The percentage of patients who die in the hospital after heart surgery is declining, according to a report released Thursday by the Pennsylvania Health Care Cost Containment Council (PHC4).

It found that the in-hospital mortality rate for patients undergoing heart bypass surgery fell from 3.23 percent in 1994 to 1.54 percent in 2009. In the last five years, death rates for valve surgeries also have fallen. The riskiest procedure the group analyzed remains combined bypass and valve surgery, where 5.28 percent of patients died in the hospital in 2009.

Volume, which is generally associated with higher quality, also has fallen. The average number of open-heart procedures performed annually by hospitals fell from 499 in 2000 to 314 in 2009.

Several local hospitals had higher-than-expected in-hospital or 30-day mortality in at least one category. They included: Abington Memorial, Aria Health, Chester County, Hahnemann University, Hospital of the University of Pennsylvania (HUP), Jeanes, Lower Bucks, Pennsylvania, Phoenixville, and Thomas Jefferson University.

Chester County and Temple University hospitals had better-than-expected 30-day survival after bypass surgeries.

In letters to the council, Aria, Lower Bucks, Pennsylvania, and HUP questioned the way the council had adjusted for the complexity of their patients.

HUP said 30 percent of its heart surgery patients were transfers from other facilities, most of which had their own heart surgery programs. Many also were given mechanical-assist devices in addition to bypass and valve procedures.

Pennsylvania Hospital said the council needed to take into account its bloodless-surgery program, which caters to the needs of patients whose religions forbid the use of blood transfusions. Those patients are more likely to die, said Daniel Feinberg, chief medical officer. "We would strongly encourage PHC4 in the future to exclude such patients from this analysis until an appropriate risk-adjustment can be made," he wrote. "Otherwise, these bloodless [transfusion-free] cardiac surgery patients will find it increasingly difficult to find highly skilled surgeons who will offer them potentially lifesaving surgical procedures in the future."