The changing landscape of temporary mechanical circulatory support devices in the new heart allocation system: A US nationwide analysis

Objective The 2018 change in the US heart transplant allocation system was associated with a significant increase in the use of short-term mechanical circulatory support. Using a large national database, we aimed to analyze changes in mechanical circulatory support device use and clinical outcomes after the allocation change. Methods According to the United Network for Organ Sharing database, 5325 adult patients were identified who underwent heart transplantation in 2019 or 2024 (2019: n = 2226; 2024: n = 3099). Mechanical circulatory support type at registration and transplant, patient demographics, and 90-day unadjusted and adjusted survival were compared between the groups. Results Compared with 2019, patients being registered for heart transplantation in 2024 were more likely to have an Impella device (26.4% vs 3.3%, P < .001). At the time of heart transplantation, 2024 patients were less likely to be on a durable ventricular assist device (19.8% vs 42.4%) or an intra-aortic balloon pump (23.5% vs 37.8%), whereas the proportion of patients on extracorporeal membrane oxygenation slightly increased (9.2% vs 6%) and those with the Impella drastically increased (35.3% vs 4.2%, P < .001). Unadjusted and adjusted 90-day survivals were similar in 2019 and 2024 (95% vs 94.8%, P = .92). Unadjusted and adjusted 90-day survivals were similar for patients on extracorporeal membrane oxygenation (92% vs 92%, P = .63), intra-aortic balloon pump (97% vs 96%, P = .63), or the Impella (97% vs 96%, P = .27) in both years. Conclusions Since the adoption of the new allocation system, there has been a dramatic increase in the use of Impella devices. Overall and device-specific survival remain unchanged.