CHICAGO (Reuters) - Enthusiasm for drug-infused heart stents led doctors to test the limits of their effectiveness, resulting in their widespread use for conditions not approved by U.S. regulators, researchers said on Tuesday.
That enthusiasm began to dampen last fall after research showed a small but serious risk of deadly blood clots long after implantation.
Two studies in this week’s Journal of the American Medical Association reveal just how far doctors went with drug-eluting stents. The studies found about half of drug-eluting stents used in 2004 and 2005 were implanted for an unapproved condition.
But the studies differ on the risks associated with using the devices in sicker patients, with one finding the devices are relatively safe even with “off-label” or untested use.
A second study, however, found more-frequent heart complications and urged caution.
Stents are tiny wire mesh tubes used to prop open diseased heart arteries. The drug-eluting kind release a medicine to help keep the artery open.
Johnson & Johnson’s Cypher stent and Boston Scientific Corp’s Taxus stent are the only drug-eluting stents approved for sale in the United States, but competitors are expected to enter the U.S. market next year.
When they were first approved for U.S. sale three years ago, the drug-infused devices were heralded as a revolution because they dramatically reduced the chances of an artery closing again.
The newer devices quickly supplanted older bare-metal versions, generating almost 90 percent of all stent sales by early 2006 and creating a $6 billion market.
But safety fears have led some doctors to switch back to bare-metal stents. Drug-eluting stents now make up about 70 percent of all stent procedures.
Once the FDA approves a treatment, doctors are free to prescribe it as they see fit.
In one study of 5,541 patients, Dr. Nirat Beohar of Northwestern Memorial Hospital in Chicago and colleagues found the risk of death, heart attack or blood clots more than doubled 30 days after drug-eluting stents were used in patients with conditions such as acute heart attack.
But the overall complication rate was relatively low at 2.5 percent, despite their use in high-risk patients.
“I look at this study as being very reassuring,” said Dr. Charles Davidson, one of the study’s authors, in a telephone interview. “Once you adjust for the more complex patient, there really is no safety issue.”
Davidson said he went into the study not knowing how the drug-eluting stents might fare when used in indications that hadn’t been well studied.
“We’re actually doing very well. Safety is comparable,” he said.
He said drug-eluting stents are slightly less effective at keeping arteries clear in these sicker patients, but they are still much better than bare-metal stents because there are far fewer instances of restenosis, or artery reclogging.
In a second study of 3,323 patients treated with drug-eluting stents in 2004 and 2005, 54.7 percent of the patients were treated off label.
“Clinicians should be cautious about extrapolating the benefits of drug-eluting stents over bare metal stents,” the researchers said.
Dr. Magnus Ohman of Duke University Medical Center said the debate over drug-eluting stents is part of the normal process of doctors finding the best way to use new treatments.
“Every new technology ever introduced has always had a little snag,” said Ohman, who wrote an editorial accompanying the studies.
In the editorial he said drug-eluting stents represent a major advance, but doctors need be aware of the risks when using them in unproven, higher-risk patients.
“We shouldn’t throw out the baby with the bath water,” he said.