Starting in September 2018, the revised UNOS adult heart allocation system goes into effect. This post provides a brief overview of the changes to the medical urgency statuses of mechanical circulatory support (MCS) device recipients and offers additional resources for more information.
Today, heart transplantation is the gold standard for patients suffering from advanced and end-stage heart failure.1 However, the existing United States adult heart allocation system, which is based on medical urgency (those with the highest pre-transplant mortality) and benefit gained from transplantation (those with the highest post-transplant survival potential), faces two major challenges:2
- A rapidly growing transplant waiting list with limited donor heart availability
- Evolving and expanding use of temporary and durable MCS devices to treat advanced and end-stage heart failure
Since the last revision of the heart allocation system in 2005, technological advances in device therapy, improved patient selection criteria and increased clinician experience with device management have resulted in improvements in outcomes for advanced heart failure patients.2 In response to these advances and challenges, the United Network for Organ Sharing (UNOS) created a revised adult heart allocation system that will go into effect starting in September 2018.
The most significant revision to the allocation system is the expansion of the three existing medical urgency statuses (Status 1A, 1B and 2) to six (Status 1 – 6). Under the revised system, patients in the current 1A status have been stratified into three groups of decreasing severity.3
In addition, the revised medical urgency statuses allow for greater distinctions between the different types of MCS devices currently available, including whether a patient is on a temporary or durable MCS device, and whether the patient requires biventricular support or replacement or single ventricular support.2
Key Changes Under the Revised Adult Heart Allocation System
Total Artificial Heart (TAH) Patients
Currently, TAH patients are listed Status 1A while in the hospital, then Status 1B after they’ve been discharged using the Freedom® Portable Driver. Under the new system, TAH patients will be classified as Status 2 and remain Status 2 for as long as they are supported by the device, regardless of their discharge status.
Left Ventricular Assist Device (LVAD) Patients
The current allocation system lists LVAD patients as Status 1B with a discretionary 30 days at Status 1A. This priority listing reflects the reliability and performance of LVADs at the time of the system’s last revision; however, advances have since led to improved long-term outcomes in patients with advanced heart failure awaiting transplantation. UNOS has amended its criteria for LVADs accordingly. Under the new system, all discharged LVAD patients will be Status 4 with a discretionary 30 days at Status 3. LVAD patients experiencing complications, such as pump thrombus or device infection, will be listed as Status 3.
Extracorporeal Membrane Oxygenation (ECMO) Patients
Under the current system, VA ECMO patients are Status 1A indefinitely. When the new system goes into effect, VA ECMO patients will be Status 1 for seven days before dropping to Status 3.
A candidate’s status can only be extended beyond seven days if the transplant program can provide objective evidence to the regional review board (RRB) of both of the following:
- The candidate has demonstrated a contraindication to durable device support
- Within 48 hours prior to the status expiring, the transplant program was unable to wean the candidate from VA ECMO, as evidenced by at least one of the following criteria:
- Mean arterial pressure (MAP) less than 60 mmHg
- Cardiac index less than 2.0 L/min/m2
- Pulmonary capillary wedge pressure greater than 15 mmHg
- SvO2 less than 50% measured by central venous catheter
Patients with Specific Etiologies
Under the new system, congenital heart disease, ischemic heart disease with intractable angina, amyloidosis, restrictive and hypertrophic cardiomyopathy and re-transplant patients will be Status 4.
Download Our Guide
For more information on the revised UNOS adult heart allocation system and how it will impact the medical urgency statuses of MCS device recipients, download our guide here, which provides a more in-depth look at the changes and commentary on how these changes may impact MCS device use.
If you have questions, comments or concerns about the upcoming UNOS changes, or would just like to discuss the topic further, please contact your SynCardia Sales Representative or Clinical Specialist.
²Rao P, Smith R, Khalpey Z. Potential Impact of the Proposed Revised UNOS Thoracic Organ Allocation System. Seminars in Thoracic and Cardiovascular Surgery. 2018;30(2):129-133. doi:10.1053/j.semtcvs.2018.01.001.