Heart attack patients who get an emergency angioplasty to open a blocked artery should routinely have a stent inserted, too, to keep the blood vessel from clogging up again, a large study in Europe and North and South America concludes.

Previous studies have found that balloon angioplasty is superior to clot-dissling drugs when it comes to treating heart attacks, offering better survival and fewer complications.

Nevertheless, the artery can clog up again after angioplasty, and the new study was undertaken to see if stents or a blood-thinning drug improved the outcome. A stent is a wire-mesh tube used to keep an artery propped open.

The research on 2,082 patients showed angioplasty and stents are more effective than angioplasty alone. Without a stent, pateients were effective than angioplasty alone. Without a stent, patients were twice as likely to have problems and need a second procedure.

"What we've established in this study is that stenting should be the routine therapy to treat patients with heart attacks," said Dr. Gregg stone of the Cadiovascular Research Foundation and Lenox Hill Heart and vascular Institute in New York.

Angioplasties are done on about a million Americans each year, mostly as routine treatment for chest pain, Doctors thread ballon-tipped catheters into a blocked artery and inflate the balloon to open it up. Doctors often leave behind a stent.

Some studies, through, had raised doubts about using stents on heart attack victims.

The new study, reported in Thursday's New England journal of Medicine, was conducted at 76 hospitals in North and South America and Europe. Patients were given one of four treatments: Angioplasty alone; angioplasty and the clot-blocking drug ReoPro; angioplasty and a stent; or angioplasty plus a stent and ReoPro.

The study was partly funded by Guidant, which makes the stent, and Lilly Research Laboratoris, which distributes ReoPro. Most of the authors of the study have received research money or been consultants to the companies. The research found there was no significant difference between the groups in rates of death, stroke or a second heart attack. The difference was in scar tissue filling up the artery again, requiring for a second procedure ranged from 16 per cent for angioplasty alone to 5 per cent for stent and the drug.

Stone said ReoPro helped in the first 30 days but did not seem to make that much difference in outcomes at six months.

Dr. David Faxon, president of the American Heart Association, said stents are already used in about 70 per cent of angioplasties overall and their use of heart attacks is less of a concern now than when the study began in 1997. Drug-coated stents now being tested show primes of making them even more effective, he said. The study is "probably not likely to change practice much, but it does give much better justification for what the proactive is doing," said Faxon, one of the many doctors who participated in the study.

Since only about a quarter of US hospitals can perform angioplasties, Stone said ambulances should be allowed to take heart attack victims to those hospitals just as they take people with major injuries to trauma centers.