In anticipation of receiving FDA approval by year’s end for its Endeavor drug-eluting stent (DES), Medtronic presented Endeavor IV clinical trial findings this week at the Transcatheter Cardiovascular Therapeutics meeting in Washington, D.C. In response, a panel of cardiologists questioned the methods of the study and discussed the safety of the stent.
The “drug release [of Endeavor’s Zotarolimus] is more rapid” than its competitors, Cordis and Boston Scientific, because “most of the drug is released in 14 days,” said Martin Leon, MD, of Columbia Medical Center in New York City who represented on Medtronic’s behalf. He did, however, concede that Endeavor “needs more and longer studies.”
The Endeavor IV clinical trial included 1,548 patients, 773 of which had the Endeavor stent implanted, and the other 775 who had the Boston Scientific’s Taxus stent implanted, according to Leon. The vessel diameter was between 2.5mm and 3.5mm. The primary endpoint for the study is target vessel failure (TVF) at nine months.
Of 144 patients who received an Endeavor stent, 19 patients, or 13.3 percent, had an occurrence of in-stent restenosis. For 135 patients with the Taxus stent, nine patients, or 6.7 percent, had an occurrence of in-stent restenosis.
Leon reported that the primary endpoint at nine months for TVF was 6.6 percent for Endeavor and 7.2 percent for Taxus. He said there was significant TVF difference at 12 months, but “Endeavor’s results remain lower.”
In addition, two patients implanted with the Endeavor stent died, while no patients implanted with Taxus died. Leon stressed that these deaths were not attributed to the stent.
Leon concluded that Endeavor reduced peri-procedural complications, and Endeavor’s statistics were similar to Taxus in its overall safety profile for larger complications such as death and myocardial infarctions (MI).
In response to Leon’s presentation, Patrick Serruys, MD, chief of interventional cardiology at Thoraxcenter-Erasmus University in Rotterdam, Netherlands, said that the Endeavor study had “obvious conflicts,” and questioned the methodologies of the study.
Serruys said Endeavor met its non-inferiority primary endpoint of TVF at nine months in comparison to the Taxus stent. However, Serruys disagreed with that method of TVF as a sole primary endpoint, because he believed the primary endpoint should be a composite of TVF, death and MI as well.
In conclusion, Serruys reiterated his skepticism of about Endeavor’s efficacy.
Despite some disagreements on methodology, the entire panel reached consensus that more investigation into the Endeavor stent needs to be conducted.