OBSTRUCTION OF CORONARY ARTERIES BY cholesterol, calcium deposition, and fibrotic tissue followed by accumulation of blood particles, platelets, and finally thrombosis is the cause for angina, heart attack, heart failure, and sudden death. After more than 50 years of considerable research on the cause and prevention of obstruction to coronary arteries by plaques of atheroma, we are still a moon ride away from preventing obstruction to arteries. Chelation, a method for clearing the obstruction, is analogous to using Drano to clean obstructed pipes. Treatments cost approximately $4000 per year and, surprisingly, during the 1980s and 1990s was used by more than half a million patients in the United States annually. It appears that in Canada approximately 8% of patients undergoing coronary angiography have tried chelation therapy. Controversies have raged in the last 30 years regarding the value of chelation therapy.

CLINICAL STUDY

Study question: Does chelation therapy with EDTA impact exercise-induced ischemia or quality of life in patients with stable coronary artery disease?
Methods: A double-blind randomized clinical trial of 84 patients with stable angina (stable coronary artery disease) on the usual recommended medical therapy and significant electrocardiographic ST segment depression were studied. EDTA 40 mg/kg or placebo was administered for three hours per treatment twice weekly for 15 weeks and then once monthly for three months. Male patients represented 84% of the study group, average age 65 years, multivessel disease was present in approximately 55%, 50% of patients were asymptomatic, and 60% had significant angina.
Results: At baseline there was no difference in the time of onset of ischemia on electrocardiographic treadmill testing. After treatment there was no difference to support a beneficial effect of calcium chelation therapy with EDTA. There was no difference in exercise time to induce ischemia on the treadmill and no difference in exercise capacity or quality of life.

PERSPECTIVE

Knudtson et al. concluded: ‘‘physicians can now inform patients that there is no scientific evidence to support the claim that $4000 per year for chelation therapy with EDTA is money well spent.’’ The fact that controversial chelation therapy is still practiced indicates that we do not have treatment that provides satisfactory beneficial effects for the majority of patients treated for obstructive coronary artery disease and that more research is required. The idea of chelation should not be abandoned. EDTA has had its day but perhaps other molecules that can dissolve plaques of atheroma should be sought.