(CNN) -- In results that are stunning cardiologists, a new study shows a "fringe" alternative treatment for heart disease was found to be very effective at preventing heart problems -- but the report is so controversial even its lead author is questioning the results.
The patients in the study had had heart attacks, and were assigned to receive either a placebo or a series of intravenous drug infusions called chelation therapy, an unorthodox treatment that has long been looked down upon by cardiologists.
In the report -- the first large, long-term trial of chelation for heart patients -- the therapy reduced the risk of heart attacks, deaths, strokes and other cardiovascular problems by 18%.
"If this were true, it would be significant. It would put this therapy in the same ballpark as high blood pressure drugs, or drugs used to lower cholesterol," said Dr. Steven Nissen, chair of the department of cardiovascular medicine at the Cleveland Clinic, who doubts the results of the study.
A doctor with the American Heart Association warned that the results "should not be interpreted as an indication to adopt chelation therapy into clinical practice."
"(The study) raises more questions that must be answered before we're ready to act on the observations reported today," said Dr. Elliott Antman, professor of medicine at Harvard Medical School.
Even the lead author of the study tempered his enthusiasm about the results by warning that they might not be valid.
"The most exciting part of this study is that there may be an unexpected signal of benefit," Dr. Gervasio Lamas, chief of Columbia University Division of Cardiology at Mount Sinai Medical Center in Miami Beach, Florida, said in a press release put out by the American Heart Association. "We need to understand whether the signal is true, or whether it occurred by chance."
Doctors who practice chelation welcomed the new study results, which were announced at the American Heart Association's annual meeting in Los Angeles.
These doctors believe chelation can help remove heavy metals from the body. Chelation is approved by the Food and Drug Administration for the treatment of lead poisoning, but doctors are free to use it for other purposes.
"I'll be pushing this data to my patients, and I'll be reaching out to local cardiologists, because chelation should be a part of the regular regimen for heart patients, like taking an aspirin or a statin," said Dr. Kirti Kalidas, who charges his heart patients in Orlando, Florida, around $3,000 for a full round of chelation treatments.
This enthusiasm is exactly what frightens many doctors. Chelation is already popular -- more than 100,000 people said they'd used it in the past 12 months, according to a 2007 report from the Centers for Disease Control and Prevention -- and they fear the new study results will encourage more people to use it.
In 2006, the CDC reported that two children and one adult had died after receiving chelation. They all developed dangerously low calcium levels, which can cause the heart to stop beating.
In this new study, one patient receiving the therapy died and another had a "severe adverse event." Both events were "possibly or definitely related to study therapy," according to the study author's slide presentation. A patient who received a placebo solution also died, and another had an adverse event.
It wasn't clear from the presentation exactly how the patients were harmed, and Lamas, the lead study author, declined to answer questions about the study until the research is published in a medical journal.
Some doctors worry patients will hear only the positive results of the study and not the possible dangers, and would opt for it over proven treatments such as bypass surgery.
"I'm fearful that patients will hear the sales pitch for this treatment and, not being well-versed in medicine, will succumb to the seduction of this therapy," said Nissen, adding that chelation might sound more appealing than an invasive procedure like bypass surgery.
Dr. Kimball Atwood agrees. In an article about the chelation trial, Atwood and his colleagues labeled the $30 million study funded at taxpayer expense by the federal National Institutes of Health "unethical, dangerous, pointless, and wasteful" and called for it to be abandoned.
"These new study results will encourage chelationists, and state medical boards will be loath to step in because the chelationists have this study on their side," said Atwood, a clinical assistant professor of anesthesiology at Tufts Medical Center.
"Every now and then somebody will get killed," he added.
Kalidas, the doctor who practices chelation, disagreed, saying this study would help -- not hurt -- patients.
"Chelation has been lifesaving for hundreds of my patients," he said.
Dangerously low calcium levels
According to the Mayo Clinic, some doctors think chelation helps heart patients because the medication being infused into patients binds to calcium in their clogged arteries, sweeping it away.
But "sweeping" calcium away is a double-edged sword. While it might help unclog coronary arteries, it might also lead to deadly low calcium levels in the blood, as happened to the three people whose deaths were described in the CDC report.
That's one reason why the National Institutes of Health required that the infusions be done at a slow rate -- over a period of three hours or more -- so problems like low calcium levels could be caught easily.
In a series of letters to the study's authors, the Department of Health and Human Service's Office for Human Research Protection cited several concerns about the study, including that the researchers hadn't followed the rules about doing the infusions at a slow rate.
In one letter, the government overseers expressed concern that infusions were performed in "shorter than recommended" times in 440 instances, involving 251 subjects.
The study was stopped from September 2008 until June 2009 to respond to the government's concerns.
A question of significance
In addition to possible safety problems, there are concerns that the study was poorly done and doesn't actually show that chelation works.
In the study, researchers divided the patients into two groups. One group of 839 patients received 40 infusions of a chemical drug solution called disodium EDTA.
Another group of 869 patients received infusions with a placebo solution of salt and sugar water. Neither the patients nor the doctors knew who was receiving which treatment.
Among the patients receiving chelation, 26% went on to have a cardiovascular event, such as death, heart attack or stroke. Among the placebo group, 30% went on to have a cardiovascular event.
According to the authors' analysis, this four-percentage-point difference was barely statistically significant, leading Lamas to note that the difference may have been by chance, not because chelation actually worked.
Further watering down the report is the fact that a relatively large number of patients -- 17% -- dropped out of the study.
Experts say patients usually drop out of studies when things aren't going well -- when they're having bad side effects, for example, or when the therapy isn't working. But since they dropped out, their results can't be included in the study.
"This study was so badly done and the results are so marginal from a statistical perspective that this therapy can't be recommended," said Nissen, the Cleveland Clinic cardiologist.
"Making a treatment decision about a life-threatening disease based on poor-quality scientific data can be dangerous," he added. "History has taught us that when this happens, considerable harm can come to patients."
The future of chelation
Kalidas, the chelation practitioner in Florida, said he hopes these new study results will help persuade insurance companies to start paying for chelation.
But insurance companies usually only pay for treatments that are FDA approved -- and there's little chance the FDA would approve chelation for heart disease based on this study, experts say.
"This would never pass muster at the FDA," said Nissen, the former chairman of the FDA advisory panel that examines applications to put new heart drugs on the market.