PORTLAND – Heart patients who undergo angioplasty are less likely to require bypass surgery or die if their doctors and hospitals are experienced with the procedure, according to a study by researchers at Maine Medical Center.

The study was published Wednesday in the Journal of the American Medical Association.

The principal author of the study, Dr. Paul D. McGrath, said the old saying “practice makes perfect” can explain the study’s findings.

Researchers found that patients treated by “low-volume” doctors were 45 percent more likely to require bypass surgery during the same hospital stay than patients of “high-volume” doctors.

“The more experience a doctor or a center has, the better the outcomes,” he said.

The study looked at data from Medicare files for 167,208 patients who underwent angioplasty procedures at 1,003 U.S. hospitals in 1997.

Angioplasty is performed to clear an artery blockage that deprives the heart of oxygen. A balloon-tip catheter is threaded into the artery to open it.

A low-volume doctor was defined as one who performed fewer than 30 angioplasty procedures a year. High-volume physicians were defined as those who perform more than 60.

The study also found that patients at hospitals that performed fewer than 80 angioplasties a year were 36 percent more likely to die within a month than patients at hospitals that performed at least 160.

The findings support recommendations by the American College of Cardiology that doctors perform at least 75 angioplasty procedures a year and hospitals at least 400 to maintain proficiency, McGrath wrote in the study.

“Patients should make sure they keep themselves informed of what kind of procedures are being offered to them,” he said. “They should ask their doctors how many of the procedures they do, what the outcomes are and how many are done at the hospitals where the work will be performed.”

Studies with similar findings may have been used by the hospital in its arguments against the opening of a cardiac care unit at Central Maine Medical Center, McGrath said.

McGrath said his research interest in angioplasty is unrelated to the dispute between the hospitals. He also said that the Lewiston hospital would not be considered a small hospital as defined in the study.

Maine Medical Center opposed the facility, but the Lewiston hospital won state approval for the center. Officials at Central Maine Medical say the unit will perform up to 300 surgeries and 400 angioplasties in its third year of operation.