A Blinded Study Conducted at Multiple Centers Evaluating Various Doses of an Investigational Agent (BO-653) Against Placebo, for Safety and Effectiveness in Preventing Post-Angioplasty Blood Vessel Re-Closure (Restenosis) in Stented Vessels.

This research study is intended to evaluate the safety and effectiveness of 3 different doses of BO-653, an investigational inhibitor of LDL cholesterol oxidation, when given orally twice a day compared to placebo (an inactive substance) in preventing restenosis (closure of vessel) within six months after stent implantation. Patients must be enrolled into this study within 24 hours after the stenting procedure.

Additionally, over a 1- to 9-month post-stent period, the study will compare the safety and effectiveness of BO-653 versus placebo for measures of coronary artery vessel size by quantitative coronary angiography, major adverse cardiac events, and effects on the oxidative status of plasma lipids and other plasma components.