BACKGROUND:Many trials have shown that 3-hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA) reductase inhibitors reduce the incidence of cardiovascular events and mortality. One method of decreasing the incidence of cardiovascular events could be to reduce the progression of coronary atherosclerosis, and a recent study found that atorvastatin can cause coronary plaque to regress. To generalize this finding, using conventional HMG-CoA reductase inhibitors at many Japanese centers, randomized trials of pitavastatin and atorvastatin will be conducted with patients with acute coronary syndrome (ACS). METHODS AND RESULTS:Patients with ACS who have undergone successful percutaneous coronary intervention under intravascular ultrasound guidance will be studied. They will be randomly allocated to pitavastatin or atorvastatin groups and followed up for 8-12 months. The primary endpoint will be the percent change in coronary plaque volume, and secondary endpoints will include absolute changes in coronary plaque volume, serum lipid levels and inflammatory markers. The safety profile will also be evaluated. CONCLUSIONS:This study will examine the ability of HMG-CoA reductase inhibitors to regress coronary plaque in Japanese patients with ACS and the findings should help to improve the prognosis of such patients and clarify the involved mechanisms.