Advocates maintain that this process can result in both regression of atherosclerotic plaques and relief of angina and that EDTA reduces oxidative stress in the vascular wall.Anecdotal reports have suggested that EDTA chelation therapy can result in relief of angina in patients with SIHD. Studies in patients with intermittent claudication and SIHD have failed to demonstrate improvements in exercise or digital subtraction angiograms with chelation.40 A randomized controlled trial (RCT) examining the effect of chelation therapy on SIHD studied 84 patients with stable angina and a positive treadmill test for ischemia.41 Those randomized to active therapy received weight-adjusted disodium EDTA chelation therapy for 3 hours per treatment, twice weekly for 15 weeks, and then once monthly for an additional 3 months. There were no differences between groups in changes in exercise time to ischemia, exercise capacity, or quality-of-life scores. The National Center of Complementary and Alternative Medicine and the National Heart, Lung, and Blood Institute conducted TACT (Trial to Assess Chelation an RCT comparing chelation with placebo in patients who had experienced MI. The primary composite endpoint of total mortality, recurrent MI, stroke, coronary revascularization, or hospitalization for angina occurred in 222 (26%) patients in the chelation group and 261 (30%) patients in the placebo group multiple comparisons, statistical significance was considered at p values 0.036]). No individual endpoint differed significantly between groups. Among patients with diabetes mellitus, there in the composite endpoint for the chelation-treated patients relative to the placebo-treated patients (P=0.02 for interaction). 