Heart transplantation using the new strategy of donation after circulatory death (DCD) resulted in similar 6-month survival among recipients as the traditional method of using hearts donated after brain death (DBD) in the first randomized trial comparing the two approaches.
“This randomized trial showing recipient survival with DCD to be similar to DBD should lead to DCD becoming the standard of care alongside DBD,” lead author, Jacob Schroder, MD, surgical director, Heart Transplantation Program, Duke University Medical Center, Durham, North Carolina, told theheart.org | Medscape Cardiology.
“This should enable many more heart transplants to take place and for us to be able to cast the net further and wider for donors,” he said.
The trial was published online in the New England Journal of Medicine on June 7.
Schroder estimated that only around one fifth of the 120 US heart transplant centers currently carry out DCD transplants, but he is hopeful that the publication of this study will encourage more transplant centers to do these DCD procedures.
“The problem is there are many low volume heart transplant centers, which may not be keen to do DCD transplants as they are a bit more complicated and expensive than DBD heart transplants,” he said. “But we need to look at the big picture of how many lives can be saved by increasing the number of heart transplant procedures and the money saved by getting more patients off the waiting list.”
The authors explain that heart transplantation has traditionally been limited to the use of hearts obtained from donors after brain death, which allows in situ assessment of cardiac function and of the suitability for transplantation of the donor allograft before surgical procurement.
But because the need for heart transplants far exceeds the availability of suitable donors, the use of DCD hearts has been investigated and this approach is now being pursued in many countries. In the DCD approach, the heart will have stopped beating in the donor, and perfusion techniques are used to restart the organ.
There are two different approaches to restarting the heart in DCD. The first approach involves the heart being removed from the donor and reanimated, preserved, assessed, and transported with the use of a portable extracorporeal perfusion and preservation system (Organ Care System, TransMedics). The second involves restarting the heart in the donor’s body for evaluation before removal and transportation under the traditional cold storage method used for donations after brain death.
The current trial was designed to compare clinical outcomes in patients who had received a heart from a circulatory death donor using the portable extracorporeal perfusion method for DCD transplantation, with outcomes from the traditional method of heart transplantation using organs donated after brain death.
For the randomized, noninferiority trial, adult candidates for heart transplantation were assigned to receive a heart after the circulatory death of the donor or a heart from a donor after brain death if that heart was available first (circulatory-death group) or to receive only a heart that had been preserved with the use of traditional cold storage after the brain death of the donor (brain-death group).
The primary end point was the risk-adjusted survival at 6 months in the as-treated circulatory-death group as compared with the brain-death group. The primary safety end point was serious adverse events associated with the heart graft at 30 days after transplantation.
A total of 180 patients underwent transplantation, 90 of whom received a heart donated after circulatory death and 90 who received a heart donated after brain death. A total of 166 transplant recipients were included in the as-treated primary analysis (80 who received a heart from a circulatory-death donor and 86 who received a heart from a brain-death donor).
The risk-adjusted 6-month survival in the as-treated population was 94% among recipients of a heart from a circulatory-death donor, as compared with 90% among recipients of a heart from a brain-death donor (P < .001 for noninferiority).
There were no substantial between-group differences in the mean per-patient number of serious adverse events associated with the heart graft at 30 days after transplantation.
Of 101 hearts from circulatory-death donors that were preserved with the use of the perfusion system, 90 were successfully transplanted according to the criteria for lactate trend and overall contractility of the donor heart, which resulted in overall utilization percentage of 89%.
More patients who received a heart from a circulatory-death donor had moderate or severe primary graft dysfunction (22%) than those who received a heart from a brain-death donor (10%). However, graft failure that resulted in retransplantation occurred in two (2.3%) patients who received a heart from a brain-death donor versus zero patients who received a heart from a circulatory-death donor.
The researchers note that the higher incidence of primary graft dysfunction in the circulatory-death group is expected, given the period of warm ischemia that occurs in this approach. But they point out that this did not affect patient or graft survival at 30 days or 1 year.
“Primary graft dysfunction is when the heart doesn’t fully work immediately after transplant and some mechanical support is needed,” Schroder commented to theheart.org | Medscape Cardiology. “This occurred more often in the DCD group, but this mechanical support is only temporary, and generally only needed for a day or two.
“It looks like it might take the heart a little longer to start fully functioning after DCD, but our results show this doesn’t seem to affect recipient survival.”
He added: “We’ve started to become more comfortable with DCD. Sometimes it may take a little longer to get the heart working properly on its own, but the rate of mechanical support is now much lower than when we first started doing these procedures. And cardiac MRI on the recipient patients before discharge have shown that the DCD hearts are not more damaged than those from DBD donors.”
The authors also report that there were six donor hearts in the DCD group for which there were protocol deviations of functional warm ischemic time greater than 30 minutes or continuously rising lactate levels and these hearts did not show primary graft dysfunction.
On this observation, Schroder said: “I think we need to do more work on understanding the ischemic time limits. The current 30 minutes time limit was estimated in animal studies. We need to look more closely at data from actual DCD transplants. While 30 minutes may be too long for a heart from an older donor, the heart from a younger donor may be fine for a longer period of ischemic time as it will be healthier.”
In an editorial accompanying the NEJM publication, Nancy K. Sweitzer, MD, PhD, vice chair of clinical research, department of medicine, and director of clinical research, division of cardiology, Washington University School of Medicine, St. Louis, Missouri, describes the results of the current study as “exciting,” adding that, “They clearly show the feasibility and safety of transplantation of hearts from circulatory-death donors.”
However, Sweitzer points out that the sickest patients in the study — those who were United Network for Organ Sharing (UNOS) status 1 and 2 — were more likely to receive a DBD heart and the more stable patients (UNOS 3-6) were more likely to receive a DCD heart.
“This imbalance undoubtedly contributed to the success of the trial in meeting its noninferiority end point. Whether transplantation of hearts from circulatory-death donors is truly safe in our sickest patients with heart failure is not clear,” she says.
However, she concludes, “Although caution and continuous evaluation of data are warranted, the increased use of hearts from circulatory-death donors appears to be safe in the hands of experienced transplantation teams and will launch an exciting phase of learning and improvement.”
“A safely expanded pool of heart donors has the potential to increase fairness and equity in heart transplantation, allowing more persons with heart failure to have access to this lifesaving therapy,” she adds. “Organ donors and transplantation teams will save increasing numbers of lives with this most precious gift.”
N Engl J Med. Published online June 7, 2023. Abstract, Editorial
The current study was supported by TransMedics. Schroder reports no relevant financial relationships.
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