FDA panel to probe clotting, new stents
Study: Drug-coating increases risk fivefoldNov 30, 2006 | Chicago Tribune
With a new report blaming drug-coated heart stents for a fivefold increase in the risk of clotting problems and a Food and Drug Administration panel poised to investigate the devices next week, hospitals that once embraced the new stents are starting to retreat to an older, cheaper version.
Drug-coated stents are implanted in nearly a million Americans a year to keep arteries propped open. They are the next generation of a metal mesh device inserted after angioplasty, a procedure in which doctors use a balloon-tipped catheter to open pathways to the heart.
Arteries treated with the first bare metal stents had a tendency to close in some patients. The drug coating was designed to inhibit the development of scar tissue and stop the vessel from clogging again.
The promise of the new device so impressed the medical community that doctors turned to the drug-coated version for most patients since they came on the market in 2003. Some hospitals used drug-coated stents in more than 90 percent of their patients.
But recent reports of clotting issues are causing doctors to think twice about using the newer models in some patients. A new report released Wednesday, based on research led by The Cleveland Clinic, showed a four- to fivefold increased risk of clots compared with the bare metal variety of stent.
Some hospitals have responded by cutting their use of drug-coated stents by 10 percent or more since reports of potential risks began surfacing last fall about so-called late stent clotting, which develops after the device has been in the patient for several months or longer.
"There is that nagging concern about late stent thrombosis that [clotting] concern is out there," said Dr. Gary Schaer, director of the cardiac catheterization lab at Rush University Medical Center in Chicago.
At Rush, Schaer said the hospital had been placing drug-coated stents in patients about 85 percent of the time, but recently that number has dropped to about 75 percent.
In its most recent two-month period, Rush said 68 percent of patients implanted with stents received the drug-coated version. During the same period last year, 88 percent received the drug-coated variety. The hospital said it places about 600 coronary stents in patients annually.
Those types of numbers are bad news for stent manufacturers, including North Chicago-based Abbott Laboratories, which placed a huge bet on heart stents when it purchased Guidant Corp.'s vascular business earlier this year for more than $4 billion. Abbott currently has a drug-coated stent in development for U.S. patients.
Only two drug-coated stents are on the U.S. market: Boston Scientific Corp.'s Taxus and Johnson & Johnson's Cypher. Both have lost sales. Although Abbott has a drug-coated stent in some European countries, analysts say Johnson & Johnson and Boston Scientific dominate the $6 billion worldwide market.
Drug-coated stents are big business. They can cost $2,200 or more each, compared with $600 to $800 for the uncoated variety, hospitals say.
But the companies and some doctors maintain the risks are small, saying there have not been enough studies completed to warrant a return to bare metal stents. Even hospitals that have curtailed implanting the drug-coated version say they will stick with it for most patients.
At Loyola University Medical Center in west suburban Maywood, where the hospital implants more than 1,500 stents a year, doctors say the risk is not enough to justify a retreat from drug-coated stents.
"There is no evidence that bare metal stents are any safer, they were not as well scrutinized as drug-eluting stents," said Dr. Fred Leya, director of interventional cardiology at Loyola University Health System, parent of the medical center.
While Leya said the risk of clotting in patients is worrisome, he said clotting after the stent has been in the artery for several months or even longer than a year affects "no more than 3 to 4 percent," of patients. A widely reported study last month found a 2.9 percent risk of clotting after three years and the potential to rise.
Leya said the benefits of drug-coated stents outweigh risks, which include re-clogging of the arteries or having to re-implant bare metal stents, as well as risks from the angioplasty procedure itself.
The FDA has convened a special panel for next week to look at the clotting issue. The meeting was scheduled to discuss heart devices, but the clotting issue has prompted the FDA to call additional outside experts in to be a part of the discussion. The FDA has not yet disclosed the list, but leading experts in cardiology, drug and device safety are expected. The panel could recommend labeling changes to drug-coated stents. The FDA usually follows recommendations of its panels.
For its part, Abbott believes newer drug-coated stents, like the Xience model it hopes to have on the U.S. market by 2008, could be safer. An Abbott-funded study earlier this year showed Xience had a thrombosis rate of 0.5 percent at six months' usage compared with a 1.3 percent rate for Boston Scientific's Taxus.
Abbott and doctors say all stents are different and should not be lumped in the same bucket when searching for a cause to the clotting issue. Stents have different drug coatings and are implanted with different systems.
"It's not just any one component of a drug-eluting stent that matters it's the whole system," said Abbott spokeswoman Kelly Morrison.
Until Abbott's drug-coated stent hits the market, analysts say the company could benefit in a return to bare metal stents, which it sells as part of its purchase of Guidant. "We have seen a small uptick in bare metal stents in the last few months," said Morrison.
Leya said drug-coated stents reduced the tendency for arteries to re-clog to just 5 percent to 10 percent of patients, compared with 20 percent to 25 percent for the bare metal variety. By comparison, 30 percent to 50 percent of patients who simply had an angioplasty procedure eventually had their arteries re-clog, he said.
Although no one is certain about what causes the clotting issues, cardiologists think some of it may be due to patients not taking their medications to reduce the risk of clots. .
Doctors say they encourage patients who have drug-coated stents to take aspirin and a common anti-clotting drug known as Plavix for up to six months or longer. The pills can cost $3 to $4 a day if they do not have drug coverage.
"A combination of aspirin and Plavix is extremely important," said Rush's Schaer. "We are more conservative about using the drug-coated stents in patients who are less compliant ."