If the Old Stent Failed, So Will a New One
Study finds re-stenting futile even if arteries are radiated
TUESDAY, May 14, 2002 (HealthDayNews) -- If a stent doesn't help keep your arteries flowing, then having a new one put in is likely to fail, too.
A new study on the devices shows the futility of fixing a failed fix. Installing a second stent in a patient whose old one didn't work also didn't help, even if the patient's arteries were radiated for good measure. The study, from Stanford University, appears in the May 28 issue of Circulation.
Stents are tiny tubes used to prop open arteries that have been cleared by angioplasty. The problem is that, in about one-fifth of patients, the stents actually cause smooth muscle cells to proliferate, resulting in yet another blockage of the artery. This re-narrowing of the blood vessels is called in-stent restenosis.
The recent study is the latest in a series to show that adding a second stent does not solve the problem. Nor does radiation (brachytherapy) improve long-term outcomes in people who have received a second stent.
"The bottom line of the study is whether the patients have been treated with brachytherapy or not, those in-stent restenosis patients don't do well with a stent sandwich -- a stent inside a stent," says study author Dr. Peter Fitzgerald, an associate professor of medicine and director of the Cardiovascular Core Analysis Laboratory at Stanford. "They don't respond well to an additional metallic scaffold. A stent can really look good for a while, but it complicates things."
This study corroborates previous research.
"It's just another way of looking at the same problem," says Dr. Jeffrey Moses, chief of interventional cardiology at Lenox Hill Heart and Vascular Institute in New York City. "Clinically, we've known this all along."
What is new in this study is the use of ultrasound to measure lumen volume index, or LVI. Higher LVI indicates that blood is flowing more easily through the vessel.
A team led by Dr. Yoshihiro Morino looked at 70 patients with in-stent restenosis. Of these, 34 patients had received radiation in the re-narrowed arteries while 36 had received no radiation. The 34 patients in the radiation group were divided into four subsets: an old stent not re-stented; an overlap of an old and a new stent; a new stent only; and lesions treated without re-stenting.
In patients treated with radiation as well as those in the placebo group, the lumen volume was initially higher but the benefit disappeared after six months. Re-stented areas that had been treated with radiation were almost twice as likely to have new cell growth.
"It's a reaction to the stent," Fitzgerald says. "We're being overwhelmed by a biologic process in 20 to 25 percent of cases when we put in a mechanical device, so there's no reason to come back with another mechanical device."
That takes care of what not to do. However, what would work?
Fitzgerald says stents that deliver drugs to inhibit the new cell growth are the wave of the future. "The drug impacts the biology directly rather than just relying on a mechanical device," he says.