Heartfelt with Dr Melissa Walton-ShirleyView all posts »
Chelation therapy: Wait for scienceNov 5, 2012 00:38 EST
Twenty years ago, as a young cardiologist in rural Kentucky, there were two things that annoyed me most: I always happened to be wearing a pair of floral-print Bermuda shorts when an Amish man would infarct; hence, I often stood in a sea of black and blue trousers and floor-length dresses to explain the situation; and the Amish community's love of chelation therapy. Many times my informed-consent conversation was interrupted to answer questions on the topic. Even my hairdresser gave me a good "what for" once for not recommending it, because her friend "never had another chest pain again" after he underwent the therapy "to clean out his heart arteries." As grateful as I would be for a "miracle" for post-MI patients who seemingly have no options, it is a therapy of suspicious lineage, parented by those who long promoted an unproven therapy for profit. I told my hair stylist, "You tell that gentleman to have a cath before and after chelation, and if his previously blocked arteries are clear afterward, I'll give him my car." I would have won that bet. After today's Trial to Assess Chelation Therapy (TACT) presentation, I'm willing to bet my car a second time that this trial will be misinterpreted by every charlatan on either side of the Mississippi. I can literally hear the hammers across America as fly–by-night stations rev up for revenue. A statistically significant reduction of risk in diabetics and in those with anterior myocardial infarction are impressive, but the jury is still out on this therapy as more study, more safety information, and longer follow-up are needed.
What is chelation? Based on the knowledge that artery blockages are calcified, disodium ethylenediaminetetraacetic acid (EDTA) is used intravenously along with a cocktail of vitamins B and C, heparin, an anesthetic, and magnesium in an effort to "clear out the calcium" from blood vessels. At least that's the way it's advertised. It is a valid therapy for lead poisoning and other metal poisonings, but it can result in severe blood-pressure drops, kidney failure, and dangerously low calcium levels. Chelation is costly at $5000 per therapy and is given as 30, three-hour– long infusions weekly and then 10 maintenance infusions two to eight weeks apart.
What about the trial? It's a tempest of confounding factors. Enrollment was exceptionally slow, and it's no wonder. Any patient who smoked in the past three months was excluded (so probably not a single cohort from Kentucky—kidding, kinda). There were issues with crossover to traditional intervention and surgery. There were less than 900 patients randomized to each group. Many patients quit and others were lost from follow-up. There is something funky about a study in which only diabetics benefit from a therapy. Dr Andrew Weil, an MD who leans far left to the alternative world, shares that skepticism on his blog and viewed chelation therapy as appropriate treatment for proven lead poisoning and the removal of toxic levels of other heavy metals from the body, in keeping with the conventional medical usage. However, he is skeptical of claims that chelation therapy is an effective treatment for cardiovascular disease and the many other conditions for which it is promoted. Dr Weil believes that opting for chelation therapy for heart disease or other serious medical problems can be harmful if it results in the delay of scientifically proven medical treatments and does not recommend such use.
Chelation is an interesting concept. We learned from the COURAGE trial of the great disconnect between high-grade artery blockage and event rates. The concept runs counter to the knowledge that the more calcium we have in a lesion, the less likely the area is to experience plaque rupture, so it's not likely it's the decalcification process that would prevent an AMI but more likely some potential anti-inflammatory benefit on the noncalcified plaque. Perhaps future studies might include pre- and post–IL-1, IL-6, TNF-alpha, CRP, or serum amyloid A levels.
The alternative world of practitioners and patients loves to gamble on nature in a bottle and characteristically needs no evidence to embrace anything that's cheaper, mysterious, antitraditional and self-directed. They are comfortable with word of mouth, intuition, and anecdote. We as practitioners owe it to our patients to wait for science. I'd rather gamble on that.