Doctors fear Abbott and Medtronic stents will not be safer, though easier to insert

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Two new drug-eluting stents from Abbott Laboratories and Medtronic are expected to enter the market may be easier for surgeons to insert, but their safety and efficacy profiles will be comparable to their predecessors, physicians told Pharmawire.

The physicians added that the overall use of stents has declined, as patients are screened for their ability to comply with a long-term anticoagulant regimen.

Last month, the Circulatory System Devices Advisory Panel to the FDA recommended approval for Abbott Laboratories’ Xience V and Promus everolimus-eluting coronary stent systems. Both stent systems would be covered by the same FDA approval.

In October 2007, a federal advisory panel unanimously recommended that the FDA regulators approve Medtronic’s Endeavor drug-eluting stent, along with a requirement for follow-up safety studies. The FDA usually follows the recommendations of its advisory panels, but is not required to.

If these stents are officially approved by the FDA, Abbott and Medtronic will join the only other drug-eluting stent (DES) manufacturers on the U.S. market – Boston Scientific and Cordis, a subsidiary of Johnson & Johnson.

Pharmawire reported that the DES category, including Cordis’s Cypher and Boston Scientific’s Taxus, came under scrutiny last year when researchers noticed an increased risk of blood clots with the devices compared to bare-metal stents.

Cardiologists are unsure whether blood clots result from an inflammatory response to the polymer, or because the attached drug delays the healing process, leaving the metal exposed in the artery for a longer period of time.

“I believe that technology will overcome these problems,” Dawn Abbott, MD, a stent researcher and interventional cardiologist at Brown Medical School told Pharmawire. However, she does not “think the next generation of stents that become available to us will make a difference.”

Paul Gurbel, MD, director of the Sinai Center for Thrombosis Research, similarly responded to Pharmawire negatively when asked whether the next generation of stents would overcome the problems. “I don’t know any data that would rigorously support the use of one drug versus another,” he said.

Yet, Allen Jeremias, MD, director of vascular medicine and peripheral intervention at the State University of New York, Stony Brook, told Pharmawire that the newer stents have “theoretical benefits” because they are thinner and easier to insert. Endotheliazation - the aforementioned healing process - might also be quicker with a thinner stent, he added.

The devices themselves offer trade-offs, physicians noted to Pharmawire. The Endeavor stents seems to be associated with less late-stage thrombosis, but more late loss or tissue growth inside the blood vessel in the months after the procedure, the physicians said. The Endeavor’s zotarolimus coating is the least potent agent for repressing restenosis, according to Jeremias.

Abbott stressed that it is still unclear whether the differences will translate into different clinical outcomes for patients. Abbott noted to Pharmawire that the use of DES reached its peak in 2005, when 94 percent of patients undergoing cardiac catheterization received them. Their usage has since fallen to about 60 to 70 percent, she estimated, largely because of greater screening procedures. “I think there’s a greater awareness of looking at the risk-benefit ratio in individual patients,” she said.

DES does reduce the risk of restenosis by 50 percent compared to bare-metal stents; the risk of developing thrombosis is 0.2 to 0.4 percent, she added.

“The drug-eluting stents are back, but the patients are screened more carefully for their ability to take dual anti-platelet therapy,” Jeremias said.