CHICAGO -(Dow Jones)- New two-year data on Abbott Laboratories Inc.'s (ABT) Xience drug-coated stent indicated continued positive performance when it came to avoiding heart attacks and other major issues in a match-up with a Boston Scientific Corp. (BSX) stent, although the gap in performance is no longer considered significant.

The change is linked to the 300-patient study's small size and the fact the study wasn't designed to actually show significantly better performance when it comes to patients avoiding major events, said Patrick Serruys, professor of interventional cardiology at Thoraxcentre Erasmus University Hospital in Rotterdam and the trial's principal investigator. But the trends were still positive and in Xience's favor, he said.

In general, the difference in performance between the stents "has remained pretty much unchanged," Serruys said in an interview.

A subset of the 300-patient Spirit II randomized trial on Abbott's stent showed, meantime, that Xience, which formerly performed better than Boston Scientific's Taxus device when it came to a certain measure of artery renarrowing, was about the same as Taxus at two years. Boston Scientific also sells Xience under the brand name "Promus" under a profit-sharing deal with Abbott.

The study data were set for presentation early Monday at the Society for Cardiovascular Angiography and Interventions annual meeting, which is being held alongside the American College of Cardiology's conference this year. The Abbott- backed study assessed patients in Europe, New Zealand and India. Xience, which went on sale outside the U.S. in late 2006, was matched up against Taxus, the top-selling coated stent in the U.S.

Abbott is expecting the Food and Drug Administration to approve Xience for sale in the U.S. in the second quarter. A panel of outside experts recommended late last year that the device be approved. FDA approval would also clear Boston Scientific's version, called Promus, for U.S. sale.

The Xience recommendation came despite some questions on Wall Street about whether Abbott had the longer-term evidence the FDA wanted due to concerns about links between coated stents and late-developing, dangerous clots. The call for longer-term data casts a spotlight on any new releases from Abbott, which is trying to become the fourth company to enter the U.S. coated stent market, after Johnson & Johnson (JNJ), Boston Scientific and Medtronic Inc. (MDT).

Heart stents are implanted during angioplasty procedures to keep clogged arteries open, and coated devices such as Xience and Boston Scientific's Taxus use medication to combat renarrowing.

The Spirit II study was randomized so that three patients had a Xience stent for every one with a Taxus device. The study showed that at two years, the rate of "Major Adverse Cardiac Events," or MACE, was 6.6% for Abbott, compared with 11% for Taxus. That represents a 40% difference in favor of Xience, although the gap is not considered statistically significant. After one year, the gap in performance was wider and was considered significant.

In another area, a measure of "late loss," or narrowing in the stented area, the advantage Abbott's stent held early on slipped away, at least among the subset of 117 patients whose arteries were imaged with an angiogram. That test showed a late loss rate of 0.33 millimeters for Xience and 0.34 millimeters for Taxus at two years.

The Spirit II trial was originally intended to show performance on in-stent late loss at six months, at which point Xience performed better than Taxus. "The advantage with late-loss has been lost with time," Serruys said.

But he noted that this narrowing didn't translate into clinical events. When it came to the need for retreatment in the stented area driven by lack of blood supply, there was a 3.8% rate at two years with Xience, compared with a 6.8% rate with Taxus.

Charles Simonton, divisional vice president, medical affairs, and chief medical officer at Abbott, said in an interview that the change in late loss was "kind of expected" with Xience, which essentially elutes all the drug it uses to combat renarrowing several months after implantation. The medication is needed during that early post-stent period, when growth around the device is more of an issue.

Simonton also noted the small size in the subgroup of patients studied with an angiogram, which had 85 Xience patients and just 32 Taxus patients.

-By Jon Kamp, Dow Jones Newswires; 312-750-4129; jon.kamp@dowjones.com

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  03-31-08 0915ET
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