Some doctors had tried to get mortality data to help them decide where to refer patients, but the hospital did not have the information to share at the time, even internally. In June, after a yearlong legal battle with The Times, UNC provided data that showed its death rate was especially high among children with the most complex heart conditions — nearly 50 percent.

Dr. Wesley Burks, chief executive of UNC Health Care, said in a statement on Tuesday that the health system had made significant efforts over the years to improve its pediatric heart program, and that it would “make further enhancements because we recognize the importance of caring for very sick children with incredibly complex medical problems.”

The health system did not say when the surgeries would resume.

Last month, state and federal regulators determined the children’s hospital was in compliance with federal rules, but “significantly different than it was during 2016-17,” according to a spokesman for the Centers for Medicare and Medicaid Services. A recent survey by the Joint Commission, which accredits hospitals, also found no current issues with the pediatric heart surgery program.

UNC administrators have denied there were problems affecting patient care during those years, saying only that difficult team dynamics had been resolved by staffing and leadership changes. The chief surgeon from that time has been on leave since earlier this year for “family medical reasons,” according to UNC.

The advisory board did not seem to address conditions at the hospital when doctors voiced concerns several years ago, but noted that “team dynamics and interactions appear to be strong.” Recommendations it made to the hospital’s board of directors included continuing to publicly report mortality data; hiring a second full-time pediatric heart surgeon; and considering a joint venture with another hospital to increase the volume of surgeries.

