Despite advances in mechanical circulatory support devices (MCS), heart transplantation remains the treatment of choice for advanced heart failure. Its primary limitation is the restricted number of available organs, leading to an imbalance between transplant candidates and donors. Consequently, efforts to expand the donor pool are continuous. Until recently, this pool included only patients declared brain dead. Now, it also includes those for whom therapeutic efforts are limited due to futility, with an anticipated fatal outcome in the short term, either due to an advanced, irreversible medical condition (extensive brain damage, terminal chronic diseases) or patient preference (aid in dying). This is known as donation after circulatory death (DCD).

The increase in DCD over recent years has been remarkable and is expected to continue. However, its unique aspects compared to brain death donation raise concerns regarding post-transplant outcomes. Consequently, not all waitlisted (WL) patients are considered eligible for DCD organs. To address this, the authors analyze the impact of DCD adoption in the U.S., reviewing the national transplant database from October 2018—when WL prioritization criteria changed—until December 2022.

In this analysis, WL patients were divided into two groups: those eligible only for brain death donation (thus, not DCD candidates) and those eligible for both brain death and circulatory death donations. The authors pursued two objectives:

1. Evaluate the impact of DCD on the WL: They compared one-year transplant incidence, WL removal due to death/clinical deterioration, and one-year survival post-WL inclusion (sum of patients alive on the WL and those transplanted within a year). Parameters were analyzed in subgroups based on blood type, transplant priority, MCS use, and center, dividing centers by DCD eligibility rates (0%, <50%, or >50%).
2. Assess DCD’s impact on post-transplant survival: They compared one-year survival post-transplant between the two groups, with and without propensity score adjustment. Additionally, a sub-analysis within the DCD group assessed the impact of retrieval technique (ultra-rapid vs. normothermic perfusion recovery).

During the study, 14803 WL patients were included, with 2516 candidates for DCD hearts. Compared to the 12287 non-DCD candidates, these 2516 were older, had more comorbidities (diabetes, renal impairment), and less long-term MCS presence. In the unadjusted analysis, there were no differences in one-year cumulative transplant incidence. However, after adjusting for blood type, region, heart failure etiology, etc., DCD candidates were 23% more likely to be transplanted. Additionally, DCD candidates had a lower WL removal rate due to death/clinical deterioration. Finally, listing at a DCD program center increased transplant probability and reduced WL removal risk, with the highest survival rates among centers where >50% of WL patients were DCD candidates.

During this period, 12238 isolated heart transplants were performed: 602 DCD and 11636 from brain death donors. Among DCD recipients, there was a higher proportion of males, blood type O, prior cardiac surgery, and prolonged MCS. The unadjusted one-year survival analysis found no differences (91.3% in non-DCD vs. 92.7% in DCD). Propensity-score-adjusted analysis between two comparable groups of 257 patients showed no survival differences (92.5% in non-DCD vs. 92.8% in DCD), though the DCD group had a higher incidence of postoperative dialysis. Lastly, within the DCD group, no differences were found between extraction methods in terms of postoperative complications or one-year survival.

The authors conclude that DCD increases transplant probability and reduces WL removal due to death/clinical deterioration, all while maintaining good one-year survival outcomes.

COMMENTARY:

DCD continues to grow, with more transplant groups adopting it. In the U.S., the number of DCD heart transplants rose from 103 in 2020 to 301 in 2022, though it remains a minority, accounting for only 4.9% of transplants from 2018 to 2022. Furthermore, only 17% of WL patients were DCD candidates.

Analyzing the UNOS database and adjusting for factors affecting transplant likelihood, the authors found DCD increased transplant probability and reduced WL removal due to death or deterioration, especially in some priority statuses (status 3 and 4). Patients most benefitting were those listed as priority 4, those with long-term MCS, and blood type B. However, these findings might not fully apply elsewhere, given the unique prioritization and geographic factors in the U.S.

Regarding transplant outcomes, although previous reports suggest similar results to brain death donation, most studies had smaller sample sizes. This study found comparable one-year survival between both groups in both unadjusted and propensity-adjusted analyses. However, the DCD group had a higher incidence of postoperative dialysis, which the authors link to right ventricular failure and longer “cross-clamp” times in DCD. These prolonged times only occurred in ultra-rapid retrieval cases using Transmedics OCS®, allowing longer preservation times (mean of 6.1 hours). Within the DCD group, there were no significant differences between retrieval methods.

The main study limitations include its retrospective nature and the use of a general database, which lacked specific variables relevant to this study. This affects the DCD retrieval method comparison, making it somewhat suboptimal. Additionally, many centers simultaneously participated in a Transmedics OCS® trial, a possible confounder. Only short-term (one-year) survival results were reported, leaving open the question of long-term outcomes.

In summary, incorporating DCD into our transplant program will increase our donor pool and reduce wait times. The technique’s complexity, logistical challenges, and even ethical aspects should not deter its adoption given its positive outcomes.

REFERENCE:

Hess NR, Hong Y, Yoon P, Bonatti J, Sultan I, Serna-Gallegos D, et al. Donation after circulatory death improves probability of heart transplantation in waitlisted candidates and results in post-transplant outcomes similar to those achieved with brain-dead donors. J Thorac Cardiovasc Surg. 2024 May;167(5):1845-1860.e12. doi: 10.1016/j.jtcvs.2023.09.012..