Removing metals from the body through a controversial treatment has little effect on the long-term health of people who've previously suffered a heart attack, according to the results of a government-funded trial released Tuesday.
Researchers found no difference in how many of 1,708 participants died in the four and a half years after they received either so-called chelation therapy or drug-free placebo infusions, and only a small decline in the proportion that needed stents or other heart procedures following chelation.
The fact that many patients dropped out of the study - more than one in six - makes even that small benefit undependable, researchers said.
"I would consider it to be essentially an unreliable finding," said cardiologist Dr. Steven Nissen from the Cleveland Clinic Foundation, who wrote an editorial published with the study.
He called chelation "a form of quackery" that some vulnerable patients look to when they're facing bypass surgery, for example.
"The biggest danger here is that people get diverted from established therapies that we know work, to this sort of therapy that doesn't work," Nissen told Reuters Health.
During chelation therapy, a drug that binds to metals including calcium, lead and iron is infused into the bloodstream - allowing those metals to be more easily excreted in the urine.
The technique has been approved by the U.S. Food and Drug Administration (FDA) to treat lead poisoning, but has also been used for a range of other conditions, including on kids with autism (see Reuters Health story of Dec 21, 2012 here:).
In 2010, the FDA warned companies to stop marketing chelation for autism and cardiovascular disease as well as other untested and unapproved uses.
In response to the new study, an FDA spokesperson told Reuters Health in an email, "There are no chelation therapy products approved to treat heart disease. Additionally, all FDA-approved chelation therapy products require a prescription because they can only be used safely under the supervision of a healthcare practitioner."
Researchers lead by Dr. Gervasio Lamas from Mount Sinai Medical Center in Miami Beach randomly assigned older adults with a prior heart attack to receive 40 rounds of chelation therapy or drug-free placebo infusions at 134 clinics in the U.S. and Canada. Each infusion lasted about three hours.
Lamas and his colleagues then tracked study volunteers for the next four and half years, on average, to see who developed heart disease. They found no difference based on treatment in the proportion of people who suffered a second heart attack - between six and eight percent - and the proportion who had a stroke - about one percent.
However, when data on strokes, heart attacks, deaths, heart surgeries and hospitalizations were combined, people who'd had chelation did slightly better. Twenty-six percent of them had one of those outcomes - most often surgery - compared to 30 percent of the placebo group, according to findings published in the Journal of the American Medical Association (JAMA).
COSTS AND SAFETY CONCERNS
About twice as many people developed low calcium levels after chelation than after placebo infusions.
Lamas said that in his trial, chelation was safe. The concern is that if some clinics perform the infusions too quickly, a patient's calcium levels could drop dangerously low and cause heart rhythm problems.
A typical package of chelation treatments costs about $2,000 to $5,000 and is often not covered by health insurance.
Lamas said he would not recommend chelation to everyone recovering from a heart attack, but that he is more optimistic than he was before starting the study.
"There are some real anchors in the treatment of patients who've had a prior heart attack," such as aspirin. "Those anchors need to be tried first," he told Reuters Health.
Referring to the evidence doctors have for traditional treatments of atherosclerosis, he said, "You can't compare that sheer weight of data to 1,700 patients."
Still, that doesn't mean all heart patients should be discouraged from trying chelation in a safe setting, according to Lamas.
"If a patient asked me about it, it would depend on the patient's circumstances," he said. "If they were very ill (and) standard medical therapy had not worked, then I think one has to individualize and discuss it with the patient."
In their paper, he and his colleagues wrote that while their new evidence could be used to help design additional studies, that evidence is too weak to support using chelation in the average heart attack patient.
In a second editorial published with the report, JAMA editors pointed out the controversies that came up during the study - including allegations about researchers at some of the study sites - and said that the possible benefit of chelation, if any, appears to be small.
"This evidence and information should serve to dissuade responsible practitioners from providing or recommending chelation therapy for patients with coronary disease and should discourage patients with previous (heart attack) from seeking this therapy with the hope of preventing subsequent cardiovascular events," Editor in Chief Dr. Howard Bauchner and his colleagues concluded.