Chelation Therapy Is TACT-less

G. Jackson


Int J Clin Pract. 2008;62(12):1821-1822. 

The 2007 Chronic Angina American Heart Association/American College of Cardiology Guidelines for the management of stable angina concluded[1]:

"Chelation therapy (intravenous infusions of ethylenediamine tetra-acetic acid or EDTA) is not recommended for the treatment of chronic angina or arteriosclerotic cardiovascular disease and may be harmful because of its potential to cause hypocalcaemia."

So one wonders why it is still widely used, given the lack of evidence of benefit and the potential to do harm (financial gain seems the most likely reason). It is even more surprising to learn of the Trial to Assess Chelation Therapy (TACT), a 5-year National Institutes of Health (NIH) funded (30 million dollars) clinical study. TACT is a randomised double-blind placebo-controlled study designed to evaluate the efficacy of EDTA chelation therapy for the treatment of coronary artery disease. Patients aged 50 years or older with a documented myocardial infarction are randomly allocated 40 infusions of EDTA or placebo. Or rather they were allocated, because recruitment has been suspended for reasons that are not at all clear - issues have arisen regarding the consent form and impropriety.

The primary end-point of the TACT trial is the usual cardiac composite of myocardial infarction, stroke, hospitalisation for angina and/or heart failure and overall mortality. To date, 1500 patients out of the target 2000 have been entered into the study. A comprehensive review of the TACT trial by Atwood et al.[2] calls into question the safety of the study and highlights deficiencies in the NIH application process, economy with detailing the adverse effect potential, inappropriate political pressure to undertake the study and failure to provide complete data on conflicts of interest, especially investigator financial gain. The authors concluded in May 2008:

"... TACT is unethical, dangerous, pointless and wasteful. It should be abandoned."

One wonders where everyone has been in the 5 months it took to suspend recruitment.

The TACT trial principal investigator justified the study in the British Journal of Cardiology[3] - an odd vehicle for an NIH study. However, Atwood et al. point out many inaccuracies in the editorial which misrepresents the information available. The approval of the TACT trial appears to have involved 'data massage', particularly as one of the articles cited to justify TACT was written by a chelationist who admitted under oath fabricating his data (he is cited over five times in the TACT protocol).

As a result of chelationists' claims, randomised-controlled trials involving 300 patients and performed by non-chelationists (academics) found no evidence of benefit comparing EDTA with placebo.[2,3] These findings were rejected by chelationists - after all, 66,000 patients a year in the USA alone receive 40-50 infusions of EDTA at up to $5000 a course, so why bother with science?.[3] Well, it could be argued TACT is an attempt to address the scientific concerns and is therefore justified, however, there are no laboratory, animal or human phase 1 or 2 studies and the trial fails to conform to the Declaration of Helsinki mandatory guidelines, so is not publishable in a reputable scientific journal, although I am sure it will find its way into the media (providing there is no downside).

A lot of questions need to be asked about TACT, not least the role of the American College of Advanced Medicine which promotes alternative medical therapies, the National Centre for Complementary and Alternative Medicine and the political interference. The trial is based on exaggerated claims from case reports and inadequate concern about adverse effects. How the NIH came to throw away £30 million also needs explaining.

The British Journal of Cardiology editorial finishes with: 'The results of TACT will provide either a significant positive result or an informative negative result upon which clinical decision-making and health policy can be based'. That would be true if the co-investigators were of adequate scientific ability, risks were clearly explained in the consent form, and appropriate precautions were in place to minimise the risk. There is no evidence that this is the case. Atwood et al. do science a service in their review and perhaps we need reminding of the dictionary definitions:

TACT -'intuitive perception of the right thing to do or say'.
TACTless -'having or showing no tact'.

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