Los Angeles—Most cardiologists listening to late-breaking findings of a clinical trial presented here at the annual Scientific Sessions of the American Heart Association (AHA) likely expected to hear that chelation therapy does not help prevent future cardiovascular problems in patients who previously experienced a heart attack. Instead, researchers reported the surprising finding that the treatment did improve outcomes, although the effect did not appear to be large.
The randomized, placebo-controlled trial found that in patients who had previously had a heart attack, chelation therapy resulted in fewer cardiovascular events, defined as death, heart attack, stroke, coronary revascularization, and hospitalization for angina. But the difference between the 2 groups barely reached significance: 26% of those given chelation therapy experienced such an event compared with 30% for patients randomized to receive a placebo.
Chelation therapy, typically used to remove heavy metals such as lead or iron from the body, has been around for more than 50 years. Calcium ethylene diamine tetra-acetic (EDTA) is approved for treating lead poisoning, and other chelation drugs are used for treating iron overload following repeated blood transfusions. Some physicians who use complementary and alternative therapies have argued chelation therapy is effective in treating patients with atherosclerosis. In the new study, funded by the National Center for Complementary and Alternative Medicine and the National Heart, Lung, and Blood Institute, the investigators hypothesized that a chelating agent would improve vascular function and reduce inflammation and cardiovascular disease events by reducing oxidative stress in the vascular wall.
Although chelation therapy for patients with heart disease has been considered controversial and there have been no large, long-term clinical trials to determine if it might offer a benefit to patients with coronary artery disease, an estimated 100 000 patients in the United States receive off-label chelation therapy.
In the study, the Trial to Assess Chelation Therapy, or TACT, 1708 patients were enrolled at 134 sites between 2003 and 2010; the participants were randomized to receive 40 infusions of a 500-mL chelation solution with multivitamin and mineral supplements or a placebo infusion with supplements and were then followed up for a median of 4 years. Patients with diabetes had the most benefit (67 events among those given chelation therapy compared with 102 events among those receiving placebo), experiencing a 39% reduction in risk of a cardiovascular event compared with no reduction of cardiovascular events in those receiving placebo.
Gervasio A. (Tony) Lamas, MD, of Mount Sinai Medical Center in Miami Beach, Fla, and lead author, cautioned the audience that his team’s findings would require further confirmation before chelation therapy could be adopted as part of standard practice.
“Intriguing as the results are, they are unexpected and should not be interpreted as an indication to adopt chelation therapy into practice,” said Elliott Antman, MD, AHA’s chair of the Scientific Sessions Program Committee in a statement. “More information is needed about which elements of the complex infusion mixture might provide benefit, the marked differences between the observed treatment effect in diabetics versus nondiabetics needs to be understood, and we need to be sure that the findings can be replicated.”