The Trial to Assess Chelation Therapy (TACT), a massive NIH-sponsored study, has reached roughly 75% of its recruitment target of 2,372 heart disease patients. The trial leaders are actively seeking more clinical sites and more patients to complete enrollment.
The $30 million five-year study, overseen by the National Heart, Lung and Blood Institute, and headed by Dr. Gervasio Lamas, MD, director of cardiovascular research at Mount Sinai Medical Center, Miami Beach, FL, will go a long way in answering the long-debated question of whether chelation has a place in the management of atherosclerosis and prevention of myocardial infarction.
Chelation via intravenous infusion of substances like ethylene diamine tetra-acetic acid (EDTA) is FDA-approved for treatment of lead poisoning and other acute heavy metal toxicities, but it is not approved in the heart disease context. It is not generally accepted by mainstream cardiologists, though it has long been a mainstay in many alternative, preventive and “anti-aging” clinics.
Despite the controversy, it is increasingly popular with patients. Advocates believe it can markedly reduce risk of cardiac events by helping to dissolve atherosclerotic plaques in the coronary arteries.
Several hypotheses have been forwarded to explain how chelation might work. One suggests that EDTA decalcifies the plaques, making them easier to resorb; another proposes that EDTA acts indirectly by stimulating release of a hormone that causes calcium to be removed from the plaques. A third theory centers on antioxidant effects of EDTA in the vessel walls.
None of these hypotheses have been tested in clinical studies. In fact, there is little data so far that documents therapeutic effects from chelation in treatment of heart disease. Two systematic reviews of the available small studies, one from the Cochrane Collaboration and another from the Canadian College of Naturopathic Medicine both concluded that available evidence is insufficient to support wide use of chelation for heart disease (Seely DM, et al. BMC Cardiovasc Disord. 2005; 5(32); Villaruz MV, et al. Cochrane Database Syst Rev. 2002; (4): CD002785).
Still, with the recent studies showing that drug-eleuting stents may actually increase rather than decrease subsequent cardiac events, patient and physician interest in alternatives like chelation is on the rise. An article by LT Chappell in the Alternative Medicine Review last June suggests that EDTA chelation may actually outperform clopidogrel-eleuting stents in reducing thrombosis (Chappell LT. Altern Med Rev. 2007; 12(2): 152–158).
All of this makes TACT very timely. The study randomizes 2,372 people over age 50 who have had a myocardial infarction in the past 6 weeks, to 40 infusions of either EDTA, the most commonly used chelating agent, or a placebo solution. Patients in each study arm are further randomized to receive high or low-dose vitamin-mineral supplements. Nutritional supplementation is an essential part of chelation in most clinics, and it will be interesting to see what proportion of any observed therapeutic effect would be attributable to the actual chelation, and what would be attributable to the supplements.
Investigators will follow patients for 5 years, the primary endpoint being a composite of all cause mortality, myocardial infarction, stroke, hospitalization for angina, and hospitalization for congestive heart failure.
TACT has been a long time coming. It was originally planned in 2002 and launched in 2003, under the enthusiastic aegis of Dr. Stephen Straus, the recently deceased head of the National Centers for Complementary and Alternative Medicine (NCCAM). But the study quickly foundered in the choppy waters of inter-institute politics, funding-controversies and oversight disputes.
With fresh support from NHLBI, the trial is now in full swing, and set to be completed in the summer of 2009. There are currently 163 sites involved in the study; 7 of the 10 largest sites are Complementary and Alternative Medicine (CAM) centers at major universities or medical centers.
“It has not been easy,” said Kenny Bock, MD, immediate past president of the American College for the Advancement of Medicine, speaking of the turbulent history of TACT. ACAM has historically included many chelation practitioners among its members, and the organization has an understandably strong interest in the outcome of the study. TACT is, “a very big deal and really deserves our support,” Dr. Bock said in an address at the ACAM Fall conference.
However the data turn out, the study is a milestone in the evolution of large-scale clinical research at CAM centers, said Dr. Bock.
For more information or to participate in the trial contact the TACT research team at 305-674-2162 and hit option 4, or email tactnih@msmc.com.
