Waiting for a donor’s heart can take a long time, and sometimes after transplantation, the recipient’s body rejects the new heart. A new study may have found a better way to choose a heart donor.
Current protocols for heart transplantation advise on finding a donor with a similar body weight as the recipient. But by doing this, a recipient can end up with a heart that is smaller than what he had.
This study showed that more deaths occurred when a large heart was replaced with a smaller heart, but the survival rate was not affected when the body weight between donor and recipient was different.
The researchers suggested that matching heart size may lead to a better clinical outcome than matching body weight.
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This study examined whether gender, body weight or heart size matching were important when choosing a donor’s heart for transplantation. It was conducted by Robert Reed, MD, from the University of Maryland, and colleagues.
The researchers analyzed data from 31,636 adults who had a heart transplant between 1989 and 2011. Data was provided by the United Network of Organ Sharing. Most of the participants who underwent heart transplantation were male (77 percent) and the median age was 55 years old.
In this study, the researchers reported that the death rate one year after heart transplantation was 12 percent, and this rate increased to 23 percent after five years.
These researchers found that 70.9 percent of the participants received a heart from a donor of the same sex, and 29.1 percent received a heart from a donor of the opposite sex. Furthermore, they found that male participants who received a heart from a woman were 32 percent more likely to die than those who received a heart from a man. However, the survival rate was similar between women who received male hearts and those who received female hearts.
Most of the cases with a mistmach in gender also presented a heart size mistmatch. “Even if the weights of donor and recipient are similar, the female heart is considerably smaller, while women are more often given men’s hearts that are larger," Dr. Reed said in a statement.
Dr. Reed and team also wanted to know the importance of similarity between the body weight of the recipient and the donor. These researchers did not find differences in survival rates between participants who received a heart from a donor with similar body weight and those who received a heart from a donor with different body weight.
These researchers also calculated the total heart mass for each of the participants and assessed whether survival rates were affected by getting either a smaller or bigger heart than their own. They found that patients who received a heart smaller than their own had worse survival rates than those who received a heart with similar size. A donor’s heart that was 10 percent smaller than the recipient’s heart had high probability for complications.
The researchers found that when the donor heart was smaller than the recipient's heart, the risk for rejection was higher. Often, this happened to men who received a heart from a woman. Rejection risk was lower when the donor heart was bigger than the recipient's heart.
Keshava Rajagopal, MD, PhD, another author of this study, reported, “Undersizing a donor heart is very dangerous. It’s like putting a motorcycle engine into a truck.”
This study concluded that when finding a heart donor, it is more important to look for one with a similar heart size than to look at the body weight of the donor.
According to Albert Reece, MD, PhD, MBA, vice president for medical affairs at the University of Maryland and Dean of the School of Medicine, “Heart transplantation has made great strides in recent years; now, thanks to this research, clinicians have a new calculus that promises better donor-recipient matching and better-functioning hearts.”
This study was published on January 8 in The Journal of American College of Cardiology: Heart Failure. The authors had no disclosures to make.