Impact of Temporary Percutaneous Mechanical Circulatory Support Before Transplantation in the 2018 Heart Allocation System

Objectives: This analysis sought to investigate the waitlist and post-transplant outcomes of individuals bridged to transplantation by using temporary percutaneous endovascular mechanical circulatory support (tMCS) through a status 2 designation (cardiogenic shock and exception).

Background: The 2018 donor heart allocation policy change granted a status 2 designation to patients supported with tMCS.

Methods: Adult patients in the United Network for Organ Sharing registry after October 18, 2018 who received a status 2 designation for tMCS were included and grouped by their status 2 criteria: cardiogenic shock with hemodynamic criteria (CS-HD), cardiogenic shock without hemodynamic criteria before tMCS (CS-woHD), and exception. Baseline characteristics, waitlist events (death and delisting), and post-transplant outcomes were compared.

Results: A total of 2,279 patients met inclusion criteria: 68.6% (n = 1,564) with CS-HD, 3.2% (n = 73) with CS-woHD, and 28.2% (n = 642) with exceptions. A total of 64.2% of patients underwent heart transplantation within 14 days of status 2 listing or upgrade, and 1.9% died or were delisted for worsening clinical condition. Among the 35.8% who did not undergo transplantation following 14 days, only 2.8% went on to receive a left ventricular assist device (LVAD). The 30-day transplantation likelihood was similar among groups: 80.1% for the CS-HD group vs 79.7% for the exception group vs 73.3% for the CS-woHD group; P = 0.31. However, patients who met criteria for CS-woHD had 2.3-fold greater risk of death or delisting (95% CI: 1.10-4.75; P = 0.03) compared with CS-HD patients after multivariable adjustment. Pre-tMCS hemodynamics were not associated with adverse waitlist events.

Conclusions: The use of tMCS is an efficient, safe, and effective strategy as a bridge to transplantation; however, patients with CS-woHD may represent a high-risk cohort. Transition to a durable LVAD was a rare event in this group.