Drug-eluting stents proving their power in staving off restenosis

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Drug-eluting stents outperform the current “gold standard” radiation treatment in managing coronary restenosis and in preventing consequent clogging of coronary arteries, according to the first published trial of its kind. The multi-center clinical study titled“A Prospective, Multicenter, Randomized Trial Evaluating the TAXUS Paclitaxel-Eluting Coronary Stent versus Vascular Brachytherapy for the Treatment of Bare Metal Stent In-Stent Restenosis: The TAXUS-V ISR Trial” was presented this week at the American College of Cardiology annual meeting in Atlanta.

When a plaque-filled coronary artery is opened and treated with a regular metal stent, it has a one-in-three chance of narrowing again due to scar tissue. But the results of this multicenter, randomized trial provide new insight into the comparative effectiveness of drug-eluting stents and radiation therapy for restoring blood flow through the blocked coronary stent.

Vascular brachytherapy (VBT) — or irradiation inside the narrowed artery — is the only therapy approved by the FDA for in-stent restenosis (ISR). However, brachytherapy is time-consuming, not widely available, and has been shadowed by complications. In the TAXUS-V ISR study, Gregg W. Stone, M.D., F.A.C.C., of Columbia University Medical Center and the Cardiovascular Research Foundation, New York City, and fellow researchers from 37 North American medical centers set out to determine whether the TAXUS drug-eluting stent might offer a better alternative to VBT. Slow release of paclitaxel from the stent’s surface has been shown to inhibit new growth of scar tissue in other types of patients, but its effectiveness against in-stent restenosis is unknown.

The study enrolled 421 patients with in-stent restenosis, randomly assigning them to VBT or repeat stenting with the TAXUS stent. After 30 days, the two approaches appeared to be equally safe, with similar rates of cardiac death, heart attack, coronary procedures, and blood clotting in the stent. Investigators also evaluated clinical outcomes after nine months of followup which showed a reduction of 40 percent in the number of patients needing additional procedures to clear the artery compared to vascular brachytherapy. Angiographic measures in both groups showed that patients who had drug-eluting stents experienced half as much restenosis (14.5 percent) as those who had brachytherapy (31.2 percent). The stents also were found to reduce major cardiac events from 20.1 percent in the brachytherapy group to 11.5 percent. The two treatments had similar rates of cardiac death or myocardial infarction (5.2 percent for brachytherapy and 3.7 percent for stenting) and thrombosis in the stented artery (2.6 percent for brachytherapy and 1.6 percent for stenting).

“The results are what everyone was hoping for,” Stone said. “Drug-eluting stents should now be considered the standard of care for most patients with restenosis of previously implanted bare metal stents, and radiation treatment should be abandoned.”

The study also is being published in the March 15th issue of the Journal of the American Medical Association.
   
Other trials in the past few years have shown drug-eluting stents to be superior to bare metal stents in preventing restenosis, when used for initial stent placement inside a coronary artery. Another study presented at ACC, “The Randomized Comparison of Paclitaxel Eluting Stent Versus Conventional Stent in ST-segment Elevation Myocardial Infarction (PASSION) Study,” focused on patients with the most serious form of heart attack, ST-segment elevation myocardial infarction (STEMI). Mauritis T. Dirksen, MD, and his colleagues from the Amsterdam Department of Interventional Cardiology, OLVG, in the Netherlands, randomly assigned 620 patients with acute STEMI to artery-opening treatment with either conventional bare-metal stent or a drug-eluting stent. After one year, they compared the combined rates of death, repeat MI and repeat catheter-based interventional or bypass surgery on the heart-attack-related artery. A preliminary six-month followup showed that the drug-eluting stent reduced the rate of repeat procedures in or near the stent to just 1 percent, as compared to 3.6 percent with the bare metal stent.