An alternative treatment for heart disease could in fact have a benefit to patients who use it, a new study shows.

Chelation therapy involves infusing the bloodstream with agents designed to remove heavy metals such as lead or iron from the bloodstream. Those metals have been linked to the formation of plaque in the arteries, which can lead to heart disease and stroke.

The $31 million, U.S. government-sponsored study looked at 1,700 patients who suffered previous heart attacks at 134 centres in the United States and Canada.

One group received a combination chelation solution along with vitamins, blood thinner and an anesthetic, while the other group received a placebo solution.

The participants received infusions over the course of nearly a year, with each infusion lasting about three hours. The participants then reported on their heart health one year later.

The study found that 26 per cent of the patients who received the chelation therapy had a stroke, a heart attack, a hospitalization for chest pain, angioplasty with a stent, or died.

In the placebo group, 30 per cent of patients had one of these events.

The findings are statistically significant.

The treatment's strongest effects were on those with diabetes, with 39 per cent fewer strokes and heart attacks reported among those participants.

The result of the study has surprised researchers. Chelation therapy, which has been used for some five decades, has long been considered a fringe therapy.

“It is certainly a surprise to us, and to cardiologists, that the study proved there is something to chelation therapy,” said Dr. Fred Hui, one of the investigators and a doctor who offers chelation therapy in Ontario.

“This study is shaking up thinking,” said Dr. George Wyse of the Libin Cardiovascular Institute, who was part of a Canadian study of chelation presented in 2001 that suggested the therapy didn’t help patients.

“I think we were all surprised,” he added. “It was like opening a door and throwing a hand grenade in and closing the door. Now we have to explain why the results are the way (they) are and I think it will lead to more research.”

But other doctors say the research for the study was “flawed,” that more scrutiny would be “waste of time and money” and that the therapy is "dangerous,” though the study didn't find that.

“This study was carefully monitored. There was no evidence of harm, but who knows once a treatment is approved and out there what kind of harm might show up,” Wyse said.

According to the American Heart Association, more research is needed to confirm the findings and to understand the mechanisms of action for the benefits seen in the trial.

“We can’t infer chelation therapy is proven and now should be offered, but it is a step in the right direction,” Hui said.

Meanwhile, chelation’s popularity seems to be growing.

Some 100,000 people a year in North America swear by it, paying $5,000 for a series of 20 treatments.

It is also used for autism and Alzheimer’s, although it remains unapproved for those off-label uses.

With a report from CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip