important issues being faced in the field of heart transplantation under the aegis of the "Resolving the Organ Shortage: Practice, Policy, Politics" theme of the conference.
Evan Kransdorf, MD, PhD; Jon Kobashigawa, MD
In the first session, "Increasing the Donor Heart Pool":
Tom Mone from the organ procurement agency (OPO) OneLegacy opened the session by offering strategies to expand heart donation. He highlighted the importance of increasing public awareness of the benefits of transplantation, as well as establishing strong lines of communication between the OPO and its transplant centers.
Next, Evan Kransdorf, MD, PhD from Cedars-Sinai Heart Institute discussed mechanisms of immune system activation that occur after brain death and presented pre-clinical data on potential therapeutic strategies to mitigate this activation.
This was followed by Darren Malinoski, MD from Oregon Health & Science University, who discussed his work showing that meeting pre-established donor management goals leads to improved donor heart utilization.
Sean Pinney, MD from Icahn School of Medicine then reviewed the data on the benefits of utilizing thyroid hormone and corticosteroids during heart donor management.
Following this session, Igor Gregoric, MD from the University of Texas Health Science Center discussed risk factors that define an “extended criteria” donor heart.
Finally, Abbas Ardehali, MD from UCLA Medical Center discussed the basis of ex vivo heart perfusion as well as his experience with the TransMedics Organ Care System, which will be undergoing further study as part of the EXPAND Heart Trial. In addition, it was exciting to hear that ex vivo heart perfusion is just recently being used in donation after cardiac death (DCD) patients, which could potentially increase the donor heart pool by as much as 30%.
The Heart Track reconvened the next day with its second session, "Donor Heart Selection":
David Baran, MD from Newark Beth Israel Medical Center started the session off with a review of donor risk factors for adverse outcomes, as well as his analysis showing a lack of relationship between a donor heart’s sequence number and outcome.
Next, Monia Colvin, MD from the University of Michigan reviewed the data regarding recipient risk factors for adverse outcomes.
The session took a brief surgical interlude when Michael Acker, MD from the University of Pennsylvania discussed surgical considerations in mechanical circulatory support and heart transplantation.
This was followed Jignesh Patel, MD, PhD from Cedars-Sinai Heart Institute who discussed how to assess sensitized patients prior to transplant, and discussed his ongoing clinical trial using eculizumab for sensitized patients undergoing heart transplantation.
Michael Givertz, MD from Brigham and Women’s Hospital then reviewed extant risk scores which can help clinicians support their difficult decision to accept or refuse a particular donor heart for a recipient.
Finally, Kiran Khush, MD from Stanford University discussed her work looking at factors which predict donor non-use, and highlighted the important information that will be gleaned from her prospective study of donor heart utilization that is currently ongoing, the Donor Heart Study.
To conclude the donor selection topic, a panel of expert surgeons, Drs. Fardad Esmailian (Cedars-Sinai Heart Institute), Gonzalo Gonzales (Baylor Medical Center), Valluvan Jeevanandam (University of Chicago) and James Kirklin (University of Alabama at Birmingham) opined on accepting/declining actual donor heart case studies. This was very informative and helped put the previous donor heart selection talks into perspective. There are many factors to be taken into account when evaluating a possible donor heart in regard to a specific recipient. In the end, the decision to accept any donor heart depends on the experience of the transplant team and the risks (in terms of a marginal donor) that the team is willing to take.
The third CEOT session specifically addressed the significant changes for adult heart alocation in the United States proposed by the UNOS Thoracic Committee in January 2016:
This session opened with an overview of the new donor heart allocation tiers by Dan Meyer, MD from the University of Texas Southwestern Medical Center. In the new system, allocation will be prioritized according to six groups, as compared to the current three-group system.
Next, Ulrich Jorde, MD from Montefiore Medical Center reviewed the literature on ventricular assist device complications, elucidating those which should remain as indications for urgent heart transplantation.
This was followed by David Vega, MD from Emory University who discussed the current UNOS regulations regarding the geography of organ sharing and how this would be changed in the new donor heart allocation system.
Heather Ross, MD from Toronto General Hospital then gave the audience an update on the Canadian "4S" system for prioritizing heart allocation to sensitized candidates.
She was followed by Eileen Hsich, MD from the Cleveland Clinic who reviewed populations of heart transplant candidates that are under-represented, such as women, ethnic minorities, and those with restrictive cardiomyopathy.
Finally, this distinguished panel of physicians engaged in a lively discussion of the potential risks and benefits of the heart new allocation system.
With the literature reviewed and concerns raised at the CEOT Heart Track firmly in mind, the AST Thoracic and Critical Care Community of Practice has prepared a response to the new UNOS donor heart allocation proposal. First, with regards to how hearts should be allocated, the AST membership is in favor of a Heart Allocation Score (HAS). Unfortunately, a robust system for allocation is not yet available.
Second, with regards to the new proposal’s prioritization of patients on extracorporeal membrane oxygenation (ECMO), the membership felt that this prioritization could violate the ethical principle of utility since these patients have inferior survival after heart transplant. Furthermore, some members felt that prioritization of candidates on ECMO would lead to an increased utilization of this therapy solely as a means of facilitating heart allocation. Several suggestions were proposed.
Third, with regard to the composition of the new proposal’s tiers, the membership felt that the placement of particular types of mechanical circulatory support (MCS) into tiers 1, 2 and 3 was problematic. Technical expertise and thus MCS types used vary between transplant centers, without a clear body of literature on the optimal strategy. For example, the membership discussed that biventricular Abiomed Impella catheters, biventricular Thoratec Centrimags, or a Syncardia TAH, are all forms of biventricular support, but would lead to different allocation tiers for a transplant candidate. The membership did not feel that the tiers should offer an allocation priority for certain types of MCS; rather, the prioritization should address the underlying risk. Likewise, an intra-aortic balloon pump was not felt to substantiate a higher priority tier over inotropic therapy. Next, with regard to allocation to sensitized heart transplant candidates; the membership felt that these candidates should have an allocation priority. However, the nature of this priority, as well as technical concerns regarding the definition of the sensitized patient, require further study.
Lastly, the membership questioned the doses of inotropes required for qualification of inotropic therapy. Members felt that the doses proposed in the new proposal were excessive, as some patients require inotropes as smaller doses and the risk of complications increases with the dose used. These important discussions in the presence of members from the UNOS Thoracic Committee and members from the SRTR and UNOS had a significant impact on the committee’s thoughts on the new donor heart allocation proposal. As a result of public comment on this issue, the new proposal will not go directly to the UNOS Board of Directors for approval but will be modified according to the discussions held at the CEOT and other forums.
As you can see, the Heart Track was an extremely successful component of this year’s CEOT. We hope to build upon this success in future years, and look forward to seeing how the meeting develops in the future.