Stephen J.LurieMD, PhD, Senior EditorIndividualAuthor
To the Editor: Dr Knudtson and colleagues1 reported that chelation therapy with EDTA is no
more effective than placebo in improving exercise time to ischemia, exercise
capacity, and quality of life measurements in patients with ischemic heart
There are several problems with this study. First, the control group
was not treated with a true placebo. Intravenous ascorbic acid (an antioxidant)
and magnesium (an antihypertensive) may both have had beneficial effects.
Second, the authors dismissed the statistically significant improvement from
baseline in exercise time to ischemia in both groups as "consistent with a
combination of placebo and training effects commonly seen in studies of angina
patients." If it takes so little to achieve a statistically significant improvement
perhaps this should not have been used as the primary end point of the study.
Use of a different end point could have allowed the inclusion of more than
650 patients who either could not walk on a treadmill or did not meet the
treadmill test requirements. A more meaningful end point would have been cardiac
events (ie, death, myocardial infarction, angioplasty, or coronary artery
bypass graft surgery).
Strassberg D. Chelation Therapy for Patients With Ischemic Heart Disease. JAMA. 2002;287(16):2077-2078. doi:10.1001/jama.287.16.2073