Reviewing the existing professional guidelines and medical literature, Geisinger’s cardiac surgeons came up with their list of 40 action items viewed as best practices — including giving a patient antibiotics within a specified time before surgery, and then giving beta blocker drugs afterward to reduce the chances of an irregular heartbeat.

The doctors nevertheless needed some persuading that ProvenCare would not be some form of inferior cookbook medicine, said Dr. Charles H. Benoit, a cardiac surgeon. “It’s not that we were a uniquely compliant group of personalities,” he said.

Doctors can choose not to follow a particular measure, based on the needs of an individual patient. But they rarely do so. And they also know that any of the steps can be altered if new medical evidence emerges.

When the system began, Geisinger was performing all 40 steps for bypass surgery only 59 percent of the time. Now, an operation is canceled if any of the pre-operative measures have been forgotten. For the last seven months, Geisinger says, its teams have managed to have a perfect record in following all recommended steps for surgery and follow-up care.

“It really has made a change in the way we think about things,” Dr. Benoit said.

The challenge now is to develop the same exacting standards for other kinds of care, like hip replacements, where there is much less medical agreement about what constitutes best practice, Dr. Glenn D. Steele Jr., Geisinger’s chief executive, said in an interview at the system’s headquarters in Danville, Pa.

“I think it’s doable,” he said. “I don’t think it’s going to be easy.”

Even more important, Geisinger must now see if its ProvenCare program has what Dr. Steele refers to as “market legs” — whether it is appealing enough that insurers and employers will be willing to buy it. Heart surgery and follow-up care, which runs about $30,000, are among the biggest-ticket medical offerings that Geisinger provides. But Geisinger executives say outside insurers and employers have indicated that Geisinger would need to include from 5 to 10 other procedures under its plan before they would have enough of their employees affected to make it worth their while to sign up.

Under the experiment, the hospital charges a flat fee for the surgery, plus half the amount it has calculated as the historical cost of related care for the next 90 days. So instead of billing for any additional hospital stays — which typically run $12,000 to $15,000 — Geisinger absorbs that extra cost.