Paradoxical outcome of heart transplantation associated with institutional case volume

Center Volume Predicts Improved Early Outcomes in Multiorgan Heart Transplantation

PURPOSE

Center volume is associated with improved survival after isolated heart transplant, but its impact on multiorgan heart transplant (MHT) outcomes is unknown. This study examines the impact of institutional MHT volume on MHT outcomes.

METHODS

Adult patients undergoing first time MHT from 2011 to 2021 were identified in the United Network for Organ Sharing database. Transplant centers were annually classified as low-, medium-, or high-volume if they performed <3, 3 to 5, or ≥6 MHTs that year, respectively. Graft failure was defined as death, failure, or re-transplantation of any allograft.

RESULTS

A total of 1860 MHTs were performed at 104 centers, including 482 (26%) at low-, 601 (32%) at medium-, and 777 (42%) at high-MHT volume centers. Noncardiac allografts included kidney (83%), liver (16%), and lung (2%). The proportion of MHTs performed at high-volume centers increased from 10% in 2011 to 62% in 2021. Recipient age, race, and body mass index did not vary by center volume (all P > .05). Patients at high-volume centers were more likely to be in the intensive care unit pre-transplant (58% vs 44%, P < .001) and have shorter waitlist times (47 vs 92 days, P < .001) than those at low-volume centers. 30-day graft survival was higher in combined medium- and high-volume compared with low-volume centers (95% vs 92%, P = .004). Increasing center MHT volume was protective against 30-day graft failure (adjusted hazard ratio 0.93 [0.88-0.98]) on multivariate Cox regression.

CONCLUSIONS

Higher MHT volume is associated with improved early graft survival after MHT, which may justify centralizing the performance of MHTs to high-volume centers.

Utilization of the percutaneous left ventricular support as bridge to heart transplantation across the United States: In-depth UNOS database analysis

BACKGROUND

Intra-aortic balloon pump (IABP) and Impella device utilization as a bridge to heart transplantation (HTx) have risen exponentially. We aimed to explore the influence of device selection on HTx outcomes, considering regional practice variation.

METHODS

A retrospective longitudinal study was performed on a United Network for Organ Sharing (UNOS) registry dataset. We included adult patients listed for HTx between October 2018 and April 2022 as status 2, as justified by requiring IABP or Impella support. The primary end-point was successful bridging to HTx as status 2.

RESULTS

Of 32,806 HTx during the study period, 4178 met inclusion criteria (Impella n = 650, IABP n = 3528). Waitlist mortality increased from a nadir of 16 (in 2019) to a peak of 36 (in 2022) per thousand status 2 listed patients. Impella annual use increased from 8% in 2019 to 19% in 2021. Compared to IABP, Impella patients demonstrated higher medical acuity and lower success rate of transplantation as status 2 (92.1% vs 88.9%, p < 0.001). The IABP:Impella utilization ratio varied widely between regions, ranging from 1.77 to 21.31, with high Impella use in Southern and Western states. However, this difference was not justified by medical acuity, regional transplant volume, or waitlist time and did not correlate with waitlist mortality.

CONCLUSIONS

The shift in utilizing Impella as opposed to IABP did not improve waitlist outcomes. Our results suggest that clinical practice patterns beyond mere device selection determine successful bridging to HTx. There is a critical need for objective evidence to guide tMCS utilization and a paradigm shift in the UNOS allocation system to achieve equitable HTx practice across the United States.