LOS ANGELES — To the surprise of many cardiologists, a controversial alternative therapy proved beneficial to people with heart disease, reducing the rate of death and cardiovascular problems in a clinical trial, researchers said on Sunday.
The benefit of the treatment, known as chelation therapy, barely reached statistical significance, and there were questions about the reliability of the study. Even the investigators in the trial said the results were insufficient by themselves to justify recommending use of the treatment.
Still, the unexpected finding should provide some vindication to the National Institutes of Health for sponsoring the $30 million study, which was plagued by delays and problems.
“There may be a biological effect and that biological effect should be taken seriously,” and “pursued with additional research,” Dr. Gervasio A. Lamas of Mount Sinai Medical Center in Miami, the lead investigator, said at a news conference here at the annual scientific meeting of the American Heart Association.
Dr. Elliott Antman, representing the heart association, applauded the National Institutes of Health for sponsoring the study while also expressing caution. “Intriguing as these results are, they are unexpected and should not be interpreted as an indication to adopt chelation therapy into clinical practice,” said Dr. Antman, a cardiologist at Brigham and Women’s Hospital in Boston.
Chelation therapy involves the infusion of agents that remove metals from the bloodstream.
More than 100,000 Americans with heart disease undergo chelation therapy each year, at a cost of about $5,000 per course of treatment, experts here said. The hypothesis is that chelation can remove the calcium that is a contributor to arterial plaques.
But skeptics said there was not enough evidence backing chelation therapy to even begin a clinical trial. Proponents of the study said that since chelation therapy was already widely used, it should be subject to the same rigorous scientific testing used to study conventional pharmaceuticals.
And some skeptics were not persuaded at all. Dr. Steven Nissen, head of cardiovascular medicine at the Cleveland Clinic, said the study was “fatally flawed,” with many of the doctors involved being on the fringes of medicine and many patients dropping out of the trial. He said if people got the mistaken idea from the study that chelation was beneficial “it would be a public health catastrophe.”
The study, which began enrolling patients in 2003, was plagued by problems from the start. It fell way behind its goal of recruiting nearly 2,400 patients in three years. The trial was also suspended in 2008 for investigations by government agencies, one over conduct at trial sites and the other about whether patients were being adequately informed that chelation can cause death. The study was allowed to resume the next year, after some changes were made.
The trial ended up with 1,708 patients at 134 centers in the United States and Canada. The patients all had had previous heart attacks.
Half the patients received the chelation therapy, a synthetic amino acid called disodium ethylene diamine tetra acetic acid, or EDTA, as well as other substances. These were given by infusion every week for 30 weeks, followed by 10 more infusions at intervals of two to eight weeks. The other half received infusions of placebo.
After a follow-up of 55 months, 26 percent of those who received chelation therapy had died, suffered a heart attack or stroke, had a procedure to reopen a coronary artery or had been hospitalized for angina. That was less than the 30 percent for those who received a placebo, a difference that was barely statistically significant.
Doctors said there were reasons for caution.
Virtually all the of difference between the treatment and the placebo groups occurred in the third of patients who had diabetes. The placebo contained some sugar, which conceivably could have harmed the diabetics. Also, at least within the first two years, the chelation therapy did not improve physical functioning or psychological well being, according to surveys of the patients.
Dr. Mark A. Creager, a cardiologist at Brigham and Women’s Hospital who was not involved in the study, said the chelation infusion also contained a high dose of vitamin C and the blood thinner heparin. It could be that one of those ingredients, not the chelation agent, were responsible for any benefit, he said.
Dr. Lamas, the lead investigator, said the chelation treatment was well tolerated. But he said investigators did not yet know why some patients receiving the therapy dropped out of the trial.
Another study presented at the heart meeting on Sunday found coronary bypass surgery superior to the use of stents for patients with diabetes and multiple heart blockages.
The trial involved 1,900 patients followed for five yeas. About 27 percent of those who received stents either died or had a heart attack or stroke, compared with about 19 percent of those undergoing bypass surgery. There was an increase in stroke risk with surgery, but that was outweighed by fewer deaths and heart attacks.
Previous studies had already suggested that surgery was better for diabetic patients with severe coronary disease, and practice guidelines already say it is “reasonable” to choose surgery. But the new study, sponsored by the National Institutes of Health, shows the same result even using modern drug-covered stents.
About 700,000 Americans undergo artery opening procedures for more than one blood vessel each year, and about 25 percent of them have diabetes, according to the investigators.
The study results were also published online by the New England Journal of Medicine. Johnson & Johnson and Boston Scientific provided the stents used in the study.
Chelation Therapy Shows Slight Benefit in Heart Disease Clinical Trial
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Chelation Therapy Shows Slight Benefit in Heart Disease Clinical Trial
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Chelation Therapy Shows Slight Benefit in Heart Disease Clinical Trial
