I. Clinical Study
II. Perspective
GLOSSARY
angina chest pain caused by temporary lack of blood to an area of heart muscle cells usually caused by severe obstruction of the artery supplying blood to the segment of cells.
atherosclerosis same as atheroma, raised plaques on the inner wall filled with cholesterol, calcium, and other substances on the inner wall of the arteries that obstruct the lumen and the flow blood; the plaque of atheroma hardens the artery, hence the term atherosclerosis (sclerosis ¼ hardening).
myocardial infarction death of an area of heart muscle due to blockage of a coronary artery by blood clot and atheroma; medical term for a heart attack or coronary thrombosis.
plaque of atheroma same as atherosclerotic, a plaque that juts into the lumen and obstructs the flow of blood in arteries.
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 obstruc¬tion, 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.

• I. CLINICAL STUDY
  Study question: Does chelation therapy with EDTA impact exercise-induced ischemia or quality of life in patients with stable coronary artery disease?
• II. 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.
• BIBLIOGRAPHY
  Knudtson, M. L.,Wyse, K. G., Galbraith, P. D. et al. Chelation therapy for ischemic heart disease. A randomized controlled trial. JAMA, 287:481–6, 2002.