BACKGROUNDMany hearts offered for pediatric heart transplantation (HT) are not placed. In 2016, we initiated a quality improvement endeavor to increase heart offer acceptance. This study assessed the effect of these interventions at our center. METHODSEvaluation of pre-/post-implementation cohorts (1/1/2008-12/31/2016 vs. 1/1/2017- 7/1/2023) comparing donor heart utilization. Six interventions were iterated over time to increase offer acceptance (“extended criteria”): ABO-incompatible transplant, ex vivo perfusion for distanced donors, 3-dimensional total cardiac volume (TCV) assessment, acceptance of Hepatitis-C or SARS-COV-2 infected donors, and institutional culture change favoring consideration of donors previously considered unacceptable (Public Health Service Risk, long CPR duration, etc.). Outcomes studied included annual HT volume, median waitlist duration, sequence number at acceptance, and post-transplant clinical outcomes. RESULTSFrom 1/2008–7/2023 annual transplant volume increased from 16/year to 25/year pre-/post-implementation. Three hundred-thirteen/389 (80%) listed patients were transplanted. Waitlist duration shortened post-implementation (P=0.01), as did the percentage of accepted heart offers utilizing at least one extended criterion (P<0.001). Institutional culture change and TCV assessment had the largest impact on donor heart utilization (P=0.04 &P<0.001). There was no difference in post-HT intubation or cardiovascular intensive care unit (CVICU) days (P= 0.05-0.9), though post-transplant hospitalization duration (P<0.001) increased. Post-transplant survival was unaffected by use of extended criteria hearts (P=0.3). CONCLUSIONSWe report increased donor heart offer acceptance resulting from a longitudinal, multi-faceted effort to increase organ offer utilization, with institutional culture change and TCV assessments having the greatest impact. Use of extended criteria hearts was not associated with inferior survival.