This chelation seemed safe in this study, where steps were taken to minimize complications and exclude people likely to suffer them, he said. "Further research needs to be done before this can join the mainstream of cardiovascular care."
Other experts questioned the results, especially because 60 more people in the group getting dummy infusions withdrew from the study than in the group getting chelation. Usually, more people in a treatment group drop out because of side effects, said Dr. Christie Ballantyne, a Baylor College of Medicine heart specialist. To find the opposite is "a red flag" that suggests those who got dummy treatments found that out and decided to drop out.
"There's something funky going on here," Ballantyne said. "It raises questions about study conduct," especially since a difference of one or two people or complications could have nullified the small overall benefit researchers reported.
Dr. Clyde Yancy, a Northwestern University cardiologist and a former Heart Association president, agreed.
"It's funny business," he said. "I've never seen a study in which one in five people withdrew consent."
The study's leader, Dr. Gervasio Lamas of Mount Sinai Medical Center in Miami, said: "The trial needs to be taken for what it is — a step towards future investigation."
It initially aimed to enroll 2,400 people in the United States and Canada but recruitment lagged and the goal was reset to 1,700.
In 2008, a group of scientists published a long article criticizing the trial, saying participants had not been warned that others had died from chelation. More than half of the doctors running the study make money by selling chelation treatments — a conflict of interest, they complained.
Investigations by the Office for Human Research Protections and the Food and Drug Administration found that several doctors doing the study had been accused of poor practices by state medical boards or involved in insurance fraud, and at least three were convicted felons. That did not prevent them from doing federal research, the government decided, and let the study go on after corrective steps. By that time, 1,500 participants had already been enrolled.
Marilynn Marchione can be followed at http://twitter.com/MMarchioneAP