TACT is an National Institutes of Health-sponsored, randomized, double-blind, placebo-controlled, 2 × 2 factorial clinical trial testing the benefits and risks of 40 infusions of a multicomponent disodium EDTA chelation solution compared with placebo and of an oral, high-dose multivitamin and mineral supplement. TACT has randomized and will follow up 1,708 patients for an average of approximately 4 years. The primary end point is a composite of all-cause mortality, myocardial infarction, stroke, coronary revascularization, and hospitalization for angina. A 900-patient substudy will examine quality-of-life outcomes. The trial is designed to have >85% power to detect a 25% relative reduction in the primary end point for each treatment factor. Enrollment began in September 2003 and was completed in October 2010.