UPDATE 2-Abbott stent superior to Boston Sci after 3 yrs-study

* Xience stent keeps low cardiac death rate at 2 to 3 yrs

* Taxus stent death rate rises to 4.2 pct from 1.3 pct

* MACE rate 57 pct lower with Xience at 3 years (Adds detail about TriLipix)

By Bill Berkrot

NEW YORK, March 29 (Reuters) - Safety advantages of Abbott Laboratories' (ABT.N) Xience stent over Boston Scientific Corp's (BSX.N) rival Taxus stent increased between two and three years, according to long-term data presented on Sunday.

The data showed that patients treated with Xience experienced fewer heart attacks, deaths or need for repeat procedures at the stenting site by an increasing margin compared with patients treated with Taxus three years after the stents were initially placed, researchers said.

The latest data from the 300-patient Spirit II trial, unveiled at the American College of Cardiology scientific meeting in Orlando, followed previous data comparing the two drug coated stents after six months, one year and two years.

Separately on Sunday showed that a combination of Abbott's new TriLipix triglycerides medicine and a low dose of AstraZeneca Plc's (AZN.L) Crestor cholesterol drug worked better than the individual pills in helping improve heart risk factors [nN27436261].

Stents are tiny mesh tubes used to prop open arteries that have been cleared of plaque. The medicines coating the stents help to prevent reclogging.

Between two and three years, Xience maintained its low cardiac death rate of 0.5 percent, while the rate among Taxus patients rose from 1.3 percent at two years to 4.2 percent at three years, researchers said.

On the composite measure of major adverse cardiac events (MACE) -- cardiac death, heart attack and need for revascularization -- Xience maintained a rate of 6.4 percent between two and three years. The Taxus MACE rate increased about 40 percent from 10.5 percent at two years to 14.9 percent at three years.

Three years after stent placement there was a statistically significant 88 percent reduced risk of cardiac death with Xience compared to Taxus and a 57 percent MACE risk reduction, researchers said.

For Xience there was also a statistically significant lower risk of stent thrombosis, or formation of dangerous blood clots, with no incidence of stent thrombosis in the Xience patients between two and three years.

"It's positive to see the performance sustained, and with the curves continuing to favor Xience, it's a very strong result," said John Capek, Abbott's executive vice president for medical devices.

In addition to Taxus, Boston Scientific sells a version of Xience under a different name. Xience was originally developed by Guidant Corp, which was acquired by Boston Scientific in 2006. Boston sold Guidant's stent business to Abbott, but retained the right to sell Xience under the Promus brand name with 40 percent of the profit going to Abbott. (Additional reporting by Martinne Geller; Editing by Bernard Orr and Steve Orlofsky)