The 221 groups in the Consumer Reports ratings, fewer than a quarter of those performing bypass surgery in the United States, are the only ones who permitted their information to be published. Only five were rated below average. A report explains the ratings. For example, at one below-average hospital, patients had only a 24 percent chance of receiving the recommended drugs when they left the hospital; at an above-average hospital, they had a 92 percent chance of being given the right drugs.

Dr. Edwards, whose group got two stars, said the Society of Thoracic Surgeons decided it was time to go public with the data the group had been gathering because there had been increasing pressure for this kind of information from lawmakers, Medicare officials and consumer groups. He said the surgeons figured public disclosure would be inevitable, and they wanted to provide meaningful data. He said he thought more and more heart surgery groups would start allowing their data to be published.

Dr. Edwards said there was debate about whether giving patients access to this kind of information could improve overall outcomes from heart surgery, adding, “It’s one of the things we plan to investigate.”

The surgeons’ society collaborated with Consumer Reports, he said, “because the readership of Consumer Reports is certainly a lot broader than any audience we could reach, and we thought there was real value in having a highly reputable independent organization report the results.”

Dr. Edwards added, “As you might imagine, it was not an entirely easy sell to the profession.”

The society had extensive information about patients’ health before surgery and also about the nature of each operation, like how many vessels were bypassed and whether arteries or veins were used to create the bypasses. Dr. Edwards said that kind of detailed information was much more useful than the records that were more commonly available, which generally disclosed only the diagnosis, the procedure performed and whether the patient lived.