Piedmont Healthcare’s CEO is ill and on leave, the Atlanta Business Chronicle reported Monday.

Tim Stack, 59, has led the Atlanta-based system for more than a decade, building it through expansion to include the former Henry Medical Center and Mountainside Medical Center in Jasper. It also recently opened the new Piedmont Newnan Hospital. The system’s flagship facility is Piedmont Hospital in Buckhead.

Gregory Hurst, the health system’s second-highest executive, has taken over the CEO responsibilities in the interim, the Business Chronicle reported.

Stack is a major figure in the state’s hospital industry. He has increased the Piedmont system’s revenues dramatically during his tenure, and has been a strong advocate for a reconfiguration of the state’s hospital tax, which is due to expire next year.

The tax, passed by the state Legislature in 2010, brought an increase in payments to Georgia hospitals for services rendered to Medicaid patients. Some hospitals have come out ahead through the new tax, while others suffered a net loss. Piedmont Hospital in Buckhead was a major loser under the formula.

A Piedmont spokeswoman Monday declined to comment on Stack’s health or interim replacement with Georgia Health News.

Piedmont has also pursued cutting-edge payment reforms, which have been ignited under the 2010 health reform law.

That year, health insurer Cigna and Piedmont Physicians Group in Atlanta launched the state’s first accountable care organization (ACO) pilot program. An ACO is a grouping of hospitals and doctors that aims to coordinate medical services for patients.

At a March health care conference in Atlanta, Stack talked about the trend toward revamping the health care payment system so the value of services gets rewarded — not the volume of services delivered.

“It’s all changing,’’ said Stack. “It’s not going back.’’

Stack said Piedmont is working on improving coordination of patient care. Medical care is still fragmented, Stack said. “It truly is not being done in the best way.’’

The goal, he said, is ‘‘to take care of patients the best way we can.’’

“We’re going to compete against everyone,’’ Stack added. “We want to be the best.’’

Piedmont Healthcare also recently announced the creation of its South Region, which includes Piedmont Henry Hospital, Piedmont Fayette Hospital and Piedmont Newnan Hospital. Here’s a Henry Daily Herald article about the reorganization.