However, nearly all of the procedures performed on cardiac patients experiencing acute symptoms such as a heart attacks appeared to have been medically appropriate, the study found.
Of the elective angioplasties, only about half were graded as clearly appropriate when scored against standardized "appropriate use" criteria.
The use of stents has been under scrutiny in Maryland after a doctor was accused of performing unnecessary procedures.
Dr. Gregory J. Dehmer, a professor of medicine at Texas A&M University and study co-author, said, "If you're talking to your doctor and he says, 'I think we need to put a couple of stents in one of your arteries,' and you are not on medications … you're not having a lot of symptoms, you've never had a bypass … the question you have to ask is, 'Why?'"
"If your doctor can't tell you a reason that is acceptable, maybe you ought to get a second opinion," Dehmer said.
But the study's authors said the findings should be reassuring for patients with acute cardiac symptoms.
"If you're having bad chest pain and you go to the emergency room and the doctor treating you says you're having a heart attack and we need to do a revascularization procedure, you can rest assured, based on these data, that they're giving you good advice," Dehmer said.
The study, published this week in the Journal of the American Medical Association, was led by Dr. Paul S. Chan of Saint Luke's Mid-America Health and Vascular Institute in Kansas City, Mo., and comes in the wake of controversy surrounding alleged overuse of cardiac stents.
The procedures, also called "percutaneous coronary interventions," or PCI, involve slipping a slender metal tube called a stent into a coronary artery narrowed by heart disease. The procedure has been shown to be effective in improving blood flow to the heart and reducing cardiac symptoms. But it also carries risks, such as blood clots and the side effects of using blood thinners to prevent them.
Maryland has been investigating hospitals that might be performing unnecessary stent procedures after a Towson cardiologist was accused of overusing the devices.
Dr. Mark G. Midei ran the cardiac catheterization lab at St. Joseph Medical Center until 2009, when the hospital suspended his operating privileges in the wake of the allegations. The hospital reviewed 2,000 cases and informed 585 of Midei's patients that their stents might have been unwarranted,
The number of stent procedures at St. Joseph fell after Midei lost his privileges there. The number of procedures went from 350 in 2008 to 134 through May 2009 when Midei left, according to a U.S. Senate Finance Committee report on St. Joseph's stent usage, released in December.
Statewide, the number of PCI procedures on non-heart attack patients fell from 10,844 in fiscal year 2008, to 9,205 in fiscal 2010.
Some patients have filed lawsuits against Midei, who has denied the allegations and is countersuing the hospital, contending that it ruined his professional reputation. Midei has not seen or treated patients at St. Joseph since May 12, 2009, according to the hospital. Officials there declined to comment on his pending lawsuit against the hospital.
Midei has gone before the Maryland Board of Physicians, which has said he falsified documents to support the stent procedures as medically necessary. The board could revoke his license, fine him or take some other action; a spokesman said Wednesday that a ruling is coming soon.
State health officials have told legislators that they have focused their investigation on at least one other Maryland hospital because of the number of stent procedures there. A spokeswoman for the state Department of Health and Mental Hygiene declined to comment Wednesday.
The JAMA article noted that the 1,091 hospitals whose July 2009-September 2010 data were included in the study varied widely in the percentage of nonacute or elective angioplasty cases that were deemed inappropriate.
In a quarter of the hospitals, the percentage of elective cases rated as inappropriate exceeded 16 percent. In another quarter, the percentage of elective cases rated as inappropriate was under 6 percent. The rest fell in between.
Part of the problem behind a number of the procedures found to be inappropriate or of uncertain benefit might lie with the rating system, said Dr. Christopher J. White, president of the Society for Cardiovascular Angiography and Interventions.
The "appropriate use criteria," developed jointly by six medical professional organizations, looked for just five factors in the patient records — stability and severity of symptoms; risk as assessed by a stress test; the patient's medications and degree of artery blockage.
"There's a lot of art in our decision-making as to who should be treated," White said. "It's difficult for a computer program to be able to score that. That's why you're seeing such an "uncertain" category."
Dehmer, the study's co-author, agreed. "When I sit down with an individual patient and try to decide what's the best thing to do for grandma sitting in front of me, it takes a lot more than these five elements to make a decision," he said.
For example, the grading criteria did not include age, gender, level of heart function, diabetes or many other factors doctors must consider.
"I would need more clinical information," Dehmer said. "That was a big reason why some of these are graded as uncertain." The reasons why so many cases fell into that category need more study, he said.
Dr. Mandeep R. Mehra, head of the division of cardiology at the University of Maryland School of Medicine, agreed.
"No study is perfect," he said. "Whether it is an imperfect instrument, imperfect gathering of information, imperfect review of information … there are so many issues that can create this variation in the data. But [the study's authors] have called the question, and it behooves the community to try to tackle that."
He said the study's findings should be comforting for patients in cardiac emergencies. In nonacute situations, where the findings were less reassuring, Mehra said, "I would say patients should always consider seeking second opinions."
In elective stent cases, he said, hospitals need to establish "very clear systems" for judging whether a proposed stent procedure conforms with best medical practices.
"In our center," he said, "if we proceed with a nonacute intervention, it goes through three different people at different levels."
And such in-house reviews might be just a start. Mehra said the University of Maryland Medical Center and Johns Hopkins Hospital are in preliminary discussions about establishing a system in which each hospital would review the other's elective stent cases.
"Why not?" he asked. "There's no reason why we cannot consider ways of ascertaining appropriateness and guiding best practices at the highest pinnacle of academic medicine."