BACKGROUND: Most donor hearts offered for heart transplant (HT) in the United States (US) are turned down. We aimed to understand the reasons for this - focusing on those related to the potential recipient and HT center (i.e. donor-unrelated reasons for refusal). METHODS: The Donor Heart Study (DHS) enrolled 4,333 adult potential heart donors in US from 2015 - 2020. Separately by donor, each HT center who refused an offer for that donor was surveyed on their reason(s) for refusal. We measured the prevalences of 18 distinct donor-unrelated reasons for refusal and their association with the timing of offers (weekend vs. weekday). RESULTS: Our analytic sample included 14,132 unique surveys, each representing a declined offer for one of 3083 donors (mean per donor: 2.56
range: 1 - 17). Donor-unrelated reasons were cited in 24.3% (n = 3441) of surveys
among these, recipient issues (i.e. "recipient ill) were most common (cited in 7%) while resource-related issues (e.g. "logistics", "surgeon unavailable") were rare (<
1%). Neither showed a significant time trend
however, other reasons ("already considering another offer", "distance too far") did so, with an abrupt uptick after 2018. We found that several donor-related (but no donor-unrelated) reasons for refusal (e.g. left ventricular hypertrophy, social risk behaviors) were significantly more common on weekends. Their "weekend-predominance" was not explained by differences in objective donor characteristics. CONCLUSIONS: Nearly one quarter of donor heart offer refusals are due to donor-unrelated reasons. Weekend-predominant reasons for offer refusal signal the highly subjective nature of donor assessment and warrant further scrutiny.