Nov. 5 (HealthDay News) -- In the largest study of its kind to date, Harvard researchers report that they have found drug-eluting stents pose no more risk of heart attack or death than bare metal stents do.

"There has been a long debate about the safety of drug-eluting stents," said lead investigator Dr. Laura Mauri, an assistant professor of medicine at Harvard Medical School and Brigham & Women's Hospital, in Boston. "It was very reassuring to see that there was not an increased rate of death or heart attack."

Mauri presented the findings during a news conference Sunday at the American Heart Association annual meeting in Orlando, Fla.

People who have blocked heart arteries often undergo a procedure called angioplasty, or percutaneous coronary intervention (PCI). A small tube called a catheter is inserted into the blood vessel, then a balloon on the tip of the catheter is inflated to open the blockage and restore blood flow. Typically, a stent, or tiny wire scaffold, is also inserted to keep the vessel open. However, stents carry the risk of blood clots forming within them -- a potentially dangerous condition called stent thrombosis.

It's clear that drug-eluting stents reduce the probability that a patient will need to undergo a repeat procedure within a year. However, there has been heightened concern in the medical community in the past year that coated stents seem to raise the risk of thrombosis.

"Drug-eluting stets reduced the need for revascularization procedures," Mauri said. "What's not clear is what are the long-term consequences of placing a drug-eluting stent versus a bare metal stent in a general population."

This trial took advantage of a statewide registry of people undergoing PCI procedures in Massachusetts.

"In Massachusetts, all patients who undergo stenting procedures, but also bypass procedures, are reported to the state, and their clinical outcomes are monitored," she explained.

Between April 2003 and December 2004, researchers identified 20,654 patients who were listed in the registry.

Participants were enrolled in the trial over an 18-month period, scheduled to coincide with the introduction of drug-eluting stents to the market. All were followed for a minimum of two years after receiving a stent.

Overall, 35 percent of the patients received a bare metal stent and 65 percent received a drug-eluting stent. The study was not randomized, which meant that patients received one or the other based on clinical decisions made by their doctors.

There was no significant difference in the incidence of death or heart attack between the two groups. "If anything, there was a lower rate of mortality in the drug-eluting group as compared to the bare metal stents," Mauri reported.

Dr. Sidney Smith is past president of the American Heart Association and professor of medicine and director of the Center for Cardiovascular Science and Medicine at the University of North Carolina School of Medicine in Chapel Hill. He said the new "findings are similar to what came out in [a recent] Lancet meta-analysis.

"We're still trying to evaluated the data and we're applying more precise criteria," he added.

SOURCES: Sidney Smith, M.D, past president of the American Heart Association and professor of medicine and director of the Center for Cardiovascular Science and Medicine at the University of North Carolina School of Medicine, Chapel Hill; Nov. 4, 2007, news conference with Laura Mauri, M.D., assistant professor, medicine, Harvard Medical School and Brigham and Women's Hospital, Boston; American Heart Association annual meeting, Orlando, Fla.