麻豆传媒

The limited practice of transplanting hearts from non-heart beating donors has been associated with favorable outcomes and may be gaining traction, United Network for Organ Sharing (UNOS) registry data showed.

Across U.S. heart transplants performed from January 2020 to February 2021 with outcomes data available, there were 127 hearts used from donation after circulatory death (DCD) -- normally considered off-limits for adult heart transplantation (HT) -- and 2,961 from traditional donation after brain death (DBD).

Overall 30-day and 6-month survival rates for transplant recipients were 96.8% and 92.5%, respectively, and were similar between the two donor groups. DCD and DBD transplants were also associated with similar rates of primary graft failure up to 30 days and in-hospital adverse outcomes such as stroke and pacemaker insertion, according to a group led by advanced heart failure cardiologist Shivank Madan, MD, MHA, of Montefiore Medical Center and Albert Einstein College of Medicine in New York City.

Clinical outcomes remained no different between groups in a propensity-matched analysis of 126 DCD and 252 DBD heart transplants, the study authors reported in the .

These findings bolster other early DCD heart transplant studies from Europe and Australia.

DCD donors are those who do not meet brain death criteria and are only considered donor candidates upon irreversible cardiopulmonary arrest after withdrawal of life support. The inherent "warm ischemic injury" on DCD hearts -- considered the start of myocardial ischemia -- has been a major obstacle to transplantation, as well as the inability for operators to functionally assess the asystolic DCD heart.

"However, persistent shortage of DBD organ donors for HT, together with substantial morbidity and mortality in patients on the HT waitlist and improvements in NRP [normothermic regional perfusion] protocols and ex vivo perfusion system technologies for donor organs ... have led to a renewed interest in DCD-HT again," Madan's group noted.

The study authors reported the number of adult DCD donor referrals climbing from 871 in 2010 to 3,045 in 2020. If a donor transthoracic echocardiogram were to be performed for all potential DCD donors, the U.S. would gain approximately 300 additional adult HTs per year, the team estimated.

"It is also important to mention that the current study included a period when large parts of the United States were affected by the COVID-19 pandemic; resulting in severe restrictions and challenges for organ procurement organizations and HT programs. Thus, one could expect the volume of adult DCD-HT to be substantially higher in the coming years, especially with the ongoing trajectory of increasing DCD donors," the researchers said.

"The work by Madan et al is an important summary of an early U.S. experience using DCD donors for heart transplantation and provides further data to support this approach as a crucial strategy to expand the donor heart pool," said cardiac surgeon Francis Pagani, MD, PhD, of the University of Michigan in Ann Arbor, writing in an .

"Although the benefits of DCD heart donation clearly justify its widespread clinical adoption, the logistics of implementing [HT] using the DCD donor pool presents important challenges," he warned. "The use of DCD donors currently requires a significant increase in resources that will appreciably increase the cost and resource utilization associated with [HT]."

There is also the question of ethics: the American College of Physicians recently raised concerns about organ retrieval following cardiopulmonary arrest and induction of brain death in DCD donors, recommending a pause on the practice.

A workaround technique, direct procurement and ex vivo perfusion, may put transplant recipients at a clinical disadvantage, Pagani suggested.

TransMedics recently reported randomized data from a small study suggesting for DCD donor hearts assessed and preserved on the company's OCS Heart System (device not currently approved for use with DCD hearts).

For their study, Madan and colleagues probed the UNOS registry and identified 3,611 adult DCD donors referred during the study period, of whom 136 were deemed of acceptable quality and used for HT.

Compared with rejected DCD donors, those selected for HT tended to be younger, more likely male, and have O-type blood. A history of smoking was less likely for this group, which had no reduced use of heavy alcohol, cocaine, or IV drugs.

Typical recipients of DCD hearts were people with lower priority for transplant and those with type O blood.

Chief among the report's limitations are the small sample and short follow-up, the researchers noted. The UNOS dataset was also subject to errors and lacked important details about the donor heart retrieval process such as resuscitative interventions undertaken and functional assessment of a donor heart after circulatory arrest.

Ultimately, despite the propensity matching of DCD and DBD donors in this study, confounding likely persisted, Pagani cautioned.

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