STENTS: BETTER NEVER THAN LATE.

Opening a blocked artery with balloons and stents can be life saving in the early hours after a heart attack, but a new study concludes that it often does no good if the heart attack occurred three or more days before.

The findings should change medical practice, researchers say, and could affect as many as 50,000 patients a year in the United States. They say doctors should stop trying to open arteries in people who had heart attacks days or weeks before and who are stable and free of pain.

Currently, the balloon procedures, called angioplasty, is used in many of those patients, along with stents, devices implanted to prop open an artery. When patients receive treatment late, it is often because they did not realize that they had a heart attack and delayed going to the doctor or hospital. In some cases, doctors may not make the correct diagnosis right away.

The new study “should change practice, and I believe it will” said Dr. Judith S. Hochman. Director of the cardiovascular clinical research centre ad New York University medical school, and leader of the study, which included 2,166 patients at 217 hospitals in the United States and other countries.

Dr. Elizabeth G. Nabel, director of the National Heart, Lung, and Blood Institute, which helped pay for the research, said: “ This is an important study. It’s definitive. The evidence from it should be weighed very carefully by the groups that formulate guidelines about when to conduct angioplasty n the setting of a heart attack.”

Dr. Hochman presented the results at a meeting of the Ametican Heart Association in Chicago. The study was also publishe online by The New England Journal of Medicine and will appear in the December 7 issue.

Her report is the latest warning form researchers who suspect that stents are being overused and may even be causing heart attacks and deaths. Manufacturers sell $6 billion in stents a year, and cardiologists charge $ 10,000 to $ 15,000 each to implant them.

Dr. Hochman emphasized that angioplasty was still the best treatment for many heart attack patients who go to the hospital early, within 12 hours of when the attack began. The people who generally do best are those who arrive at the hospital and have angioplasty within 90 minutes of the heart attack.

Opening a clogged artery in the early states of a heart attack “early angioplasty” can restore blood flow and reduce damage to the heart muscle. It can sometimes save the muscle after 12 hours. But then doctors decide case by case whether it is worthwhile. About a third of heart attack patients show up after 12 hours.

After a few days have passed, though, there is little or no chance of preventing heart damage. But many doctors open the artery anyway, thinking it may still have long-term benefits and prolong the patients’ lives. In that situation, the procedure is called late angioplasty. It can be helpful in people who are still suffering fro chest pain or have certain other complications from the heart attack.

But what about people who see a doctor more than a day later and are medically stable and free of chest pain? The new study tried to determine of late angioplasty could help them. The findings may come as a rude surprise to many cardiologists.

The 2,166 patients in the study had all suffered heart attacks 3 to 28 days before, caused by a completely blocked coronary artery. The median time since the heart attack was eight days. They were in stable condition and free of chest pain, and were picked at random to receive either heart medicines only or balloon treatment and stents with heart medicines. Most got plain metal stents, but about 8 percent got drug-coated ones. The researchers tracked their health for an average of three years.

There were no differences between the groups. They had the same rates of heart attack, death and heart failure.

If anything, those who had angioplasty seemed to fare a bit worse than those who did not, but the differences were not statistically significant and might have been because of chance, Dr. Hochman said.