Context: Chelation therapy using EDTA is an unproven but widely used alternative therapy for ischemic heart disease.
Objective: To determine if current EDTA protocols have a favorable impact on exercise ischemia threshold and quality of life measures in patients with stable ischemic heart disease.
Design: Double-blind, randomized, placebo-controlled trial conducted between January 1996 and January 2000.
Setting: Participants were recruited from a cohort of cardiac catheterization patients and the practices of cardiologists in Calgary, Alberta.
Participants: We screened 3140 patients, performed a qualifying treadmill test in 171, and enrolled 84. Entry criteria included age at least 21 years with coronary artery disease proven by angiography or a documented myocardial infarction and stable angina while receiving optimal medical therapy. The required treadmill test used a gradual ramping protocol and patients had to demonstrate at least 1-mm ST depression.
Interventions: Patients were randomly assigned to receive infusion with either weight-adjusted (40 mg/kg) EDTA chelation therapy (n = 41) or placebo (n = 43) for 3 hours per treatment, twice weekly for 15 weeks and once per month for an additional 3 months. Patients in both groups took oral multivitamin therapy as well.
Main outcome measure: Change from baseline to 27-week follow-up in time to ischemia (1-mm ST depression).
Results: Thirty-nine patients in each group completed the 27-week protocol. One chelation patient had therapy discontinued for a transient rise in serum creatinine. The mean (SD) baseline exercise time to ischemia was 572 (172) and 589 (176) seconds in the placebo and chelation groups, respectively. The corresponding mean changes in time to ischemia at 27 weeks were 54 seconds (95% confidence interval [CI], 23-84 seconds; P<.001) and 63 seconds (95% CI, 29-95 seconds; P<.001), for a difference of 9 seconds (95% CI, -36 to 53 seconds; P =.69). Exercise capacity and quality of life scores improved by similar degrees in both groups.
Conclusion: Based on exercise time to ischemia, exercise capacity, and quality of life measurements, there is no evidence to support a beneficial effect of chelation therapy in patients with ischemic heart disease, stable angina, and a positive treadmill test for ischemia.