Objectives

To separately determine if (1) ethylene diamine tetra-acetic (EDTA) chelation therapy and (2) oral multivitamins are safe and effective in reducing cardiovascular events in individuals with a history of myocardial infarction (MI).

Background

Coronary heart disease is a leading cause of death among men and women in the United States. In addition to following the standard medical advice of incorporating healthy lifestyle choices such as a heart healthy diet, regular exercise, and smoking cessation, patients may receive chelation therapy as a means to reduce cardiovascular plaque and the complications associated with it.

Historically, chelation therapy involves injecting EDTA into the bloodstream where it binds to toxic agents such as heavy metals and/or minerals, and eliminates them from the body via urinary excretion. Built on this premise, it was believed that chelation therapy could reduce calcium buildup, a mineral and primary contributor to the formation of vascular plaque. Although, chelation therapy with disodium EDTA has been used in the treatment of atherosclerotic disease for more than 50 years, there have not been controlled trials to support or refute its efficacy for improving clinical outcomes. Therefore patients are exposed to uncertain risks for unproven benefits. In addition, The FDA removed edetate disodium from the market in 2008, after the initiation of the TACT trial.

As another approach, diets rich in a mix of antioxidants and other micronutrients are associated with lower rates of atherosclerosis. However, clinical trials have not been able to replicate the benefits and have assessed only a small number of the vitamins and minerals present in multivitamin and multimineral supplements.

Participants

1708 participants were enrolled in the TACT study. Participants were eligible if they were 50 years or older and had a myocardial infarction at least 6 weeks prior to the start of the study. Exclusion criteria included serum creatinine levels greater than 2.0 mg/dL, a platelet count lower than 100,000/mm3, blood pressure measurements greater than 160/100 mmHg, history of liver disease, chelation therapy within five years, and coronary or carotid revascularization procedure within six months.

Design

TACT was a double-blind, placebo-controlled, 2 × 2 factorial trial where patients were randomized to receive either intravenous disodium EDTA chelation therapy or a placebo transfusion, and additionally a high dose oral vitamin and mineral regimen or an oral placebo. 421 participants were assigned to the EDTA and high dose vitamin arm, 418 to the EDTA and vitamin placebo arm, 432 to the EDTA placebo and high dose vitamin arm, and 437 to the EDTA placebo and vitamin placebo arm. A total of 289 participants withdrew consent during the course of the trial.

Chelation therapy consisted of 40 infusions of a 500 mL chelation solution consisting of: 3 grams of disodium EDTA, 7 grams of ascorbic acid, 2 grams of magnesium chloride, 100 mg of procaine HCl, 2500 U of unfractionated heparin, 2 mEq potassium chloride, 840 mg sodium bicarbonate, 250 mg pantothenic acid, 100 mg thiamine, 100 mg pyridoxine, and sterile water. The first 30 Infusions were to be administered weekly, then an additional 10 infusions were to be administered 2 to 8 weeks apart. All participants, regardless of therapy or placebo group, were to receive a daily low dose multivitamin during the infusion stage of the trial to prevent potential depletion by the chelation regimen. Following the infusion phase, patients were to be called quarterly; attend annual clinic visits; and seen at the end of the trial or at the 5 year follow-up, whichever came first.

The active high-dose vitamin treatment was a 28-component mixture to be taken as 3 caplets twice daily, throughout the duration of the trial. This was designed to reflect the vitamin regimen commonly used by chelation practitioners.

The primary study outcome was a composite of mortality from any cause, recurrent MI, stroke, coronary revascularization, or hospitalization for angina measured over a five year follow-up period.

Conclusions

Reduction of mortality was not statistically significant for patients receiving chelation therapy but it was noted that the trial had low statistical power for this evaluation. Chelation therapy for stable patients with a history of MI showed modest improvement in the reduction of non-fatal cardiovascular events but the results were not significant enough to recommend its routine use and further research may be warranted.

High-dose oral multivitamins and multiminerals did not produce a statistically significant reduction in cardiovascular events in patients with a history of MI. The results were limited by the relatively high rate of participant non-compliance.

Lamas GA, Goertz C, Boineau R, et al. Effect of disodium EDTA chelation regimen on cardiovascular events in patients with previous myocardial infarction: The TACT Randomized Trial. JAMA : the journal of the American Medical Association. 2013;309(12):1241-1250. doi:10.1001/jama.2013.2107.

Lamas GA, Boineau R, Goertz C, et al. Oral High-Dose Multivitamins and Minerals or Post Myocardial Infarction Patients in TACT. Annals of internal medicine. 2013;159(12):797-805.

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