A major clinical investigation has found that a 99-year-old blood thinner works just as well during the placement of artery-opening stents as a newer drug that costs 400 times more.

Many doctors in recent years have chosen the expensive anti-clotting agent Angiomax over low-cost heparin for coronary angioplasty -- believing the newer medication is safer.

Angioplasty, performed about 500,000 times annually in the United States, involves threading a flexible catheter through a vessel in the leg or wrist to reach a blocked main heart artery. The procedure is vital for the placement of stents -- small meshlike tubes -- that are deployed in obstructed arteries. A blood thinner is needed to prevent potentially deadly clotting while patients are undergoing the procedure.

But Angiomax has no obvious safety benefits over low-dose heparin and may not be worth the cost, said Dr. Peter Berger, senior vice president for clinical research with the North Shore-LIJ Health System.

In an editorial in last week's New England Journal of Medicine, Berger assessed a massive head-to-head clinical trial in Europe of Angiomax versus heparin. The investigation, dubbed Matrix, tested the two thinners in more than 7,000 patients.

"Heparin costs a few dollars per dose," Berger said. "Angiomax costs more than $800 per dose although hospitals can negotiate the price down and join buyers' clubs. But that's still a 400-fold difference in price."

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When doctors use lower doses the evidence is clear, he said, that heparin prevents clotting and doesn't cause excessive bleeding.

Heparin has a long and storied past and was first isolated in 1916 at Johns Hopkins University. The substance is not a synthetic but a natural compound made by the body's own basophils and mast cells, two populations of white blood cells involved in inflammatory reactions.

Dr. Efthymios Deliargyris, vice president for acute cardiovascular care at The Medicines Co. in Parsippany, New Jersey, which manufactures Angiomax, said the latest clinical trial proved that Angiomax is an effective medication.

Even though it is dramatically more expensive, Deliargyris said the medication had aided countless patients during angioplasty.

"The drug performed exactly as expected," he said. Moreover, clinical trial results followed an old principle of pharmacology: When a drug is given appropriately, it will perform exactly as expected, Deliargyris said.

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The Medicines Co. develops drugs for acute cardiovascular care, severe and often drug-resistant infectious diseases, and acute surgical care.

However, inherent in the new research is not only the cost but old versus new, an issue that continues to surface in many areas of medicine.

Last year, scientists at the University of Michigan and two other institutions drew an even sharper contrast when weighing older diabetes medications against two newer classes.

Based on computer modeling and 15 years' worth of data from more than 37,000 patients, the researchers found that newer diabetes drugs cost dramatically more but offered no better benefits -- not even longer life.

"Conventional wisdom would suggest the newer medications should be more effective since they cost more," principal investigator Brian Denton said. But the major difference that he and his colleagues discerned was cost.

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In the heparin versus Angiomax research, Berger said even though previous studies had shown the newer drug to be safer, other investigations proved heparin to be equally safe, especially at lower doses. "If the more expensive blood thinner is not safer or better in some way, the less expensive one ought to be used," he said.