DALLAS - Heart patients who had drug-coated stents inserted to prop open blocked coronary arteries should stay on anti-clotting drugs for at least a year, several doctor groups said in an advisory issued Tuesday.

The advisory recommends that doctors tell their patients to take an anti-clotting drug like Plavix and aspirin for a year to reduce the risk of clotting, which could lead to a heart attack or death. The long-term safety of Plavix in stent patients has not been established.

Drug-coated stents are often chosen over bare metal stents because they slowly release medication that reduces the chance of arteries reclogging, which can mean follow-up surgery. However, the newer stents mean a small but significant increased risk of clotting.

The new advisory cited research showing blood clots in up to 29 percent of patients who stopped anti-clotting drugs early after receiving a drug-coated stent. The doctors also cited a study of 500 patients who received the drug-coated stents after a heart attack in which the death rate over the next 11 months was 7.5 percent for those who stopped taking anti-clotting medication compared to 0.7 percent for those who continued the regimen.

The recent information on drug-coated stents and the recommended drug regimen of up to a year means more dialogue between patients and doctors, said Dr. Cindy Grines, chair of the advisory writing committee.

"I think what's happened with the drug-eluting stents is the patients are scared too much," said Grines of the William Beaumont Hospital in Royal Oak, Mich.

The recent publicity about drug-coated stents is on patients' minds, said Dr. John Warner, medical director of the heart, lung and vascular center at the University of Texas Southwestern Medical Center.

"Patients are very informed about this and most are asking the question before we even begin the conversation with them, which is good," he said.

The new information means that before stent surgery, doctors must discuss with the patient whether there's any reason they might not be able to keep up the drug regimen for at least a year, said Warner. If the cost of the drug - Plavix is $4 a day - or an upcoming surgery would require stopping the drug, he said it might be best to use a bare metal stent.

The new advisory - issued by the American Heart Association, American College of Cardiology, Society for Cardiovascular Angiography and Interventions, American College of Surgeons and the American Dental Association - recommends patients postpone elective surgery for a year.

"Before, we would put a stent in and (then) talk about aspirin and Plavix. Now we talk about it before," said Warner, who was not on the advisory committee.