UPDATE 2-AstraZeneca drug tops Plavix in sickest patients

* Astra's Brilinta tops Plavix in heart attack patients

* No increased major bleeding risk seen with Brilinta

* 18 pct reduction in all cause death seen with Brilinta

* Data from sickest 40 pct from larger PLATO trial (Add further researcher comment)

By Bill Berkrot and Ransdell Pierson

ORLANDO, Fla., Nov 15 (Reuters) - Heart attack patients in need of emergency procedures were less likely to suffer further serious cardiovascular events, including death, when given AstraZeneca's experimental Brilinta blood clot preventer than those who used Plavix, according to a study presented on Sunday.

Importantly, the Brilinta patients also were found to be at no greater risk for major bleeding than those taking Plavix -- an encouraging sign for such drugs that work by preventing blood cells called platelets from clumping together.

The lack of increased bleeding risk seen with AstraZeneca's (AZN.L) new medicine could provide comfort that safety was not compromised in order to obtain its greater ability to prevent cardiovascular death, heart attack and stroke for up to a year.

The findings are an important new slice of data from a more than 18,000-patient comparative international trial called PLATO unveiled earlier this year in which Brilinta also proved superior to Plavix, one of the world's most widely used medicines sold by Bristol-Myers Squibb (BMY.N) and Sanofi-Aventis (SASY.PA) with annual sales of some $9 billion.

Analysts see Brilinta as a potential multibillion-dollar a year seller for AstraZeneca, which plans to file an application seeking U.S. approval later this year.

For the latest data, researchers focused on the 8,430 sickest patients in the PLATO trial -- those in the midst of so called ST-elevation heart attacks with total obstruction of at least one coronary artery who were in need of emergency angioplasty and stents to restore blood flow and save heart muscle.

"The results are very clear and actually very consistent with the overall trial results of the larger PLATO trial," preventing cardiovascular events while not increasing the major bleeding risk, said Dr. Philippe Gabriel Steg, lead investigator of the study that was presented at the American Heart Association scientific meeting in Orlando.

Steg said Brilinta, known chemically as ticagrelor, works much more quickly than Plavix, which could be an advantage in these patients in whom time to performing an artery clearing procedure is crucial.

"Clopidogrel's drawbacks include slower onset of effectiveness, which is not suited to the need for rapid effect in STEMI (ST-elevation heart attacks)," Steg said, using the chemical name for Plavix.

DEATH REDUCTION

According to the latest findings, 9.3 percent of patients receiving Brilinta suffered cardiovascular death, heart attack or stroke for up to a year, compared with 11 percent in the Plavix group, a statistically significant difference, researchers said.