Drug-Coated Stents Show Shortfalls
Real-life results below those in controlled trials, study finds
TUESDAY, May 3, 2005 (HealthDay News) -- Drug-coated stents, the metal tubes surgeons insert to keep arteries open, aren't proving as effective in real-life medical practice as they did in carefully controlled trials needed for regulatory approval, a new European study finds.
The rate at which blood vessels closed up again after artery-opening procedures and stent implantation was at least double that reported in controlled trials, according to a report in the May 4 issue of the Journal of the American Medical Association. The study included more than 2,000 patients treated at hospitals in Germany and Italy.
But another report in the same issue of the journal gave tentative thumbs-up for the use of coated stents in an exceptional situation -- just after a major heart attack.
The real-life report, led by cardiologists at the Columbus Heart Center in Milan, looked at stents coated with two different drugs, sirolimus and paclitaxel, both designed to prevent clots that can block arteries.
Nine months after implantation, the rate of artery blockage was 0.8 percent for patients who got the sirolimus-coated stents and 1.7 percent for those who got stents coated with paclitaxel. Not bad, but the rate in the controlled trials was much less: 0.4 percent for sirolimus and 0.6 percent for paclitaxel, the report said.
According to the researchers, one possible reason for the higher rate was that cardiologists relied too much on the stents, ending treatment with other clot-preventing drugs prematurely. Twenty-nine percent of the patients in whom anti-clotting therapy was stopped too early had their arteries close up again, they noted.
"This is pretty much the accepted norm," Dr. Warren K. Laskey, chief cardiologist at the University of New Mexico, said of the study results. "There is always an enormous blip of early enthusiasm early on which settles down to sober reality."
Cardiologists must remember that drug-coated stents "are not magic bullets," Laskey said. "They need to be used carefully, in exactly the way that is described by the FDA [U.S. Food and Drug Administration] in the product labeling. Departures from that are at the risk of physicians and patients."
Dr. Eric Topol, chairman of cardiovascular medicine at the Cleveland Clinic, agreed that the real-life results weren't surprising. "When you look at the real world, patients are at higher risk and there is more clotting," Topol said, adding that first reports of a new medical technology are always enthusiastic.
"The average cardiologist gets a misimpression," Topol said. "There can be a state of complacency that things are better than they actually are. You can't let your guard down."
Topol gave a guarded thumbs-up for the second study, on the use of stents after a heart attack.
That study, led by cardiologists at the University of Ferrara in Italy, compared results of two different strategies. Some heart attack patients got bare-metal stents and an expensive clot-preventing drug, abcixamab, while others got sirolimus-coated stents and a less expensive clot-preventer, tirofibam. Only 14 of the 74 patients who got the coated stent had serious trouble, ranging from closing of the artery to death, compared to 37 of the 74 patients who got the bare-metal stents.
"The results favor coated stents for such major events, and that is good news," Topol said. "But it is a small trial, with only 148 patients, so it is hard to make strong conclusions from it."
The fact that the pairing of a more-expensive stent with a less-expensive clot-preventing drug gave improved results is "intriguing," Topol said. There have been speculations and anecdotal reports about the use of coated stents after a heart attack, and this study supplies some data to support their use, he said. But more controlled trials are needed to prove or disprove the point, Topol said.
The use of stents is explained by the American Heart Association.