Decisions can also be influenced by the size of the transplant center and how that affects metrics on survival outcomes. “Because transplant centers are still mainly judged according to one-year post-transplant survival, smaller centers tend to be more conservative in their acceptance of donor hearts,” says Khush. This is reinforced by the significantly higher donor heart utilization rates in Europe (68% vs. 32%), where similar metrics are not used.
The DHS was a large-scale study designed to provide evidence-based guidelines to inform the decision-making process in ways that could immediately increase the number of lifesaving transplants. “We wanted to generate data addressing conditions that frequently result in non-use of donor hearts,” says Khush. “By providing evidence that these hearts are actually suitable for transplantation, we can increase the donor pool and offer patients waiting for a transplant a new lease on life.”
Identifying the incidence and impact of a common, but disqualifying condition
Left ventricular (LV) dysfunction is among the most common reasons for donor heart nonacceptance. Dysfunction in this context is defined as an LV ejection fraction of <50%. In settings involving donations after neurological death (DND), LV dysfunction frequently occurs secondary to other physiological responses following brain death.
Despite evidence of the often temporary and reversible aspects of LV dysfunction under these circumstances, its recognition frequently resulted in the heart being deemed unsuitable for transplant.
The first paper from the DHS addressed three critical questions related to donor hearts in DND settings:
- What is the incidence of LV dysfunction?
- When it occurs, how often does it demonstrate reversibility within 24 hours?
- In cases where the heart was used for transplantation, what was the effect of LV dysfunction on transplant outcome?
The study included 4,333 potential heart donors with DND status. Diagnosis of LV dysfunction was determined by echocardiogram following declaration of brain death. In the event of a positive diagnosis, a second echocardiogram was performed after 24 hours to determine changes in LV function. LV dysfunction was deemed reversible if the second echocardiogram reported an ejection fraction >50%.
The results showed the following:
- There was a 13% incidence of LV dysfunction.
- Among those diagnosed with LV dysfunction, 58% demonstrated reversibility of the condition after 24 hours.
- Among donor hearts accepted for transplant, the one-year survival rate was similar for recipients receiving a heart demonstrating normal LV function (91.3%), reversible LV dysfunction (90.1%), and nonreversible LV dysfunction (91.3%).
“The findings demonstrated not only the relative frequency of LV dysfunction following brain death, but also that it’s largely reversible,” explains Khush.
Importantly, Khush emphasizes that the similarities in survival rates between recipients suggests that many of these hearts are perfectly acceptable for transplant. “My hope is that this data reassures both clinicians and transplant centers of the safety in using donor hearts with LV dysfunction.”
Capitalizing on data from a groundbreaking study
Despite the significant challenges associated with donor-based studies of this kind, the knowledge gained and potential benefits are priceless. This is the first of many research manuscripts currently in development using the DHS data.
“We’re in the process of determining the feasibility of different predictive models of donor heart suitability and transplant success,” says Khush. “We are trying to gain a more nuanced understanding of why hearts are not used for transplant. Given enough information on the donor and the potential recipient, can we predict the outcomes after a transplant? These are some of the possibilities introduced by the DHS.”
Ultimately, the more immediate impact is simply to decrease wait times for those needing a heart transplant. “Given the national shortage of organs for transplantation, we have a responsibility to improve the process of donor heart selection and maximize their availability in a safe manner.”
Learn more about the Donor Heart Study and Stanford Health Care’s Heart Transplant Program and Advanced Heart Failure Program.