Orlando, FL - A placebo-controlled study of chelation therapy in people with stable coronary artery disease (CAD) has found no benefits from the alternative medical therapy, according to a late-breaking study presented here at the American College of Cardiology 50th Annual Scientific Session.

"Our research shows that there was no significant difference in treadmill performance and quality of life between the patients who were given a placebo and people who were given the chelation therapy," researcher Dr George Wyse (University of Calgary, Calgary, AB) told delegates.

The belief that chelation, a recognized treatment for heavy metal poisoning, could be used as a treatment for CAD has been around for almost half a century. Advocates for the treatment, represented by the American College for Advancement in Medicine (ACAM), claim that since ethylene diamine tetra-acetic (EDTA) acid binds to metals allowing them to be secreted in the urine, the chemical may also be able to "soften" the arteries by removing plaque and calcium deposits in the coronary vasculature. An AHA statement, supported by the FDA, NIH, and ACC, asserts that there are no adequate, controlled, published scientific studies using currently approved scientific methodology to support chelation therapy for coronary heart disease.

No elation for chelation

Wyse presented the results of the Program to assess Alternative Treatment strategies to achieve Cardiac Health (PATCH) trial, a 6-month follow-up study looking at exercise test outcomes in 84 stable angina patients randomized to receive either EDTA treatment or placebo. Patients were eligible to participate in the trial if they were over the age of 21, had proven CAD, stable angina pectoris, and > 1 mm ST-segment depression within 2-14 minutes on a gradually ramping treadmill test.

Primary endpoint of the study was change in time to 1 mm ST-segment depression at 6 months. Secondary endpoints were other measures of exercise capacity and quality of life changes.

A total of 39 patients each were ultimately randomized to the treatment group, receiving 40 mg/kg up to a maximum of 3 g, or placebo. Both were administered in an IV saline solution over a 3-hour period, 2 times per week over 15 weeks, then once per month for 3 months, for a total of 33 treatments. All patients were given oral multivitamins, which is standard in chelation treatment.

Wyse and colleagues found no significant differences between the treatment groups. There were no deaths, no MIs, 9 hospitalizations for worsening angina with 6 in the chelation group and 3 in the placebo group. Both groups were able to increase their exercise times to approximately 1 minute, an improvement that Wyse attributes to placebo or "training" effect.

Bigger studies warranted

"On the basis of our findings," Wyse concluded, "there is no evidence to support a beneficial effect of chelation therapy in coronary artery disease." He conceded that he didn't believe that the PATCH study could "definitively answer the question," and was only really powered to find something truly "catastrophic." An NIH-funded study is being considered under the joint steering of the NHLBI and the National Center for Complementary and Alternative Medicine (NCCAM).

In a media briefing, Dr Robert Vogel (University of Maryland, Baltimore, MD) emphasized that the real "danger" posed by chelation therapy is that "people would undertake this therapy and forgo proven cardiovascular interventions." A large-scale trial proving or refuting chelation could potentially prevent many unnecessary coronary events. Wyse estimates that there are "thousands" of US physicians offering chelation treatment out of their private practices.

Wyse told heartwire that he hopes the PATCH study can serve as "useful pilot data" but that he himself has no intention of conducting a larger trial. Asked whether his recommendations to patients would change on the basis of his findings he said: "My advice to patients has not changed. It has always been that there is no evidence that chelation has any benefits; there are some potential risks and if you chose to use this therapy you should realize this. The statement that there are no proven benefits still stands."

Shelley Wood shelley@conceptis.com

For a full listing of HeartWire articles please go to theheart.org. HeartWire is the news service of theheart.org. Copyright HeartWire 2001. All rights reserved. Republication or redistribution of HeartWire content is prohibited without prior written consent.

				2001 theheart.org info@theheart.org