New Blood Thinner Promising

Nov. 5, 2007 (Orlando, Fla.) -- A new, more potent blood thinner works better than Plavix, the current standard treatment, at preventing heart attacks, strokes, and deaths from heart disease in people who undergo procedures to open up clogged coronary arteries, a study of more than 13,000 people shows.

But the new drug, prasugrel, also appears to raise the risk of life-threatening bleeding, particularly in people who have had a previous stroke, are elderly, or who have a low body weight.

Nevertheless, the benefits outweigh the risks for most people, says study head Elliott Antman, MD, a professor of medicine at Harvard Medical School and director of the Samuel A. Levine Cardiac Unit at Brigham and Women's Hospital in Boston.

For every 1,000 people treated with prasugrel as compared with Plavix, the new drug prevented 23 heart attacks and caused six major bleeds, Antman tells WebMD.

The findings, which were presented at the annual meeting of the American Heart Association (AHA), were simultaneously published online by The New England Journal of Medicine.

Blood Thinners Prevent Clotting

Due to an increased risk of blood clots, people who get stents -- tiny, mesh-like tubular structures that prop open clogged arteries after angioplasty -- are typically given blood-thinning treatment with a combination of Plavix and aspirin.

Plavix and prasugrel are both antiplatelet drugs. They block platelets, which are a component of blood, from clumping together into clots that can lead to a heart attack or stroke.

But too much of a good thing can turn nasty. If the drugs go too far at inhibiting platelets, bleeding can occur.

New Blood Thinner Prevents Heart Problems

The study involved 13,608 patients from 30 countries who were undergoing angioplasty and stenting due to heart attacks or serious heart-related chest pain. They were randomly assigned to take Plavix or prasugrel for an average of 12 months.

"We hypothesized that a regimen that ... inhibits the ability of platelets to clot more effectively would reduce events in patients undergoing [angioplasty]," Antman says. "It did."

Among the findings:

• Twelve percent of people taking Plavix suffered a heart attack or stroke or died of heart disease, compared with 10% of those on prasugrel, a 19% reduction in risk.
• Only 1% of people on the new drug developed clogged stents vs. 2.4% on Plavix, corresponding to a 52% reduction in risk.
• Nearly 10% of people given Plavix had a heart attack vs. 7% on prasugrel, a 24% reduction in risk.
• Major bleeding occurred in 2.4% of those on prasugrel, compared with 1.8% of those on Plavix. Fatal bleeding was uncommon, but four times more frequent with the new drug: 0.4% vs. 0.1% of people on Plavix.
• The risk of dying from any cause, 3%, was similar in both groups.