WEDNESDAY, Oct. 3, 2007 (HealthDay News) -- Drug-coated stents offered a clear advantage over the bare-metal kind for high-risk patients with blocked coronary arteries, a large Canadian study found.
The rate of restenosis -- having the artery become blocked again after stent implant -- was "significantly lower" over the following two years for those getting drug-coated stents, 7.4 percent versus 10.7 percent. The three-year death rate was 5.5 percent in the coated-stent group, compared to 7.8 percent in the bare-metal group.
"We found the results in low-risk patients were almost identical [between the two types of stents], so we would reserve coated stents for high-risk cases," said study lead author Dr. Jack V. Tu, a senior scientist at the Institute for Clinical Evaluative Sciences in Toronto.
The study findings also provide some comfort about worries that a high rate of restenosis increases the risk of heart attacks in those getting coated stents. The two-year heart attack rate was similar in the two groups, 5.2 percent for bare-metal stents and 5.7 percent for coated stents.
"These were traditional heart attacks rather than being caused by restenosis, so it provides a lot of reassurance," Tu said.
The findings are published in the Oct. 4 issue of the New England Journal of Medicine.
The dominant drug-eluting stent used in the trial was the Taxus, coated with the drug paclitaxel and marketed by Boston Scientific, Tu said. It was used in 80 of those getting a coated stent, with about 17 percent getting the Cypher, which is coated with sirolimus and marketed by Cordis.
Recent studies have found the risk of restenosis is lower with the Cypher stent. Tu said his group has not yet looked for a product-to-product comparison.
The study defined high risk as the presence of two of three risk factors for restenosis -- diabetes, having smaller blood vessels and having very long blockages.
Use of a bare-metal stent versus a drug-coated stent thus depends on a recipient's risk profile, Tu said. "Unless I were a high-risk patient with two or three risk factors, I would be better off with a bare-metal stent," he said. I would reserve the coated stent for high-risk patients.
Dr. Steven Nissen, chairman of cardiovascular medicine at the Cleveland Clinic, said the findings should be interpreted with care, because the study was "observational," looking at what was done in medical practice without the strict effort to balance all factors done in a controlled trial.
"Observational data has significant limitations, particularly that the patients who received bare-metal stents rather than coated stents may have been different," Nissen said. "Observational studies try to account for those differences by matching patients carefully, but matching is an imperfect science."
The "big surprise" of the study was the reduction of the death rate with drug-eluting stents, Nissen said. "But the authors appropriately caution that the finding needs confirmation by randomized clinical trials," he said.
"In my view, we've learned all we can from observational trials," Nissen added. "We need a good long-term controlled trial" of stents.
However, Dr. Kirk Garratt, clinical director of interventional cardiovascular research at Lenox Hill Hospital in New York City, said the Canadian trial was no ordinary observational study.
"The best thing about this paper is the technique they used for matching bare-metal stent patients with drug-coated stent patients," Garratt said. "It was easy for me to figure out quickly and easily the impact of having put a drug-coated stent into a patient. It was linked to an important improvement in how patients do over a long period of time."
One reason the coated stents performed so well is that Canada's health-care system automatically provides the clot-preventing drug Plavix, plus aspirin, for all stent recipients. Those drugs are recommended for American recipients, and the federal government recently began to pay for them, Garratt said.
"That is reason to hope that the U.S. population will see these benefits in the next few years," he said.
You can learn why and how stents are used from the U.S. National Heart, Lung, and Blood Institute.