NIH funds $30-million study of chelation therapy

Bethesda, MD - The National Institutes of Health has announced $30 million in funding to support a randomized trial of chelation therapy for the treatment of CAD. The hope is to provide final proof, one way or the other, of whether this widely used and controversial therapy really works. The trial, called the Trial To Assess Chelation Therapy (TACT), is supported jointly by the National Center for Complementary and Alternative Medicine (NCCAM) and the National Heart, Lung, and Blood Institute (NHLBI) and is set to begin in March of 2003.

"The public health imperative to undertake a definitive study of chelation therapy is clear," Dr Stephen E Strauss, director of NCCAM said in an NIH press statement. "The widespread use of chelation therapy in lieu of established therapies, the lack of adequate prior research to verify its safety and effectiveness, and the overall impact of coronary artery disease convinced NIH that the time is right to launch this rigorous study," he adds.

The release notes that in 1997, more than 800,000 patient visits were made for chelation therapy.

Dr Gervasio A Lamas (Mount Sinai Medical Center-Miami Heart Institute, Miami Beach, FL) will serve as principal investigator for the trial.

Chelation therapy has been used since 1955 for the treatment of CAD. Agents such as ethylenediaminetetraacetic acid (EDTA), which bind metals and are approved by the FDA to treat heavy metal poisoning, are given intravenously to decalcify atherosclerotic plaque. Proponents of the therapy, led by the American College for Advancement in Medicine (ACAM), which has issued a protocol for chelation therapy, reason this therapy may alter plaque morphology and volume or improve endothelial function. However, opponents point to a lack of vigorous investigation of both its safety and efficacy.

Current American Heart Association guidelines on chelation therapy say "there have been no adequate, controlled published scientific studies using currently approved scientific methodology to support this therapy for coronary heart disease. Using this form of unproven treatment for coronary heart disease may deprive patients of the well-established benefits from the many other valuable methods of treating these diseases."

Earlier this year, results of 1 randomized trial, called the Program to Assess Alternative Treatment Strategies to Achieve Cardiac Health (PATCH) trial, were published in the Journal of the American Medical Association and reported at that time by heartwire . In that study, 84 patients with established CAD were randomized to receive EDTA by the ACAM protocol or a placebo infusion.

Time to ischemia, the primary end point, improved significantly compared with baseline in both groups, by 54 seconds in the placebo group, and 63 seconds in the EDTA (p<0.001 for both comparisons with baseline). However, there was no statistically significant difference between the groups. Exercise-capacity and quality-of-life scores showed a similar pattern of improvement in both groups. Such improvement in both groups, the researchers wrote, "is consistent with a combination of placebo and training effects commonly seen in studies of angina patients."

"According to our findings, the use of chelation therapy to increase ischemic thresholds and improve quality of life cannot be supported for patients with ischemic heart disease," the PATCH researchers, with first author Dr Merril L Knudtson (University of Calgary, AB), concluded. "Larger trials with a broader range of patients will be needed to assess the safety and impact of EDTA therapy on clinical event rates."

The new study will enroll 2372 patients, aged 50 or older, who have had a previous MI. They will be randomized to either active chelation therapy with EDTA using the ACAM protocol or placebo. Subjects will also receive vitamin and mineral supplements as recommended in the protocol but will be randomized in a factorial fashion to high- versus low-dose vitamin and mineral supplements.

Participants will receive 30 weekly infusions, followed by 10 bimonthly infusions; the primary end point of the study is a composite of MI, stroke, hospitalization for angina, coronary revascularization, and death. The study will also evaluate cardiac deaths, nonfatal MI, health-related quality of life, and cost effectiveness, among other factors, the release notes.

Recruitment is expected to begin in March 2003. The 5-year study will involve more than 100 sites.

"NCCAM's leadership in initiating and supporting this study is to be commended," NHLBI Director Dr Claude Lenfant notes in the release. "Only a large clinical trial can definitively answer the question of whether chelation treatment is truly safe and effective."

Heartwire from Medscape © 2002 

Cite this: NIH funds $30-million study of chelation therapy - Medscape - Aug 12, 2002.