Medtronic’s new drug coated stent, Endeavor, still faces some serious questions about its effectiveness, after a long-anticipated study showed that the device had only mixed success in meeting some performance goals. The new data was released just days before Endeavor undergoes a regulatory review, the outcome of which could help determine if the Medtronic stent is approved by the Food & Drug Administration (FDA).
Drug coated stents were developed as a way to keep blood vessels open after an angioplasty. Stents are lattice-like devices that act like scaffolding to hold a blood vessel open. The drug coating is supposed to keep scar tissue from re-narrowing the artery, a common problem with the bare metal stents.
There are currently two drug coated stents approved for use in the US, Boston Scientific’s Taxus and Johnson & Johnson’s Cypher. But both these stents have had safety issues of their own. In 2006 the Cleveland Clinic published an analysis of fourteen stent studies covering more than 6,000 patients that found those with drug coated stents were four to five times more likely to suffer from blood clots than those implanted with bare metal stents. Since then, several other studies have also shown that some patients receiving drug eluting stents also had higher rates of blood clots.
Medtronic has sought approval for its Endeavor stent, in part by claiming that the device was less likely than either Taxus or Cypher to cause late-developing blood clots. Late last week, Medtronic released data from a long term study of the stent called “Endeavor IV”. While the study did indicate that Endeavor performed well over the long-term, it also found that patients receiving the Medtronic stent might be at a somewhat higher risk of developing earlier blood clots.
The study compared 1,548 patients who had received either an Endeavor or Taxus stent. At nine months, Endeavor had a 0.8% rate of stent-related clots compared with 0.1% for Taxus. There were six cases of such clots for Endeavor within 30 days of the device’s implantation. Three clots occurred between 1 and 6 months after the patients received an Endeavor stent.
Overall, this latest study found that Endeavor stent did do a better job than Taxus of avoiding heart attacks and cardiac deaths. But the Endeavor stent did not meet a secondary goal, which was to do as well as, if not better than, Taxus in preventing an artery with a stent from narrowing again.
Tomorrow, the FDA will convene a panel of outside advisors to recommend whether or not the Medtronic Endeavor stent should be approved. The panel will consider the data from the Endeavor IV study as part of that review. According to a recent Wall Street Journal report, most analysts still expect that the new Medtronic stent will be approved, but others have called the results of the Endeavor IV study a disappointment.