When it comes to their clinical effect, “we know that most patients can accommodate a certain amount of stenosis before it overwhelms their coronary flow reserve,” said Dr. Stone. “The target lesion revascularization rate is only 7% when late loss is 0.70 mm. A 0.62-mm late-loss rate would not be expected to cause much target-lesion revascularization,” he said.
“Late loss is significantly greater [with the Endeavor stent] than with other drug-eluting stents, but it is still low enough to produce excellent freedom from restenosis,” Dr. Stone concluded.
Another factor is that the ENDEAVOR II study mostly used patients with a low relative risk for target-lesion restenosis. If the stent is tested in higher-risk patients or in higher-risk lesions, such as those in narrow coronary arteries, it's possible that the higher rate of late loss will make a clinical difference, commented Laura Mauri, M.D., a cardiologist at Brigham and Women's Hospital in Boston.
Nonetheless, the Endeavor stent may have other attributes that make it an attractive option. The Driver bare-metal stent that's the platform for the ABT-578-eluting stent is widely regarded as easy to use. Plus, the Endeavor stent uses a biocompatible phosphorylcholine coating that binds the drug layer to the metal stent. The sirolimus- and paclitaxel-eluting stents use a polymer coating. The phosphorylcholine coating may explain why the rate of late thrombosis in the ENDEAVOR II study was so low, 0.5%. The polymer coats on the other drug-eluting stents may, in part, be why they have led to some problems with late thrombosis, Dr. Mauri said. But a study designed to definitively show whether these stents differ in their rate of late thrombosis would require several thousand patients.
