Are We Turning Away Too Many Pediatric Donor Hearts?

PediatricsOnline 

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More than half of all pediatric donor hearts are declined for use each year, despite the fact that many children die waiting for a heart. But why? And what can be done about it? 

Columbus, OH — September 2018

As many as one in every four infants on the heart transplant list dies awaiting an organ. For older children, the risk is lower, but significant wait-list mortality still exists. In an effort to find more hearts for these patients, clinician-researchers at Nationwide Children’s Hospital have started digging into the numbers and questioning the long-held belief in transplant science that so-called “marginal” organs are truly marginal.

“As cardiologists, we should do everything we can to avoid patients passing away while awaiting a heart transplant,” says Deipanjan Nandi, MD, MS, a pediatric cardiologist in The Heart Center at Nationwide Children’s. “I started thinking about where we could find other hearts for these patients and wondered if there were hearts available that were being turned down, and the answer is yes: there are a lot of hearts that never make it into kids.”

Dr. Nandi, Adam Morrison, MD, an advanced fellow in heart failure and transplantation at Nationwide Children’s, and colleagues analyzed trends from 2005 to 2014 in the use of pediatric marginal donor hearts and published their results in August in Pediatric Transplantation. Historically, marginal donors have been defined as having at least one of the following characteristics: left ventricular ejection fraction (LVEF) less than 50 percent, use of at least two inotropic drugs at the time of death, cerebrovascular cause of death, high-risk status according to the Centers for Disease Control and Prevention, or an eGFR < 30mL/min/1.73m2.

According to the team’s analysis of the United Network for Organ Sharing (UNOS) registry data, 35 percent of all pediatric hearts that became available were considered marginal status, of which about 60 percent went unused. Non-marginal donor hearts were not accepted in all cases, either — about 20 percent were turned down. Together, more than half of the 6,778 donor hearts available to pediatric patients during this time period were declined.

Since most children on the transplant list are quite ill, doctors may be avoiding the risk of giving a potentially poor heart to someone who already has a poor heart. But even for perfect hearts, there are valid reasons for non-use. Significant size match differences between the donor and potential recipient, geographic distance and other factors may make it impossible or inadvisable to accept a healthy heart.

“It may be totally appropriate to turn some of these hearts down,” says Dr. Nandi, senior author on the recent publication. “But despite the fact that we commonly accept certain criteria as defining a marginal donor, we still don’t have great data indicating those characteristics result in poorer post-transplant outcomes. Added to the number of potentially perfect hearts being turned down, and that’s hundreds of extra hearts we could have transplanted just in those 10 years.”

Among the marginal donor hearts, those with LVEF <50 percent and use of inotropes were most likely to go unused. Encouragingly, use of all hearts, including those considered marginal, increased over the study period, and Dr. Nandi hopes that trend will continue.

“We feel strongly based on other studies that LVEF at the time of brain death isn’t a good indicator of heart health,” says Dr. Nandi, who works in the Heart Transplant and Heart Failure Program at Nationwide Children’s. “If you put anyone through the stress or trauma leading up to death, it’s likely to bring LVEF down temporarily. We need better science to know what, if anything, about these potentially marginal characteristics may actually matter for the transplant population.”

Thankfully, this area of research is gaining momentum. In an editorial linked to Dr. Nandi’s recent publication, Pediatric Transplantation editors joined the call for more research to minimize the number of pediatric donor hearts going unused. In addition, UNOS has started a workgroup, of which Dr. Nandi is an invited member, to examine the problem from multiple angles, including behavioral and economic perspectives.

In the meantime, Dr. Nandi and his colleagues at Nationwide Children’s have work underway to study specific reasons for heart refusal as well as whether the sickest patients are more or less likely to receive marginal donor hearts. In addition, they will study outcomes among patients receiving marginal versus non-marginal donor hearts. Their goal is to provide evidence-based guidance for physicians.

“Right now, we’re turning down far too many hearts, but I think we’re at the beginning of a shift in this process,” says Dr. Nandi. “I hope we’ll eventually reach an era where we don’t lose patients on the wait list — where we’re using all organs available to our utmost ability.”

References:
Morrison AK, Gowda C, Tumin D, Phelps CM, Hayes Jr D, Tobias J, Gajarski RJ, Nandi D. “Pediatric marginal donor hearts: Trends in US national use, 2005-2014.Pediatric Transplantation. 2018 Aug; 22(5): e13216.

Kirk R, Dipchand AI. “Waste not, want not: Maximizing use of pediatric marginal donor hearts.Pediatric Transplantation. 2018 Aug; 22(5): e13244.