Thursday, April 23, 2020

Gaming organ allocation: Heart failure treatment responds to changes in the priority rules for heart transplants

Recent changes in the allocation of deceased donor hearts for transplantation have focused on what kinds of mechanical interventions a patient has.  And as choice of alternative interventions has changed priorities for donation, cardiologists have responded by changing the interventions they choose.

Several articles in JAMA Cardiology speak to this and related matters, and here's an editorial describing the issue:

Anticipating a New Era in Heart Transplantation
Clyde W. Yancy, MD, MSc1,2; Gregg C. Fonarow, MD3,4
JAMA Cardiol. Published online April 15, 2020. doi:10.1001/jamacardio.2020.0611

The first paragraph gives this capsule history:

"The 50th anniversary of heart transplantation was celebrated in 2018. During those 50 years, heart transplantation as treatment of advanced heart failure evolved from a heroic intervention with uncertain outcomes to a guideline-directed treatment appropriate for selected patients to restore quality of life and to improve survival. Today, 1-year survival after heart transplant is nearly 90%, and the conditional half-life after heart transplant is now 13 years.1 Those robust outcomes reflect myriad breakthrough initiatives, including the definition of brain death; introduction of routine endomyocardial biopsy for rejection surveillance, development of potent immunosuppressive therapies, particularly those inhibiting calcineurin and in turn interleukin 2 production, and advances in therapies to support the failing ventricle, especially mechanical circulatory support devices. For more than 2 decades, the number of heart transplants performed in the United States has been approximately 2000 per year and, having recently increased, was 3551 in 2019.2 Taken together, the observed early and late benefits of heart transplant punctuate an incredible journey from heretical concept to clinical standard of care. The courageous pioneer physicians and especially the early patients who faced overwhelming risks are revered for establishing a foundational pillar in the care of patients with advanced heart failure. It is reasonable to assert that after 50 years, heart transplantation is a well-established success poised for the next era."

They then turn their attention to ways in which cardiologists have responded to changes in the deceased donor allocation system:

"Three articles in this issue of JAMA Cardiology further address new challenges in the process of care improvement for heart transplantation, some of which we think may require urgent attention.

"The first of these articles, by Hanff and colleagues,7 evaluated changes in the use of mechanical circulatory support under the auspices of new organ allocation rules introduced in October 2018 by the Organ Procurement and Transplantation Network. The new system was intended to redirect available donors to those patients of greatest need. The original status IA category was partitioned into 3 categories, and the original status IB category became category 4. A patient with advanced heart failure supported with a left ventricular assist device (LVAD) without LVAD-associated complications became a status 4 candidate. A similar patient with advanced heart failure experiencing manageable LVAD-associated complications became a status 3. Status 2 now captures those patients with LVAD device malfunction who may be facing eminent demise or need for LVAD replacement, whereas status 1 captures patients with life-threatening arrhythmias or patients being supported with venoarterial extracorporeal membrane oxygenation (VA-ECMO). Evaluating data through June 2019, Hanff and colleagues7 noted an abrupt increase in the use of VA-ECMO support that was temporally associated with implementation of the new system. Concomitantly, LVAD support for advanced heart failure in patients awaiting heart transplant abruptly decreased from 35.1% before implementation of the new rules to 24.5% after their implementation."

Finally, they also consider center variability to understand what happens to patients when a proffered heart transplant is declined:

"In another article in this issue of JAMA Cardiology, Choi et al10 evaluated data in the US National Transplant Registry between 2007 and 2017 with the intention to assess transplant center variability in donor organ acceptance. The evaluable data emanated from 93 transplant centers and encompassed 19 703 donors and 9628 candidates, with 32% of the donors accepted as first-ranked candidates. After adjustment for pertinent donor, candidate, and geographic covariates, the center variability in acceptance rates was quite remarkable at 12% to 62%. For every 10% increase in center acceptance rate, waiting-list mortality decreased by 27%. Those centers with lower acceptance rates experienced higher waiting-list mortality among candidates listed for a heart transplant..."


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