ORLANDO, Fla. (AP) - Treating the bloodstream with chelation therapy fails to relieve heart disease, according to the first careful test of this widely used form of alternative medicine.

Although precise numbers are scarce, doctors say millions of dollars are spent in the United States each year on this therapy, which is intended to relieve chest pain.

The treatment is administered by doctors but is generally not covered by insurance and has not been subjected to the kind of rigorous testing required of most drugs. Doctors from the University of Calgary, working with chelation advocates, set out to study the approach in a rigorously controlled six-month experiment.

``We saw no benefit from chelation therapy,'' said Dr. D. George Wyse, who presented the results Wednesday in Orlando at a meeting of the American College of Cardiology.

Chelation therapy involves administering the manmade amino acid EDTA - ethylenediamine tetraacetic acid - into the veins. It is ordinarily used to treat mercury or lead poisoning, because EDTA latches onto heavy metals so they can be excreted in the urine.

In heart disease, proponents say the treatment probably works by reducing the damaging effects of oxygen and perhaps by removing calcium from the buildups that clog the arteries. Supposedly this causes the buildups to break up and disappear.

A single treatment takes about two hours and typically costs $75 to $110. Often 25 to 40 treatments are given, and usually patients must pay the bills. Because advocates in Canada argued the treatment should be covered by insurance, the Alberta government sponsored Wyse's study to test its worth.

Wyse said he designed the study with advice from members of the American College for Advancement in Medicine, an alternative medicine organization. In all, 84 heart patients were randomly assigned to get chelation or dummy injections.

They got two treatments a week for 15 weeks, followed by monthly treatments for three months. After six months, Wyse said, ``there was absolutely no difference between the two groups.''

Both those who got the treatment and those who did not were able to increase their walking time on a treadmill by an average of one minute.

``My advice to patients is not changed,'' Wyse said. ``There is no evidence that it works.''

Dr. Michael Janson of Arlington, Mass., past president of the American College for Advancement in Medicine, questioned whether the study included enough patients.

``I've been doing it for 18 years and have seen some dramatic differences,'' he said. ``I've been really impressed with it.''

He said three-quarters of his patients respond and are able to walk farther and have less chest pain.

The American Heart Association and several other medical organizations are skeptical about chelation.

``We now have some concrete information that should help patients decide how to spend their health care dollars,'' said Dr. Rose Marie Robertson of Vanderbilt University, the heart association's president.

Dr. Robert Vogel of the University of Maryland said chelation can actually be harmful if patients choose it over proven treatments and lifestyle changes.

Janson estimated that 2,500 doctors in the United States offer chelation therapy.

Copyright 2001 The Associated Press. All rights reserved.