A new study in the American Heart Association Journal Circulation: Heart Failure raises the question of whether criteria for accepting heart donations are so strict they are keeping working organs from people who could use them.

The concern is that hearts that come from donors with high levels of troponin, a protein involved in muscle contraction that could indicate cell injury, are not accepted as worthy for transplant. But the study authors pointed out there isn’t much data to support such a practice. With only one in three hearts offered for donation accepted for transplantation, a change in donation procedures could increase the amount of available hearts to patients who need them.

In fact, the authors of the study found that there was no association between higher donor troponin levels and recipient death within the first year after transplant. And they found recipients with low, medium and high troponin levels in their hearts’ donors didn’t fare any differently from each other at up to five years after transplant. The type of transplant analyzed, hearts with preserved donor left ventricular ejection fraction, make up more than half of all transplants performed.

The study authors looked at all heart transplants in the U.S. performed on people 18 or older between 2007 and 2014 that fell within certain health parameters—a total of about 11,000 transplants.

Given this new information, the study authors pointed out that the heart donor pool could be expanded  from the current 2,000 to 2,400 hearts a year to allow transplants with hearts from donors with higher troponin levels than are currently accepted. Such a change could save lives of those waiting for heart transplants.