BOSTON – Emergency angioplasties, even delayed by hospital transfer, worked better than standard drugs in a heart attack study likely to help change standards for treating the 1.1 million Americans stricken every year.

Most heart attacks are treated only with clot-busting drugs, which can be given by emergency room doctors.

Most hospitals cannot perform quick artery-clearing angioplasties, which require sophisticated surgical backup in case something goes wrong, and doctors are reluctant to postpone treatment while patients are moved to hospitals that can.

However, the Danish study published in Thursday’s New England Journal of Medicine concludes that a transfer to an angioplasty center cuts the risk of death and major complications by about 40 percent.

“I think the study is very provocative and needs to make us think about transferring patients, but very carefully and very thoughtfully,” said Dr. Alice K. Jacobs, who performs angioplasties at Boston University Medical Center and wrote an accompanying editorial.

Comparing 1,129 patients with major heart attacks, 14 percent either died or suffered another heart attack or disabling stroke when treated with drugs alone during the monthlong study. Only 8 percent did when transferred to another hospital for angioplasty. Nearly all were transferred within two hours.

The question of transfers potentially affects hundreds of thousands of patients. In the United States, heart attacks kill about 460,000 people yearly, according to the National Institutes of Health.

Heart attacks develop when clogged and clotted arteries crimp the stream of blood to heart muscle. During angioplasties, doctors snake skinny tubes tipped by plastic balloons into the blocked arteries and then inflate them, restoring blood flow. Angioplasties are generally preferred to drugs alone for emergency treatment of heart attacks.

In recent years, several studies have begun to suggest that the benefits of angioplasties might outweigh delays for hospital transfer. The Danish study helps settle the question, some doctors said.

Still, it isn’t yet clear how many patients, especially in the United States, can be transferred as quickly as the ones in the Danish study, doctors said. “We are not geared up as a nation to deal with things as Denmark was able to,” said Dr. Howard Levite, a cardiologist at Atlantic City Medical Center in New Jersey.

Also, even in the nationalized Danish health system, the researchers took special precautions that ordinary hospitals might not take. Potential transfers were whisked past emergency rooms straight to a cardiac care team. Four percent of patients were ruled out for the study, because doctors felt they were unable to tolerate the transfer.

“I need to know that the transport system is going to be rapid and effective if the patients are sent. I need to know what’s going to happen to the high-risk patients that were not transported in this study,” said Dr. Sidney Smith, a cardiologist at the University of North Carolina who is a past president of the American Heart Association. He also chairs a national professional committee on angioplasty standards that he said would consider this study.

He and others said that, despite its drawbacks, the study does underscore the value of angioplasty transfers when they can be done quickly, within an hour or so. Some doctors said even longer transfer times may be justified for some patients.

They predicted a slow rise in transfers during coming years as doctors, hospitals and ambulance companies evaluate whether they can be set up for quick transport of such patients. “I think it will start a debate on how to transfer patients,” said Dr. Henning Rud Andersen, a cardiologist at Skejby University Hospital in Aarhus and lead author of the study. “It will take several years, but it will come.”