Chelation may reduce mortality, cardiovascular events in diabetics after MI

Chelation reduced cardiovascular disease events in patients with diabetes who had a previous myocardial infarction (MI), a recent study found.

The Trial to Assess Chelation Therapy (TACT) included 1,708 patients age 50 or over with a history of MI, of whom 633 had diabetes mellitus. Patients were randomized to 40 infusions of either ethylene diamine tetraacetic acid (EDTA) chelation or placebo, and they were followed for a median of 55 months. Results were published by Circulation: Cardiovascular Quality and Outcomes on Nov. 19.

Patients without diabetes saw no significant benefit from the EDTA chelation therapy; however, patients with diabetes had a substantial reduction in cardiovascular events. In the diabetic subgroup, the study's primary end point (death, reinfarction, stroke, coronary revascularization or hospitalization for angina) was 25% in the active group versus 38% in the placebo group (hazard ratio [HR], 0.59; 95% CI, 0.44 to 0.79), a finding that remained significant after adjustment. The number needed to treat to reduce 1 primary end point over 5 years was 6.5.

The study authors concluded that EDTA chelation markedly reduced cardiovascular events in post-myocardial infarction patients age 50 and over with diabetes. They cautioned that these results were from a subgroup, although a prespecified one, of a larger trial, so they require replication. The authors speculated as to the possible mechanism of the effect, suggesting that metals bind to glycation end products, accumulating in tissue and promoting inflammation. The fact that the survival and event curves continued to separate long after the intervention stopped suggests that removal of the metals may have had long-term benefit for the patients.

The study was limited by an unexpectedly high dropout rate, but it was higher among placebo patients than intervention patients, which would cause an underestimation of the intervention's effect. The results support the initiation of more trials of chelation in patients with diabetes and vascular disease, the authors said. In the meantime, there is not yet sufficient evidence to support routine use of chelation for these patients, they concluded.