Chicago ? Is it safe to have your arteries unclogged at a hospital that lacks heart surgeons who can operate if something goes wrong?

Many states ban this except in emergencies like heart attacks. But more small hospitals are trying it in non-urgent cases, and the largest study ever done of this, released on Saturday, suggests it may not be as risky as has been feared.

If confirmed by other ongoing studies, it could change policies in many states. That would mean money for community hospitals struggling to stay profitable and options for patients who must travel to big cities for care.

“What we don’t want is a huge proliferation of hospitals” doing this without strict quality safeguards, or in places that already have many heart centers, said Dr. Ralph Brindis, a heart specialist at the California-based Kaiser Permanente health plan.

He heads a 300,000-patient national database maintained by the American College of Cardiology used in the study. Results were reported at a joint meeting of several cardiology groups in Chicago.

Blocked arteries deprive the heart of blood and can lead to a heart attack. A popular treatment is angioplasty. Doctors push a tiny balloon into an artery, inflate it to flatten the clog, and often place a stent to prop the vessel open.

Medical guidelines allow most hospitals to do these for heart attacks. However, most angioplasties are for chest pain and non-urgent situations, and the rules say hospitals should not offer these unless they have doctors who can do bypass surgery if problems arise.

Small hospitals, which can earn $15,000 or more on each angioplasty, have pressed for a new look at the guidelines. They say stents that came on the market in recent years have made angioplasty safer, by limiting how many times the balloon is inflated and the risk of puncturing an artery.

The patient registry is not definitive science, but suggests that at small hospitals doing this now, with strict quality controls, safety is pretty good.

Researchers compared results from January 2004 through March 2006 on 9,029 patients who had angioplasty at 61 centers without on-site cardiac surgery to 299,132 patients at 404 centers with heart surgeons. Only about half of the hospitals without surgical backup did more than three dozen angioplasties a year.

Yet complications and success rates were similar, said study leader Dr. Michael Kutcher of Wake Forest University in Winston-Salem, N.C.

Roughly four of every 1,000 patients needed emergency bypass surgery – far less than in the past. Nearly 2 percent died at hospitals without backup surgery versus just over 1 percent at larger hospitals, but there was no significant difference once researchers factored in age, severity of illness and other differences among patients.

Results did not differ for urgent or non-urgent angioplasties, though a greater portion of those at small hospitals were emergencies.

The findings should lead to a new look at the guidelines, Brindis said.

“We know from European centers that it can be done safely and effectively. Over half of all angioplasties in Europe and in many countries are done without on-site surgical backup,” he said.

“It could have a huge impact in this country,” said Dr. W. Douglas Weaver, a Detroit heart specialist and president-elect of the American College of Cardiology.