SUNDAY, March 10 (HealthDay News) -- There's mixed news from a much-anticipated clinical trial for people who've suffered a heart attack: While a study found that daily high doses of vitamins and minerals did nothing to improve patient outcomes, there was a hint that controversial "chelation" therapy might.

Still, the lead researcher said he's not ready to recommend chelation therapy, in which doctors give patients high-dose vitamins along with special infusions that seek to leach heavy metals from the body.

"These findings should stimulate further research, but are not by themselves sufficient to recommend the routine use of chelation therapy and high-dose vitamins in most patients," said Dr. Gervasio Lamas, chief of the Columbia University Division of Cardiology at Mount Sinai Medical Center, in Miami Beach, Fla.

The trial, which was funded by the U.S. National Institutes of Health, looked at whether chelation therapy might help patients who'd suffered a heart attack. The findings were presented Sunday at the American College of Cardiology (ACC) annual meeting, in San Francisco.

The expensive treatment, which involves dozens of arduous infusions conducted over a period of years, has been offered by certain clinics for decades but has yet to gain U.S. Food and Drug administration approval for heart patients.

However, its reputation got a boost in November when preliminary results from the same trial were presented at the annual meeting of the American Heart Association. Those results did show a modest benefit from chelation therapy for some patients.

The trial involved more than 1,700 patients from the United States and Canada who had suffered a prior heart attack. Most were already taking standard therapies such as daily aspirin, cholesterol-lowering statins or blood pressure medications.

Because chelation therapy also involves daily high-dose vitamins and minerals, Lamas explained that the new analysis tried to separate out the effects of the supplements from that of the chelation itself.

The patients therefore were randomly selected to receive one of four regimens: high-dose vitamin/mineral supplements plus chelation, vitamins/minerals plus a placebo ("dummy") chelation therapy, chelation with placebo vitamin/minerals, or a placebo/placebo group (no actual therapy given). Chelation therapy consisted of 40 three-hour sessions with the IV infusion spread over 18 months, and the doses of vitamins and minerals given were much higher than recommended daily intakes.

After an average follow-up of more than four years, the researchers found no benefit for people who took the daily high-dose vitamins/minerals alone.

"We cannot recommend high-dose oral vitamins and minerals as adjunct therapy for people who have had [heart attacks]," Lamas said at an ACC press briefing on Sunday.

However, the team did see a slight benefit among the group who took the vitamins/minerals in combination with chelation therapy. Twenty-six percent of people in this group experienced some kind of cardiovascular event such as heart attack, stroke or hospitalization for angina (chest pain) -- less than the 32 percent seen among those who got placebo/placebo therapy only.

Still, the gap was not huge and Lamas, who does not use chelation therapy in his own practice, said he cannot recommend it at this time.

"The message really is a cautious message," he said. "We brought something that has been an alternative medicine treatment into the realm of scientific inquiry and found unexpected results that may merit future research. However, we don't think that the results of any single trial are enough to carry this novel hypothesis into daily use for patients."

Two experts who were not connected to the study were less than impressed by the findings.

"Many Americans think that a multivitamin a day is the cure-all to most ailments," said Dr. Tara Narula, associate director of the Cardiac Care Unit at Lenox Hill Hospital in New York City. However, "when it comes to heart disease, this appears to be a myth," she said. "There is no evidence that vitamin and mineral supplementation can be beneficial to cardiac patients."

Dr. Sripal Bangalore is assistant professor in the department of medicine at NYU Langone Medical Center, in New York City. He agreed with Narula that high-dose vitamins are of no help to heart patients, and added that the finding regarding chelation therapy is an isolated one and "needs to be studied further."

For her part, Narula said that "although it is noteworthy that chelation may be helpful, it is an expensive treatment and does carry significant side effects."

Findings presented at medical meetings are considered preliminary until published in a peer-reviewed journal.

More information

There's more on the care of heart attack patients at the U.S. National Heart, Lung, and Blood Institute.