U.S. researchers have discovered a method of clearing clogged arteries that could revolutionize treatment of the dangerous condition.

They have used a synthetic version of an altered form of HDL cholesterol to clear blockages in artery stems.

HDL (high density lipoprotein) is considered the "good" cholesterol that removes plaque from the bloodstream. The "bad" cholesterol, or LDL (low density lipoprotein), contributes to plaque formation that can clog arteries and lead to heart attacks.

The altered form of HDL was first found 25 years ago in a northern Italian village where people were healthy, despite high levels of LDL cholesterol.

Scientists believed the villagers had a genetic mutation that gave them HDL particles that are larger than normal and more efficient at removing plaque.

The experiment involved a synthetic version of the villagers' HDL.

Esperion Therapeutics Inc., the biotechnology company in Ann Arbor, Mich., that makes the product, funded the study. The findings appeared in Wednesday's issue of the Journal of the American Medical Association.

HDL test subjects improved

The experiment involved 47 patients who had suffered heart attacks or severe chest pain. Thirty-six of them were given infusions of the altered HDL cholesterol for five weeks. Eleven others were given placebos.

After six weeks, patients treated with the HDL showed a four per cent reduction in coronary plaque buildup. Patients in the placebo group showed no significant change in condition.

Most existing drug treatments for high cholesterol target LDL levels and try to reduce them. The new research opens the possibility of a treatment that raises HDL levels.

Researchers said the initial results are promising but further study is required before the therapy can be commercialized.