New England Journal of Medicine study highlights potential for widening the heart donor pool
A study published in the New England Journal of Medicine confirms that circulatory death donor hearts that are reanimated and perfused with blood outside of the body are as safe and effective to transplant as brain death donor hearts preserved using traditional cold storage. These findings suggest that using hearts donated after circulatory death (DCD) may have the potential to widen the donor pool, helping more patients in need of life-saving heart transplants.
“The greatest challenge in heart transplantation is the limited supply of donor hearts available for patients who are on the waiting list,” said study author Benjamin S. Bryner, MD, assistant professor of Surgery in the Division of Cardiac Surgery and associate director of heart transplantation and mechanical support and director of the expanded donation program at Northwestern Medicine Bluhm Cardiovascular Institute. “Currently, only a few centers around the country perform DCD heart transplants, but we’re hopeful that the results of this trial will encourage more hospitals to invest in the necessary talent, technology and training to make this approach more widely available.”
Most heart transplants are from organ donors who have been declared brain dead following a catastrophic event, such as a traumatic injury or drug overdose, but their heart remained beating, usually with mechanical assistance. With DCD, the donor experienced similar events with no chance of recovery, but they do not meet the criteria for brain death. Instead, death is declared when their heart and respiratory system shut down, either naturally or because life-sustaining care is discontinued.
“We’re very encouraged by the results of this study and the implications it may have for increasing organ utilization and getting more patients transplanted,” said study author Duc Thinh Pham, MD, associate professor of Surgery in the Division of Cardiac Surgery and director of heart transplantation and mechanical circulatory support at Northwestern Medicine Bluhm Cardiovascular Institute. “DCD heart transplants are becoming more common thanks to extracorporeal perfusion technology that resuscitates a stopped heart then keeps blood pumping through it until it can be transplanted into a waiting patient. Despite this recent growth, circulatory death donation still only accounts for a quarter of all deceased organ donations in the United States.”
In the study, adult heart transplant candidates were randomized to receive hearts from donors after circulatory death that were reanimated using extracorporeal non-ischemic perfusion or only hearts from donors after brain death preserved using traditional cold storage. With a total of 180 patients transplanted, 166 were included in the study with 80 receiving hearts from a circulatory death donor and 86 receiving hearts from a brain death donor.
At 6 months, patient survival was 95 percent of recipients of circulatory death donor hearts compared to 89 percent of recipients of brain death donor hearts. The study authors found no difference between the groups in average number of heart graft-related serious adverse events at 30 days after transplant. Five-year follow-up is planned to better understand the long-term outcomes for DCD heart transplantation.
What is donation after circulatory death heart transplantation?
In October 2022, Pham and Bryner completed the first successful DCD heart transplant in Illinois. Until recently, hearts from donors who experience circulatory death were not considered for donation. New technology nicknamed “Heart in a Box” is helping transplant surgeons utilize more of the DCD hearts.
When circulatory death is declared, surgeons remove the stopped heart from the donor within minutes then connect it to the TransMedics Organ Care System (OCS) Heart. This portable “Heart in a Box” device reanimates the heart and simulates the environment inside the human body pumping warm, oxygenated blood through the heart while it is transported for transplant.
Before this technology, transplant teams would place the donor heart on ice in a cooler to preserve it during transport. With standard hypothermic preservation, transplant surgeons only have about four hours to get the heart from the donor to the recipient, limiting how far they can go to retrieve an organ.
“We’re no longer constrained by time, which means our team can travel further and we have more options to find the perfect match for our patients,” Pham said.
In addition to the benefit of time, this technology also gives the transplant team greater ability to examine the heart’s condition and assess its functionality. Surgeons can look for signs of injury or damage from coronary artery disease in a way that was not previously possible when the donor died from circulatory death.
“The ability to examine the beating heart during transport, up until it is implanted, we get better insight into its functionality and greater confidence in an organ’s viability for transplant,” said Bryner, who was part of the team at Duke Health that performed the first DCD heart transplant in the United States.
While DCD has become increasingly common in transplantation for other organs, including liver, lung and kidney, this practice remains rare for heart transplants. Only a handful of centers in the United States currently perform DCD heart transplants, but centers in the United Kingdom and Australia have successfully used this method for years with encouraging results, including positive patient outcomes, decreased wait times and fewer patients left waiting for a transplant.
In the United States, more than 6 million people live with heart failure and an estimated 10 percent of them may eventually require a transplant or other advanced therapies. Currently, the number of people who need a transplant far outweighs the number of donor hearts available. In 2022, more than 7,000 patients in the United States waited for a donor heart. However, only 4,100 heart transplants were performed in the same period due to the scarcity of available donor hearts.
With an estimated 70 percent of donor hearts going unused annually, leveraging technology and innovative techniques, like DCD transplants, has the potential to increase the number of hearts available for transplant by up to 30 percent.
“The most important element in any transplant is the gift of the heart from the donor and their family,” Bryner said. “I’m thrilled that this gives us more opportunity for those families to have some meaning come from that great loss by sharing their loved one’s heart with the recipient.”
In the more than 50 years since the first heart transplant, the limited supply of donor hearts compared to the demand for transplants has remained the biggest challenge. As the field continues to innovate and seek solutions to the organ shortage, DCD presents a unique opportunity.
“In my 20 years as a transplant surgeon, this is the biggest leap forward our field has taken and the best opportunity we’ve had to expand the number of available hearts,” Pham said. “At Northwestern Medicine, we believe this approach will help us to treat and serve more patients with end-stage heart failure. This is a very exciting opportunity to get more patients transplanted in less time, so they can get back to their lives and families.”
The OCS Heart is the only system used in DCD heart transplantation worldwide and the only FDA-approved technology for extracorporeal perfusion and preservation of donor hearts in the United States.
The New England Journal of Medicine study was funded by Transmedics, Inc.; ClinicalTrials.gov number, NCT03831048.