Abbott stent outperforms but not in diabetics-study

* Xience reduced serious stent complications by 38 percent

* No difference in Xience vs. Taxus in diabetics

* Xience reduced stent thrombosis, or clots, by 74 percent

By Susan Kelly

CHICAGO, Sept 23 (Reuters) - Abbott Laboratories' (ABT.N) Xience V heart stent outperformed rival Boston Scientific's (BSX.N) older Taxus Element stent on a measure of safety and effectiveness in a large study, but did not show a significant advantage in diabetic patients.

The Spirit IV study, which was presented Wednesday at a meeting of interventional cardiologists in San Francisco, offered more evidence of clinical strengths that have helped make Xience the top-selling drug-eluting stent.

Stents are tiny wire-mesh scaffolds used to prop open narrowed or blocked arteries. Medicines coating the stents help to prevent re-clogging.

In the study of 3,690 patients, Xience demonstrated a 38 percent reduction in death, heart attack and certain repeat procedures compared to Taxus on the main clinical goal of target lesion failure, a composite measure of major cardiac complications.

Target lesion failure occurred in 4.2 percent of the Xience patients one year after implantation, compared to 6.8 percent of the Taxus patients.

Patients with the Xience stent also had a statistically significant 46 percent reduction in repeat procedures at one year on a secondary goal called target lesion revascularization, which occurred in 2.5 percent of Xience patients vs. 4.6 percent of Taxus patients.

For Xience, the study also showed a 74 percent lower rate of stent thrombosis, or dangerous blood clots. Risk of blood clots has been a chief concern of interventional cardiologists in recent years and has led to some scaling back in the use of drug-eluting stents.

Stent thrombosis occurred in 0.3 percent of the Xience patients, compared to 1.1 percent with Taxus.

"The Spirit IV results show that Xience V significantly reduces a patient's risk of experiencing a heart attack, the need for a repeat procedure or stent thrombosis," said Dr. Gregg Stone, professor at Columbia University Hospital and the study's author, who presented the data at the Transcatheter Cardiovascular Therapeutics annual meeting.

Yet in a much-anticipated subset of about 1,100 patients with diabetes, there was no statistically significant difference in target lesion failure between Xience and Taxus at one year, with 6.4 percent of Xience patients experiencing those events vs. 6.9 percent for Taxus.

Results from the diabetes group have been eagerly awaited because of the large number of patients studied. Boston Scientific has claimed its Taxus stent produces superior outcomes in diabetics, who are typically sicker and whose artery disease can be more complicated to treat.

"Outcomes in patients with diabetes may still be improved, and should represent an area of focus for future development of novel drugs and enhanced stent design," Stone said.

Wall Street analysts have estimated the value of the U.S. drug-eluting stent market at about $2 billion.

According to data from J.P. Morgan, Xience leads the market with about a 29 percent share. Boston Scientific's Promus stent, which is the Xience stent licensed from Abbott, has about one-quarter of the market. Boston Scientific's Taxus has a 22 percent share, Johnson & Johnson's (JNJ.N) Cypher has 14 percent of the market and Medtronic's (MDT.N) Endeavor has 11 percent.

Boston Scientific's Taxus Liberte stent, which was introduced in Europe in 2005 and in the United States a year ago, has largely replaced the Taxus Element product in terms of sales. (Reporting by Susan Kelly, editing by Dave Zimmerman)