Patients whose clot-clogged arteries were treated with standard drugs, including aspirin, following serious Heart attack were more likely to maintain opened arteries and live longer if they also took the anti-clotting drug Plavix, researchers said.

Plavix, sold by Sanofi-Aventis and Bristol-Myers Squibb Co., has proven able in earlier trials to help prevent second heart attacks, Strokes and death among patients who had suffered less-serious heart attacks.

“The new trials were meant to show Plavix can also keep the artery open and cut risk of another heart attack in people with large heart attacks, and they did so convincingly,” said Dr. Marc Sabatine, lead researcher of the study sponsored by the two drug makers.

Sabatine’s trial involved nearly 3,500 men and women all of whom were treated within 12 hours of reaching the hospital with severe heart attacks caused by complete blockages of a coronary artery.

“About one third of heart attacks are caused by such complete blockages of a coronary artery,” said Sabatine, a physician at Brigham and Women’s Hospital in Boston.

He presented his findings on Plavix - which has annual sales of more than $5 billion - at the scientific meeting of the American College of Cardiology in Orlando, Fla., on Wednesday. The study will also appear in the New England Journal of Medicine.

All patients received standard drugs, including “clot-busters” such as Genentech Inc.‘s TNKase, as well as two treatments that prevent new clots: aspirin and heparin. Aspirin works by stopping blood cells called platelets from clumping. Heparin works through another mechanism.

Roughly half also receiving daily doses of Plavix, whose chemical name is clopidogrel, while the others got a placebo.

Within about a week after entering the hospital, all patients had been scheduled for an angiogram - an X-Ray of the affected coronary artery - to see if it remained clear after drug treatment.

By the time of their planned angiograms, almost 22 percent of those taking placebo plus standard drug treatment continued to have a clogged artery, died or suffered a second heart attack - compared with only 15 percent in the Plavix group.

“That means that those taking Plavix had a 36 percent reduced chance of these negative outcomes as those taking placebos,” said Sabatine, who has received lecture fees and other remuneration from Sanofi and Bristol-Myers.

Moreover, Sabatine said those taking Plavix had neither overall increased bleeding nor a greater incidence of serious brain hemorrhages, compared with those taking placebos.

“By contrast, other types of potent anti-platelet drugs have been shown in different trials to double the risk of bleeding and brain hemorrhage,” he said.

In a separate editorial in the Journal, doctors Richard Lange and David Hillis concluded that for patients receiving clot-busting therapy a combination of Plavix and aspirin “appears, in fact, to be effective and safe.”

They said Plavix being easier to administer and less expensive than other common treatments, “further adds to its attractiveness” in patients receiving clot-busting therapy.

Favorable results from a large similar Plavix trial conducted in China, called COMMIT, were also presented on Wednesday at the cardiology meeting.

That trial involved 46,000 people who were treated for severe heart attacks within 24 hours with standard drugs, but about half the patients did not have access to expensive clot-busters, Sabatine said.

Patients taking Plavix had significantly fewer incidents of a second hard attack or Stroke within a month of hospitalization, researchers said.

“Plavix is the first drug in 12 years to show a clear survival benefit in patients with big heart attacks, and could therefore become a standard of care for these patients,” Sabatine said.