In a new study, chelation therapy—an unproven alternative treatment for heart disease—modestly reduced cardiovascular events in older adults who’d suffered a prior heart attack. findings weren’t conclusive but provide guidance for future research.

Chelation is a chemical process in which certain compounds bind heavy metals and minerals and hold them tightly. In chelation therapy, chelation compounds are given intravenously to remove toxic heavy metals—such as lead, iron and copper—from the blood before they can cause damage. cium disodium EDTA, for example, is approved by the U. S. Food and Drug Administration for treating lead poisoning.

Some physicians and alternative medicine practitioners recommend chelation therapy as a complement to standard therapies for cardiovascular disease. Its use as an alternate treatment for this and other disorders has grown dramatically in the United States in recent years. Disodium EDTA, the compound commonly used in chelation therapy for cardiovascular disease, isn’t approved by the FDA but can be ordered from compounding pharmacies for individual use. Thus far, its ability to prevent cardiovascular events has been supported only by anecdotal evidence.

To take a closer look, researchers enrolled over 1,700 adults ages 50 and older in the United States and Canada. The participants had all survived a heart attack on average about 4. 5 years prior to enrollment. The trial was sponsored by NIH’s National Heart, Lung and Blood Institute (NHLBI) and National Center for Complementary and Alternative Medicine (NCCAM).

Participants were assigned randomly to receive a course of 40 infusions of either a disodium EDTA chelation solution or an inactive placebo. They were also randomly assigned to receive high doses of oral vitamins and minerals or an identical placebo. Most participants took standard medicines for heart attack survivors, such as aspirin, beta blockers and statins. After the infusions, they were followed for a minimum of 1 year and up to 5 years. Journal of the American Medical Association.

The researchers found a clinically modest but statistically significant benefit of chelation therapy. The study assessed a combined endpoint that included death, recurrent heart attack, stroke, hospitalization for angina (chest pains that are sometimes a sign of an impending heart attack), and coronary revascularization (coronary stenting or bypass surgery). Fewer participants experienced any of these events in the chelation group (222, or 26%) than in the placebo group (261, or 30%). The study didn’t have enough patients to assess a difference in mortality.

The trial demonstrated that chelation therapy can be safely administered when rigid quality control parameters are in place, and that, under these conditions, therapy has modest benefits,” says lead investigator Dr. Gervasio A. Lamas of Mount Sinai Medical Center in Miami.

Further research is needed to fully understand these results before this treatment can be applied to the routine clinical care of heart attack patients,” says NHLBI Director Dr. Gary H. Gibbons. We do not yet know whether this therapy can be applied to most people with heart disease, which patients may potentially benefit from it, or how it may work.