Harvard-affiliate Massachusetts General Hospital, considered one of the nation’s premier medical centers, has a death rate more than double the state’s average for the most common procedure used to treat heart attacks, a Harvard study reported earlier this month.

The study—commissioned by the Massachusetts Department of Public Health—found the angioplasty death rate for patients admitted with heart attacks or in a state of shock was 12.6 percent at Mass. General in 2007, far above the state average of 5.5 percent.

Angioplasty, a process by which a doctor clears blocked arteries using small inflated balloons, is performed on more than 1 million people in the United States each year, according to the American Heart Association.

Dr. Michael A. Fifer ’74, head of Mass. General’s angioplasty program, said the hospital has known about the data for a year and that the high death rate may result from caring for many critically ill patients.

“We very carefully analyzed the deaths. The findings of the reviews showed there were no quality of care issues,” Fifer said. “Every one of the reviews showed that we are faced with critically ill patients.”

Fifer said he’s concerned similar studies may cause physicians to stop taking the hardest cases, which he added is occurring in his department, where doctors are “not taking on as many high risk cases” to lower mortality statistics.

Medical School Professor Sharon-Lise Normand, who led the study, agreed there was a chance doctors would shift away from treating critically ill patients, but said her study controlled for risk factors that would be affected if some hospitals had a sicker body of patients than others.

The death rate may reflect post-op care, Normand said, which reflects both the work of individual doctors and the entire hospital staff.

“There is this tendency by the physicians and the hospitals to say they did the procedure properly,” she said. “We want people to understand mortality also measures what happens after the procedure.”

Cardiologists examined the study, and hospital and physician outliers—like Mass. General—were then examined by oversight committees of cardiologists, Normand said.

Normand said the state sponsored her research to provide patients with information about local hospitals, so they could make informed decisions about their treatments.

“From a public perspective, it’s important to quantify standard of care,” she said.