For the past couple of decades, many U.S. transplant centers have used a biomarker called troponin as one way to determine whether a donor heart is suitable for implantation. In an organ that is considered otherwise usable, an elevated level of troponin — a protein found in the bloodstream — is considered a reliable indicator of heart muscle damage. Many transplant centers would reject such a heart.
The problem is that the test’s reliability is based on small studies that showed mixed results, as well as anecdotal information. Using this test may have led to discarding donor hearts that would have functioned well, even as the waiting list for a heart grows.
More than 4,100 people need a heart transplant, according to the United Network for Organ Sharing, the nonprofit organization that runs the U.S. organ procurement and transplantation network, but only one in three donor hearts is judged acceptable.
Now the first large-scale study of troponin as a biomarker for donor hearts has found that there is no difference in patient survival or typical post-transplant complications when donors have elevated levels of the biomarker. Widespread use of those hearts would provide a small increase in the availability of the organs, perhaps 70 or 80 each year, according to the physician who led the study. Last year, 2,804 heart transplants were performed in the United States.
“There is no significant association between elevated donor troponin I level, a biomarker of cardiac injury, and recipient survival for up to five years post-transplant,” the researchers wrote in a study released Tuesday in the journal Circulation: Heart Failure. The team was led by Snehal Patel, an assistant professor of medicine at Montefiore Medical Center, part of the Albert Einstein College of Medicine in the Bronx.
The researchers looked at 10,943 recipients of hearts whose donors had high levels of troponin in their blood between 2007 and 2014. In addition to survival rates, the researchers considered rates of primary graft failure — a severe dysfunction of the transplanted heart — and cardiac allograft vasculopathy — an aggressive form of coronary artery disease — that are both complications after transplants. Researchers found no association between high levels of the biomarker and those conditions.
In an editorial that accompanies the study, two Stanford University School of Medicine doctors expressed hope that the research “will represent a concrete step toward safely expanding donor heart utilization.”
Patel said his transplant center has adopted a new standard for use of hearts with higher levels of troponin, resulting in acceptance of a few more donor hearts that otherwise would have been turned down. He said he hopes others will look at the study and consider the move.
Transplant centers “are scared to push the boundaries,” he said. “They need data.”