Impact of Extended Heart Recovery Distance on Transplant Outcome Under the Current Heart Allocation Policy: The United Network for Organ Sharing Database Analysis

S. Caroline. Tavolacci¹, K. Okumura², A. Isath³, J. Shimamura², D. Spielvogel², S. Lansman², S. Ohira^2
1Westchester Medical Center, Icahn School of Medicine at Mount Sinai, Irvington, New York ²Westchester Medical Center, Valhalla, New York ³Center for Advanced Heart Disease, Brigham and Women’s Hospital, Boston, Massachusetts

Purpose: The current heart allocation policy prioritizes donor hearts within a 500-mile radius to high priority candidates. However, the advent of organ preservation technology allows donor hearts to be sourced from extended distances (ED). Limited data exist on outcomes of heart recovery from ED under the current policy.

Methods: From October 18, 2018, to March 31, 2023, 11,704 isolated heart transplants (HTs) utilizing brain death donors (DBD) were identified using the United Network for Organ Sharing database. Recipient and donor characteristics and transplant outcomes were compared between those sourced from standard distances (SD) within 500 miles (N=10,324, 88.2%, median distance 201 [78-340] miles) and ED beyond 500 miles (N=1,380, 11.8%, median distance 709 [588-845] miles). Twenty-two donor and recipient characteristics were selected for propensity score matching using nearest method. Donation after circulatory death HT, re-transplant, and multi-organ transplant were excluded. Continuous variables were reported as median and interquartile range, with the Wilcoxon rank sum test for comparisons. Categorical variables were summarized with numbers and percentages with the chi-square test for comparisons. Kaplan-Meier survival analysis and multivariate Cox models with hazard ratios (HR) and 95% confidence interval (CI) assessed survival outcomes. P-values less than 0.05 were considered significant.

Results: Before matching, recipients in the ED group were older (ED, 58 [48.8-64] vs. SD, 56 [46-63] years], had lower body mass index (BMI) (27.1 [23.8-31) vs. 27.5 [24.1-31.4] kg/m2), and lower rates of durable left ventricular assist device (23% vs. 27%) and veno-arterial extracorporeal membrane oxygenation (3.8% vs. 6.1%) compared to the SD group. Donors in the ED group were older (33 [25-41] vs. 32 [25-40] years] and more likely to be female (37% vs. 28%). There were no differences in 1380 matched cases, except for higher donor BMI in ED group (27.3 [23.8-31.8] vs. 26.7 [23.2-31.2] kg/m2, p=0.03).

Waitlist times were shorter in the ED group (21 [7-85] vs. 31.5 [10.8-171] days, p<.001). Ischemic time was longer in ED group (4.45 [4-5.05] vs. 3.35 [2.83-3.82] hours, p<.001), as was the rate of machine perfusion use (ED, 9.6% vs. SD, 1.5%, p<.001). Postoperative outcomes including dialysis, stroke, acute rejection, and hospital stay length, were comparable. One-year survival (ED, 93.1±0.7% vs. Control, 92.2±0.7%, p=0.34) and freedom from graft figure (92.8±0.7% vs. 91.9±0.7%, p=0.39) were similar in matched group and unmatched cohort. Multivariable Cox hazard models showed that recovery distance was not associated with mortality (HR, 1.1, 95% CI 0.9-1.3, p=0.62).

Conclusion: Despite longer ischemic time, HT utilizing DBD donors from ED was safe with comparable survival to hearts ≤500 miles under the current allocation policy. The ability to safely recover heart from ED is paramount to reduce waitlist time and potentially expand donor pool with advent of organ preservation technology.

Identify the source of the funding for this research project: None