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April 22, 2008 -- The new Xience stent beat the popular Taxus stent in a one-year trial, but experts disagree on whether stent science is moving too fast.
Stents prop open arteries that have been unclogged by balloon angioplasty. Bare-metal stents tend to reclog more often than drug-coated stents. Doctors were very quick to start using drug-coated stents, even in patients with far more complex heart disease than the patients in whom the devices were tested.
Recently, doctors were blindsided by the discovery that blood clots can form at the site of drug-coated stents long after implantation. This led to significant confusion, which is only just now settling down as doctors better learn how to prevent these clots.
Now Xience, a new stent with a new kind of drug coating, seems safer and more effective in a one-year clinical trial. Should the FDA approve it? Or should history make the FDA wait until more is known?
Manesh Patel, MD, assistant professor of cardiology at Duke University, argues for caution.
"We want a durable result with the device we use. That is the conundrum in a rapidly moving science," Patel tells WebMD. "We have new devices that may be safer and more effective, but we need time to see how well they reduce long-term events."
Gregg W. Stone, MD, director of cardiovascular research and education at the New York Presbyterian Hospital/Columbia University's Center for Interventional Vascular Therapy, led the 1,002-patient study of the new stent.
Stone says it's already known that drug-coated stents -- doctors call them drug-eluting stents -- work better than bare-metal stents in most cases. Yet two-thirds of the time, he says, they are used in patients who have more complex heart disease than the patients for whom the stents are officially approved.
"Physicians have to use their judgment, based on what they know and on the studies that have been done, to decide whether the use of a drug-eluting stent is in the individual patient's best interest," Stone tells WebMD. "I don't think this new stent is going to markedly change how doctors use stents. It will just convert doctors who have used earlier stents to this one because the outcomes look safer and more effective."
The new Xience stent is coated with a different drug than is used in other stents. When compared to the most popular stent now in use, the Taxus stent, patients who got the new stent had less reclogging of the arteries and fewer heart attacks or repeat procedures over a year of follow-up.
"Compared to the most widely used stent in the world, the outcomes for the new stent in some regards appear safer and more effective," Stone says. "We anticipate FDA approval over the next several months."
Patel hopes doctors will learn from their earlier experience.
"What happens next is critical," he says. "Will we have learned from the two main lessons of the past: Will doctors show restraint, and put these stents only in the type of patients who have been studied? And will we do the longer studies to show they work?"
The Stone study, and an editorial by Patel, appear in the April 23/30 issue of The Journal of the American Medical Association.
Abbot Vascular, maker of the Xience stent, sponsored and funded the study. Stone, who is a senior investigator in many clinical trials, has received research support and/or honoraria from Roche Vascular and from other stent manufacturers.