Nearly a decade ago, the National Institutes of Health began a study to determine whether patients with heart disease could be treated with chelation therapy, a controversial method that has been used by 110,000 Americans each year. However, the authors conclude they still are not sure whether chelation works.

According to the results, published in the Journal of the American Medical Association, chelation did slightly decrease the risk of heart problems, mostly in people with diabetes. However, the benefit was so small that it may have been due to chance.

During the study, chelation therapy, with the drug disodium EDTA used in patients with a prior heart attack, modestly decreased the risk of adverse cardiovascular outcomes. However, the results do not support continuous use of this therapy for treatment of patients who have not suffered a heart attack.

Chelation therapy is an intravenous method of treatment consisting of chelating agents to treat heavy metal toxicity. Because of beneficial anecdotal and documented experience, chelation therapy has recently become a treatment for coronary and peripheral artery disease.

Background information from the article explained:

“Three small clinical trials have assessed the effects of chelation on surrogate outcomes, such as walking distance in patients with claudication and time to exercise-induced ischemia in patients with coronary disease. These studies did not find any evidence of treatment efficacy but were underpowered for evaluation of clinical events.”

Because of this, medical organizations consider the advantage of chelation therapy for therosclerotic vascular disease unproven, and the use of this therapy as possibly harmful.

When used too quickly, disodium EDTA could result in hypocalcemia – low levels of calcium in the blood – or even death. Chelation therapy consisting of disodium EDTA has been used for nearly 50 years as treatment for atherosclerosis – hardening of the arteries.

The researchers conducted the Trial to Assess Chelation Therapy (TACT) to find out whether an EDTA-based chelation regimen decreases cardiovascular events. The randomized trail recruited 1,708 patients aged 50 or over who had suffered a heart attack at least six weeks beforehand.

Participants were randomly assigned to one of three groups:

  • 40 infusions of a 500mL chelation solution
  • placebo and an oral vitamin-mineral regimen
  • oral placebo

During the trial, fifteen percent stopped infusions because of adverse events.

The investigators found that among the 1,708 patients, 26.5% of those randomly assigned to chelation later suffered a heart problem, compared with 30% of those randomly assigned to a placebo. The heart problems they experienced included:

  • any additional heart attacks
  • deaths
  • strokes
  • hospitalizations for chest pain
  • invasive procedures to unclog arteries

The outcomes met the cutoff for statistical significance, but only by 0.001.

Only 65% of participants got all of their scheduled chelation treatments. Generally, less than 3% of patients drop out of a study, but in this one 17% of patients stopped with their treatments.

Due to this crucial missing data, experts say they can’t come to an accurate conclusion.

The authors conclude:

“In stable patients with a history of MI, the use of an intravenous chelation regimen with disodium EDTA, compared with placebo, modestly reduced the risk of a composite of adverse cardiovascular outcomes, many of which were revascularization procedures. These results provide evidence to guide further research but are not sufficient to support the routine use of chelation therapy for treatment of patients who have had an MI.”

A separate study in 2009 revealed that the chelation therapy drug dimercaptosuccinic acid (DMSA) was found to be safe and beneficial to treat autism.

Written by Kelly Fitzgerald