A treatment that removes heavy metals from the body has long been touted as an alternative therapy to combat hardening arteries.
Now a 10-year, $31 million clinical trial has found that chelation therapy helps heart attack patients slightly reduce their risk of serious problems, but not enough for the researchers to encourage cardiologists to offer it to their patients.
The findings came in for harsh criticism from other experts who worried that the results might encourage patients to take up a still unproven and potentially dangerous treatment.
"It's a type of medical quackery that has been around for many decades," said Dr. Steven Nissen of the Cleveland Clinic.
Chelation therapy was introduced around World War II as an antidote to an arsenic-based poison gas called Lewisite. The drug tested in the JAMA study, called ethylenediamine-tetraacetic acid, was used to treat lead poisoning in Navy personnel who repainted ships' hulls.
About 50 years ago, it came into vogue as an apparent way to remove mineral-rich deposits of plaque that can cause arteries to harden in a condition known as atherosclerosis.