番茄社区

SAN FRANCISCO -- Vitamins alone won't improve outcomes for patients who've had a heart attack, but they do appear to have additive benefits when given in conjunction with chelation therapy, researchers reported here.

In further analyses of the Trial to Assess Chelation Therapy (TACT), MI patients who had both high-dose vitamins and chelation therapy were significantly less likely to reach a combined cardiovascular endpoint over 5 years than those who had placebo in both instances, Gervasio Lamas, MD, of Mount Sinai Medical Center in Miami Beach, Fla., reported during a late-breaking clinical trials session at the American College of Cardiology meeting here.

"The message here, I think, is a cautious one," Lamas said. "We've moved something that has been an alternative medicine into perhaps the realm of scientific inquiry, and found some unexpected results that merit further research."

But he warned that he doesn't think the "results of any single trial are enough to carry this novel hypothesis into daily use for patients who've had acute MI."

However, Magnus Ohman, MD, of Duke University Medical Center, noted that the trial was well-designed and had a clear outcome: "We have a 2-by-2 factorial design, we have a significant reduction with vitamins and chelation versus placebo-placebo, yet your conclusion is, 'maybe not.'"

"So I'm wondering," he continued, "if we do a trial and we have an endpoint that is unusual and is a statistically significant finding, why are you holding back?"

Ohman told 番茄社区 he wouldn't necessarily recommend chelation therapy to his patients at Duke University, but if they told him they were going to try it, he wouldn't discourage them.

When it was presented at the American Heart Association meeting last fall, the TACT trial showed that chelation therapy reduced a composite cardiovascular endpoint in patients who've had an MI -- a finding that was surprising to all and unsettling to many cardiologists, who had been dismissive of chelation.

But most chelation practitioners will use concurrent high doses of anti-oxidant vitamins and minerals in conjunction with chelation. To rule out this potential confounding, the trial was conducted in a 2-by-2 factorial fashion, in which once patients were randomized to either the therapy or placebo, they were also randomized to either vitamins (3 high-dose capsules per day) or placebo.

The TACT Vitamin trial enrolled the full 1,708 patients and assessed the same primary composite endpoint of time to first occurrence of either death, MI, stroke, coronary revascularization, or hospitalization for angina.

Overall, Lamas and colleagues found no difference between those on vitamins or those on placebo in terms of the primary endpoint (37% in placebo group versus 34% in high-dose vitamin group), and there were no significant differences in any individual components of the primary endpoint.

But when looking at all four groups, they found that those who had chelation and vitamins had a significantly reduced risk of the primary endpoint compared with those who had placebo in both instances (HR 0.74, 95% CI 0.57 to 0.95, P=0.016).

Lamas said the mechanisms by which a combination of high-dose vitamins and chelation therapy might benefit these patients are unclear, but are deserving of further research.

During the session, he equated the results to those from a phase I or II randomized controlled trial, and that the idea of chelation therapy and vitamins "has now become, I think based on TACT, a novel hypothesis."

"It might give us a little window into a mechanism that we have not previously thought of," Lamas said, cautioning, however, that "we are far from carrying this novel hypothesis and applying it to patients."

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