Can Donation After Circulatory Death Organs Safely Expand the Donor Pool for Combined Heart-Kidney Transplantation?

Z. Brennan¹, A. Bilgili², q. chen³, M. Adjei⁴, J. Steggerda⁴, J. Jacobs⁵, M. E. Bowdish⁶, D. Megna⁷, J. Chikwe¹, P. Catarino^7
1Cedars-Sinai, Los Angeles, California ²The University of Florida College of Medicine, Jacksonville, Florida ³Cedars Sinai Medical Center, Los Angeles, California ⁴Cedars-Sinai Medical Center, Los Angeles, California ⁵University of Florida, Gainesville, Florida ⁶Cedars Sinai Medical Center, La Canada, California ⁷Department of Cardiac Surgery, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California

Purpose: Donation after circulatory death (DCD) has expanded the donor pool for isolated heart transplants, but experience with combined DCD heart-kidney transplants is more limited. Our objectives were to evaluate trends and compare outcomes of heart-kidney transplants using donation after brain death (DBD) versus DCD organs.

Methods: The United Network for Organ Sharing Database was queried to identify 2361 adult patients receiving combined heart-kidney transplants between 12/1/2014 and 12/31/2023, including 2249 recipients of DBD (95.3%) and 112 recipients of DCD heart-kidney transplants (4.7%). Trends in heart-kidney transplantation volume were evaluated using linear regression. The primary end-point was 1-year post-transplant survival, compared between DCD and DBD recipients with Kaplan-Meier analysis and adjusted using multivariable Cox regression accounting for 26 baseline donor and recipient characteristics. Median follow-up was 176 days (interquartile range 30-369) for DCD and 732 days (interquartile range 262-1514) for DBD. The kidney donor profile index (KDPI) estimates how long a kidney is expected to function relative to all of the kidneys recovered in the U.S. during the last year; lower scores are associated with longer function and better graft quality, and as scores increase, function and quality decrease.

Results: Overall volume of heart-kidney transplants increased (141 in 2015, 208 in 2023, p< 0.001, R2=0.99). At baseline, DCD recipients had similar age, weight, and height compared to DBD recipients but were significantly less likely to require pre-operative mechanical circulatory support (53.5 vs. 79%), an intra-aortic balloon pump (8.0 vs. 21.4%), dialysis (34.0 vs. 46.7%), or intensive care unit admission (35.1 vs. 57.1%) (all p< 0.05). Compared to DBD donors, DCD donors were significantly younger (30 vs. 31.0 years, p=0.04) and had lower baseline creatinine (0.82 vs. 0.90 mg/dL, p< 0.01) and higher KDPI (22.5 vs. 18.0, p=0.03). They also had longer kidney ischemic time (19.9 vs. 15.6 hours, p< 0.01), longer heart ischemic time (3.5 vs. 3.3 hours, p< 0.01), and improved left ventricular ejection fraction (64 vs. 60%, p=0.03, Table 1). One-year recipient survival was 82.1% (95% CI 73.1%-92.2%) after DCD and 88.7 (95% CI 87.3%-90.1%) after DBD heart-kidney transplant (adjusted HR 0.94, CI 0.48-1.89, p=0.89) (Figure 1). Risk factors associated with worse one-year survival included: pre-operative extra-corporeal membrane oxygenation (HR 2.26, CI 1.31-3.90, p< 0.01), bilirubin >2 mg/dL (HR 1.71, CI 1.14-2.56, p< 0.01), and KDPI 21-30% (HR 1.69, CI 1.14-2.50, p< 0.01) compared to a lower index.

Conclusion: In the United States, both DCD and DBD combined heart-kidney transplants increased by approximately 50% between 2014 and 2023. There was no significant difference in adjusted 1-year mortality between DCD and DBD heart-kidney recipients. The use of DCD organs may safely expand the donor pool for combined heart-kidney transplant.

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