Adding the blood thinner Plavix (search) to standard heart attack treatments could cut deaths from severe heart attacks by more than a third.

“There will be about a million heart attacks in the U.S. this year and about a third of them will be this type of severe heart attack; that’s about more than 300,000 heart attacks,” says researcher Marc S. Sabatine, MD, MPH, of Harvard Medical School.

Doctors refer to these severe heart attacks with the term “ST-elevation (search)” due to specific changes that are seen on a heart monitor. These heart attacks occur when blood flow to the heart is severely reduced.

Severe heart attack treatment usually includes clot busting drugs and aspirin. But Harvard researchers say adding Plavix, a potent blood thinner (search), cuts deaths and second heart attacks by 36 percent compared with standard heart attack treatment.

In the study, patients who took Plavix as part of their heart attack treatment were also 20 percent less likely to need heart bypass surgery. The study was funded by Plavix makers Sanofi-Aventis and Bristol-Myers Squibb.

Sabatine says Plavix, which is already standard treatment for people who have blocked arteries opened by steel mesh tubes called stents, works with aspirin to keep blood clots from forming in blood vessels. “It keeps the vessels open,” he says.

'Good Treatment for Heart Attack'

“This is a major finding,” Robert Bonow, MD, chief of cardiology at Northwestern University's Feinberg School of Medicine, tells WebMD. “This is likely to have a major impact.”

Christopher P. Cannon, MD, associate professor of medicine at Harvard Medical School and a co-researcher of the study, tells WebMD that “we are 99.99 percent sure that this is a good treatment for heart attack.”

Sidney Smith, MD, director of the Center for Cardiovascular Science and Medicine at the University of North Carolina in Chapel Hill, tells WebMD that the findings are “the missing link.”

"We knew that Plavix worked in mild heart attacks, but we were waiting to see if it would work the same in [more severe heart attacks] -- and it does," he says.

Sabatine tells WebMD that the best way to open a completely blocked artery is to immediately perform a balloon angioplasty. That approach is only available in about 25 percent to 30 percent of U.S. hospitals. “So most heart attacks are treated with medical therapy,” he says.

Results of the 3,500-patient study were reported at the American College of Cardiology 2005 Scientific Sessions. The study was also published online by The New England Journal of Medicine.

In the study, about half the patients were given clot busting treatment plus aspirin and Plavix. The other half received clot busters, aspirin, and a placebo. Patients who took Plavix were initially given 300 mg of Plavix, followed by 75 mg daily for eight days or hospital discharge, whichever came first.

Because Plavix is a potent blood thinner, there was some concern that giving aspirin and Plavix together could increase risk of serious bleeding -- including bleeding in the brain.

Sabatine says, however, that major bleeding did not occur any more frequently in the patients taking Plavix.

By Peggy Peck, reviewed by Michael W. Smith, MD

SOURCE: American College of Cardiology 2005 Scientific Session, Orlando, Fla., March 6-9, 2005. The New England Journal of Medicine, 2005; vol 352. Marc S. Sabatine, MD, MPH, Harvard Medical School, Boston. Robert Bonow, MD, Feinberg School of Medicine, Northwestern University, Chicago. Christopher P. Cannon, MD, associate professor of medicine, Harvard Medical School, Boston. Sidney Smith MD, University of North Carolina, Chapel Hill.