Results from a sub-study of the Trial to Assess Chelation Therapy (TACT) that focused on quality of life issues in patients who had previously suffered a heart attack and were treated with chelation therapy reveal no improvements in these patients' quality of life.
Late-breaking study results presented at the American Heart Association Scientific Sessions 2012 in Los Angeles, California, revealed that treatment with chelation therapy does not improve the quality of life of patients who have previously suffered a heart attack.
Daniel B. Mark, MD, MPH, lead author of the sub-study of the Trial to Assess Chelation Therapy (TACT), and professor of medicine and director of outcomes research at Duke University Medical Center and Duke Clinical Research Institute, said the objective of the sub-study was to determine whether chelation therapy significantly altered emotional well being and physical functioning capabilities in patients with stable coronary artery disease (CAD).
The TACT study used a chelation infusion regimen that contained disodium ethylene diamine tetra-acetic acid (EDTA), ascorbic acid (vitamin C), B-vitamins, electrolytes, a local anesthetic, and the anti-clotting agent heparin.
Chelation therapy is an effective treatment for heavy metal poisoning that has also been used since the 1950s by some practitioners as a treatment for heart disease (under the theory that chelation therapy can remove calcium from the body and unblock clogged arteries). However, there has been a lack of large-scale controlled clinical trials showing the effectiveness of chelation therapy for treating atherosclerosis and heart disease. Thus, the use of chelation therapy to treat heart disease has been discouraged by many traditional medical professional societies.
However, although this substudy showed that treatment with chelation therapy did not have a profound impact on patients’ quality of life, the larger TACT study did show that chelation decreased the risk of death, second heart attacks, stroke, and the need for additional heart procedures in patients who had previously suffered heart attacks.
For this study, researchers randomly selected 911 (53%) of the 1,709 patients in the main TACT study. Using the Duke Activity Status Index (DASI) and other instruments to measure the patients’ quality of life and competence in completing daily tasks, the researchers conducted interviews at baseline, 6 months, 12 months, and 24 months. Follow up interviews were conducted by telephone by the DCRI Outcomes Group. The study was conducted at 134 sites in the United States and Canada.
A DASI score of 0 means that the patient could not perform any daily tasks that are associated with self care, such as eating, using the restroom, and dressing themselves. The highest score of 48 “would be achieved by a professional athlete,” Mark said. The average DASI score at baseline was 24.6; after 24 months, the average score was 27.1 “We didn’t see any effect on the quality of life of chelation therapy patients,” said Marks. “Patients weren’t any worse, but they weren’t any better.”
Researchers reported similar results when patients were evaluated using the Short Form Health Survey (SF-36), which assesses mental wellbeing and stress. “We thought it might make people feel better, but we didn't see that consistently enough,” Mark said.
Results from the Main TACT Study Greeted with Skepticism
Although results from the larger TACT trial presented at AHA 2012 indicated that treatment with chelation therapy “reduced the risk of heart attacks, deaths, strokes and other cardiovascular problems by 18%” in heart attack patients,” even the lead study author agreed with the chorus of cardiology experts urging extreme caution in interpreting the results.
In the study, more than one-quarter (26%) of patients treated with chelation therapy experienced a cardiovascular event (death, heart attack, stroke, coronary revascularization, or hospitalization for angina), compared with 30% of patients who received placebo, a four percentage-point difference that could be caused by random chance, according to the authors. Adding further cause for concern, 17% of patients dropped out of the study altogether. Others have noted that “nearly all the benefit in the trial was found to occur among the one-third of patients in the trial who had diabetes.”
Questions to Consider:
Do these study results change your current opinion of the clinical utility and safety of chelation therapy in this patient population?
Do you use chelation therapy in your practice with heart attack patients? If so, which factors do you consider during patient selection?
What do you think accounts for the disproportionate number of patients with diabetes who benefited from chelation therapy in this study?