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 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 and Sanofi-Aventis 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.

There was an 18 percent relative reduction in death from any cause at one year in the Brilinta group, they said.

This sets apart this drug and this study from all other oral agents studied so far, Steg said.

In previous trials, other oral agents prevented cardiovascular events, but did not significantly reduce mortality, added Steg, who said the Astra drug could become a standard of care for managing very high risk patients undergoing angioplasty procedures.

He said the survival benefit suggests Brilinta may be protecting patients through mechanisms that are not yet known.

For these sickest heart patients in the study, the benefits seen with Brilinta increased over time, researchers said.

Another advantage demonstrated by Brilinta that could help once it begins competing with one of the world's top-selling medicines is how quickly its effects wear off.

Researchers said once the medicines are stopped, normal platelet clotting ability returns in fewer days than with the Astra drug, which could provide a real clinical difference in patients in need of more serious invasive procedures in which bleeding is a serious risk.

However, there are a couple of issues potentially standing in Brilinta's path to swift approval.

As seen in previous Brilinta studies, there was a higher incidence of breathlessness -- 12.9 percent versus 8.3 percent with Plavix -- that could be a signal of unintended impact on lung function. Steg said that side effect was mild and went away after a few days after the start of treatment.

There also was an as-yet-unexplained lack of benefit over Plavix seen in North American patients, who accounted for about 9 percent of total PLATO subjects but who would represent the most important market for the drug's future success.

There has been speculation that higher doses of aspirin being taken by U.S. patients in the study could account for the disparity, or that it was merely a statistical fluke.

But it is likely something the U.S. Food and Drug Administration will look at very carefully before making any approval decisions.

Medicine