Impact of 2018 UNOS Heart Transplant Policy Changes: Key Points

Maitra NS, Dugger SJ, Balachandran IC, Civitello AB, Khazanie P, Rogers JG.
Impact of the 2018 UNOS Heart Transplant Policy Changes on Patient Outcomes. JACC Heart Fail 2023;11:491-503.

The following are key points to remember from a state-of-the-art review on the impact of the 2018 United Network for Organ Sharing (UNOS) heart transplant policy changes on patient outcomes:

  1. Introduction: In 2018, the UNOS policy for heart transplantation (HT) changed from a three-tier to a six-tier system based on medical urgency. The intent of the change was to better stratify patients based on expected waitlist mortality using objective criteria, give higher priority and reduce waitlist time for patients most at risk, reduce overall waitlist mortality, and enable broader organ sharing. This new policy has led to significant changes.
  2. Listing Practices: In both the previous and current policy eras, the majority of patients are listed in the highest statuses. In the new system, patients in the old status 1A are stratified into statuses 1-3. Listings for these groups have increased (approximately 25% in status 1A, approximately 35% in statuses 1-3 currently). This has also resulted in an increase in patients transplanted at these highest priorities (68% vs. 78%).
  3. Waitlist Mortality: Compared to the prior policy, the new HT policy better stratifies transplant candidates by risk of waitlist mortality, with status 1 patients having the highest risk (139 deaths/100 patient-years) and status 6 having the lowest risk (3.9 deaths/100 patient-years). While overall waitlist mortality after the policy change appears similar to reduced based on different analyses, further studies are needed.
  4. Waitlist Times: Median waitlist times have decreased with the new HT policy, going from 112 days to 39 days. Patients supported with durable left ventricular assist devices (LVADs) also have shorter median waitlist times (139.5 to 37 days), although the majority were higher priority than status 4. Rates of transplant for patients with LVADs at status 4 declined.
  5. Post-transplant Outcomes: Reducing waitlist mortality by transplanting higher acuity patients may impact post-transplant outcomes. Current analyses are conflicting, although data generally suggest that short- and intermediate-term post-transplant mortality is similar to the previous era.
  6. Temporary Mechanical Circulatory Support Use: Compared to the prior era, use of temporary mechanical circulatory support (MCS) as a bridge to transplant increased with the new policy change, which includes veno-arterial extracorporeal membrane oxygenation (VA-ECMO) (1.8% vs. 2.7%), intra-aortic balloon pump (IABP) (5.3% vs. 10.3%), and biventricular support (1.3% vs. 2.1%). Use of VA-ECMO, IABP, and percutaneous temporary LVADs (e.g., Impella devices) as a bridge to transplant in the current policy era has been associated with decreased time to transplant, increased rates of transplant, and decreased waitlist death or deterioration. Analyses of post-transplant survival have mixed results, but generally suggest similar survival before and after the policy change.
  7. Durable LVAD Use: Durable LVAD implants have decreased in the new policy era. Studies suggest that rates of transplantation with LVAD support are similar or have decreased. Most transplants occur as status 2 or 3. Waitlist mortality is similar between the two eras. One-year post-transplantation survival appears to be similar or reduced, which may reflect use of higher-risk donors, longer ischemic times, and LVAD-associated complications driving higher listing priority.
  8. Donor Characteristics: Broader organ sharing across regions of the United States, especially for the highest status HT candidates, was a goal of the new HT policy. Distance between donor and recipient centers, as well as average donor organ ischemic times (3.0 vs. 3.4 hours), has increased in the current era. This may have broad implications on post-transplant outcomes and continued monitoring is needed.
  9. Specific Cardiomyopathies and Adult Congenital Heart Disease: For patients with hypertrophic and restrictive cardiomyopathy, the new HT policy has resulted in shorter waitlist times and increased rates of transplant. For patients with congenital heart disease, waitlist times and rates of transplant appear similar. Use of temporary MCS has also increased in these patient populations.
  10. Multi-Organ Transplant: Patients listed for multi-organ transplant in the new HT policy are placed in status 5, with opportunity to be listed at a higher status based on worsening of their cardiac condition. Similar to isolated heart transplant, increases in use of temporary MCS (ECMO, IABP) and intensive care unit–level care were noted for patients listed for multi-organ transplant. Since implementation of the new policy, post-transplant survival for combined heart-lung and heart-liver recipients is similar. Patients receiving heart-kidney transplant appear to have higher rates of post-transplant dialysis and increased mortality.
  11. Future Directions: Many of the intended goals of the new HT allocation policy were met. However, future work and changes will need to address important issues such as continuing to improve risk stratification and allocation, addressing the high number of exception requests, addressing changing durable LVAD and temporary MCS use, considering strategies for highly sensitized patients, and reducing health care inequities.

Clinical Topics: Cardiac Surgery, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Cardiac Surgery and CHD and Pediatrics, Cardiac Surgery and Heart Failure, Congenital Heart Disease, CHD and Pediatrics and Interventions, CHD and Pediatrics and Prevention, CHD and Pediatrics and Quality Improvement, Acute Heart Failure, Heart Transplant, Mechanical Circulatory Support, Interventions and Structural Heart Disease

Keywords: Cardiac Surgical Procedures, Cardiomyopathies, Critical Illness, Extracorporeal Membrane Oxygenation, Heart Defects, Congenital, Heart Failure, Heart Transplantation, Heart-Assist Devices, Intra-Aortic Balloon Pumping, Ischemia, Kidney Transplantation, Liver Transplantation, Renal Dialysis, Risk Assessment, Survival

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