The Changing Landscape of Temporary Mechanical Circulatory Support Devices in the New Heart Allocation System—A United States Nationwide Analysis

This retrospective analysis of the United Network for Organ Sharing (UNOS) database, covering the years 2019 to 2024 with a sample size of 5,325 patients, characterized the evolving landscape of temporary mechanical circulatory support (MCS) under the new heart allocation system. The authors demonstrated a decisive shift toward temporary MCS. By 2024, the utilization of Impella devices at the time of transplantation had increased to 35.3 percent from 4.2 percent in 2019, while the usage of durable ventricular assist devices (VADs) declined significantly (19.8 percent vs 42.4 percent). Despite this aggressive pivot to temporary support, both unadjusted and adjusted 90-day post-transplant survival rates remained similar between the eras (95 percent vs 94.8 percent, p=0.92), and this pattern held across all device types. The authors conclude that the 2018 allocation changes have successfully consolidated a temporary device-driven bridging paradigm, principally led by Impella, that allows high-acuity candidates to reach transplantation safely without compromising short-term survival.