From the AHA;
The American Heart Association has reviewed the available literature on using chelation (ke-LA'shun) (E.D.T.A., ethylenediamine tetraacetic acid) to treat arteriosclerotic (ar-te"re-o-skleh-ROT'ik) heart disease. We found no scientific evidence to demonstrate any benefit from this form of therapy.
Chelation therapy is a recognized treatment for heavy metal (such as lead) poisoning. EDTA, injected into the blood, will bind the metals and allow them to be removed from the body in the urine. Chelation therapy is not approved by the FDA to treat coronary artery disease, but some physicians and alternative medicine practitioners use it for this purpose.
Up to now, there have been no adequate, controlled, published scientific studies using currently approved scientific methodology to support this therapy for cardiovascular disease. The United States Food and Drug Administration (FDA), the National Institutes of Health (NIH) and the American College of Cardiology all agree with the American Heart Association on this point.
Also, from the National Institute of Health;
Am Heart J. 2000 Jul;140(1):139-41.
Chelation therapy for coronary heart disease: An overview of all clinical investigations. Ernst E.
Department of Complementary Medicine, School of Postgraduate Medicine and Health Sciences, University of Exeter, United Kingdom. E.***@****
Comment in:
Am Heart J. 2002 Nov;144(5):E10; author reply E11. Am Heart J. 2000 Jul;140(1):4-5.
BACKGROUND: Chelation therapy is popular in the United States. The question of whether it does more good than harm remains controversial. AIM: The aim of this systematic review was to summarize all the clinical evidence for or against the effectiveness and efficacy of chelation therapy for coronary heart disease. METHODS: A thorough search strategy was implemented to retrieve all clinical investigations regardless of whether they were controlled or uncontrolled. RESULTS: The most striking finding is the almost total lack of convincing evidence for efficacy. Numerous case reports and case series were found. The majority of these publications seem to indicate that chelation therapy is effective. Only 2 controlled clinical trials were located. They provide no evidence that chelation therapy is efficacious beyond a powerful placebo effect. CONCLUSION: Given the potential of chelation therapy to cause severe adverse effects, this treatment should now be considered obsolete.
I do believe it is showing good results at the moment, but as far as I'm aware it is only being reserved for the most serious cases. However, as time progresses I think this will probably change.