ACC: Late-term results may be evening out for Endeavor stent

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While the angiographic late lumen loss is greater with Medtronic’s Endeavor stent compared with Cordis’ Cypher stent, the rates of target lesion revascularization (TLR) are stabilizing and the absolute differences between the stents in clinical restenosis are decreasing over the long term, according to the five-year results from the ENDEAVOR III trial presented as a scientific poster during ACC.10 in Atlanta last week.

In the 3:1 randomized trial to confirm the safety and efficacy of the Medtronic zotarolimus-eluting stent in de novo native coronary artery lesions, ENDEAVOR III enrolled 436 patients (Endeavor, 323 patients; Cypher 113) at 30 U.S. sites.

David Kandzari, MD, director of interventional cardiology research at the Scripps Clinic in La Jolla, Calif., and colleagues sought to determine whether results of the Endeavor drug-eluting stent (DES) in a U.S. PCI population were similar to those observed in the Endeavor trials conducted internationally. The researchers also sought to determine whether eight-month angiographic outcomes (in-segment late loss) with the Endeavor DES are non inferior to the FDA-approved Cypher sirolimus-eluting stent.

Out of the initial patient population, at five years, the eight-month angiographic follow up was 85.8 percent in the Endeavor arm (277/323), and 83.2 percent in the Cypher arm (94/113). At five years, the clinical follow up was 80.6 percent in the Endeavor arm (307/323), and 86.8 percent in the Cypher arm (108/113).

For the angiographic and intravascular ultrasound results at eight months, the in-segment late loss with Endeavor was 0.36 mm, compared with 0.13 mm in the Cypher arm. Also, the percentage of volume obstruction was 15.9 percent in the Endeavor arm and 2.7 percent in the Cypher arm.

For the clinical outcomes at five years, all-cause mortality was 5.2 percent with Endeavor (16 patients) and 13 percent with Cypher (14 patients). Meanwhile, cardiac death was reported at 0.3 percent with Endeavor (one patient) and 2.8 percent with Cypher (three patients). For MI, the reported incidence was 1 percent with Endeavor (three patients) and 4.6 percent with Cypher (five patients) at five years.

However, for both definite and probable stent thrombosis, there were two incidence in the Endeavor arm and one incident in the Cypher arm, according to the researchers.

For TLR, the authors reported that the Endeavor stent arm had higher rates—with 8.1 percent (25 patients), compared with 6.5 percent in the Cypher arm (seven patients). Likewise, the Endeavor stent arm had higher comparative rates to the Cypher stent arm for target vessel revascularization—16.9 percent (52 patients) versus 13 percent (14 patients).

However, for major adverse coronary events (MACE), the Endeavor arm (14 percent, 43 patients) was lower than the Cypher arm (22.2 percent, 24 patients).

Based on the results, Kandzari and colleagues, recognizing the limitations in sample size, concluded that the late-term (five years) follow-up of the Endeavor stent demonstrates durability in efficacy (TLR); low rates of very late stent thrombosis (one event); and compared with the Cypher DES, emerging differences in cardiac death/MI and MACE achieving statistical significance.