US Heart Transplant Trials Show Demographic Representation Gaps

Researchers conducted a cross-sectional analysis of US-based heart transplant clinical trials registered on ClinicalTrials.gov between 2000 and 2025 that had publicly available results. They included 27 trials with 2,271 participants and compared reported sex, race and ethnicity distributions with US Census data and heart transplant recipient demographics.

Women accounted for 24.2% of participants (95% CI, 22.5%–26.0%), compared with 27.0%–28.4% of heart transplant recipients in 2010 and 2020. White participants made up 75.3% of trial enrollment, versus 59.3% of recipients in 2020. Black participants accounted for 15.5%, compared with 25.0% of recipients. Hispanic or Latino participants represented 9.7% and Asian participants 1.7%; multiracial participants accounted for 0.3%, while Indigenous and Pacific Islander participants were not represented. Race and ethnicity reporting was universal in trials conducted after 2020.

The findings indicate that trial populations may not reflect the diversity of people receiving heart transplants, potentially limiting how broadly results apply. The analysis is descriptive and does not establish the effects of underrepresentation on outcomes or identify its causes. The authors call for standardized demographic reporting and enrollment strategies focused on equity.