Impact of mechanical circulatory support on donor heart allocation: past, present, and future

Abstract

The United Network for Organ Sharing (UNOS) recently revised its heart allocation policy to address numerous shortcomings of the previous system. Implemented in 2018, the changes sought to reduce waiting list mortality, clearly define urgency status based on objective physiologic variables, decrease exemption requests, and introduce geographic modifications to ensure organ distribution favors the highest urgency candidates. In large part, UNOS policy revisions were driven by the growing use of continuous flow left ventricular assist devices (CF-LVADs) and the relevant device complications that led to an unacceptably high number of status exemptions. The new 6-tiered system assigns a comparatively lower urgency status to patients supported on CF-LVADs and higher urgency to patients supported on short-term mechanical circulatory assist (MCA) such as extracorporeal membrane oxygenation (ECMO) and intraaortic balloon pump (IABP) counterpulsation. LVAD use as bridge to transplant (BTT) therapy increased steadily throughout the preceding decade due to technological improvements and increased physician familiarity, but the recent policy changes introduce incentives for physicians to withhold this life-saving therapy in order to achieve higher urgency status for their patients. This paper will explore the technological evolution of MCA and the pertinent clinical trials that have led to their FDA approval as BTT and destination therapy. A review of the inception and development of the donor allocation system will be provided before examining available post-policy outcome data. Finally, we will highlight successes and shortcomings of the implemented changes before commenting on areas to potentially expand upon the existing policy.

Characterizing Adaptive Changes and Patient Survival After 2018 Donor Allocation Restructuring: A UNOS Database Analysis

“…Understanding the impact of policy revisions on observed trends in device utilization and posttransplant survival requires an appreciation of how the status criteria revision has produced incentives that play a significant role in patterns of device utilization. 24…”

Innovations and challenges across the heart failure spectrum

“…In patients with refractory symptoms advanced heart failure therapies and palliative care should be considered. Tatum et al [19] describe the amazing evolution of durable mechanical support that motivated changes in the heart allocation policy and the consequences of those changes in the future of durable mechanical support.…”