But sicker patients may be getting bare metal devices, study suggests
TUESDAY, June 24 (HealthDay News) -- Heart patients who got drug-coated stents did better than those who received the bare-metal kind of stent, a major study found.
But it isn't a simple either-or issue, the study authors said.
The researchers compared the experience of almost 39,000 Medicare recipients who underwent non-emergency stenting between October 2002 and March 2003, when only bare-metal stents were available, with that of more than 28,000 patients who got stents from September through December 2003. During the later time period 61.5 percent of patients received drug-coated stents.
A stent is a tiny tube placed into an artery or blood vessel to keep the vessel open.
Only one coated stent -- Cordis Corp.'s sirolimus-coated Cypher -- was available in 2003. Over a two-year follow-up period, 22.8 percent of the people in the bare-stent era required a repeat procedure to open a blocked coronary artery. In comparison, just 19 percent of those in the coated-stent era required a second procedure, an 18 percent reduction, the researchers noted.
The overall two-year death rate in both periods was the same, 8.4 percent, but there was a reduction in the number of heart attacks (formally called ST-elevation myocardial infarctions) from 2.4 percent to 2.0 percent.
But, the overall survival of bare-metal stent recipients declined when the coated-stent era began, the study found. "Why should having a coated stent available affect the survival of bare-metal stent patients?" asked lead researcher Dr. David J. Malenka, a cardiologist at Dartmouth Medical School. "The reason is that somehow sicker patients were getting bare-metal stents."
So the study's results were affected by "selection bias," Malenka said. "Patients who got drug-eluting stents somehow were healthier and more likelier to survive," he said. In many cases, it was a matter of anatomy, he added. Patients with complex artery problems got bare-metal stents, while those with simpler anatomy got drug-coated stents.
But the bottom line is that drug-coated stents did decrease the need for new procedures when an artery became blocked again, the study found. Drug-coated stents might increase the incidence of such blockages, "but when you compare the increased risk of late thrombosis [clotting] associated with drug-eluting stents, that risk is more than counterbalanced by reducing the adverse events associated with revascularization [artery-reopening procedures]," Malenka said.
The study was funded in part by the U.S. National Institute on Aging and is published in the June 25 issue of the Journal of the American Medical Association.
While drug-coated stents are now used in perhaps 70 percent of cases, the bare-metal kind has its uses, Malenka said. "We understand that patients who get drug-eluting stents have to be on two antiplatelet [clot-preventing] drugs for at least a year," he said. "Not everyone can be able to afford them or be compliant with their use."
Dr. Kirk Garrett, clinical director of interventional cardiovascular research at Lenox Hill Hospital's Heart and Vascular Institute in New York City, said the new study helps to establish the appropriate use of drug-coated stents.
"We went through a difficult period when it appeared there might be real problems with drug-eluting stents involving clot formation, leading to deaths and heart attacks," Garrett said. "We found that, in fact, there does not seem to be an important signal of risk with drug-eluting stents around the world."
The Dartmouth report is the latest in "half a dozen studies, all of which indicate the use of drug-eluting stents is perfectly safe and does yield an important reduction in the need for further procedures," Garrett said.
The study was done before a second coated stent, Boston Scientific Corp.'s paclitaxel-coated Taxus, was marketed. The U.S. Food and Drug Administration has just approved a third model, Medtronic's Endeavor, coated with zotarolimus, and other products are in the testing pipeline.
The Dartmouth study differed in one respect from a major study done at the University of Pennsylvania, which looked at 72,000 persons who got stents during a nine-month period in 2003. That study also found a reduction in the need for new artery-opening procedures, but it also found a reduction in overall mortality.
You wouldn't necessarily expect a reduction in mortality, because most people don't die of restonosis [reclosing of an artery], Garrett said.
Learn about stents from the U.S. National Library of Medicine.
SOURCES: David J. Malenka, M.D., cardiologist, Dartmouth Medical School, Lebanon N.H.; Kirk Carrett, M.D., clinical director of interventional cardiovascular research, Lenox Hill Hospital Heart and Vascular Institute, New York City; June 25, 2008, Journal of the American Medical Association
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