Current consensus papers recommend statin medication to reduce Low density lipoprotein (LDL) cholesterol level less than 100mg/dL (optional 70mg/dL) in patients with coronary artery disease. However, there is lack of solid evidence whether a specific kind of statin have the superiority against other statins in clinical outcomes. Furthermore, recent data have showed that several kinds of statin could have an adverse effect on glucose metabolism and increase the risk of development of diabetes. Carotid Intimamedia thickness (CIMT) is a surrogate marker of atherosclerosis to predict long term cardiovascular outcomes in not only general population but also patients with established coronary artery disease. Consequently, we will evaluate the efficacy of high dose of pravastatin on CIMT, comparing with moderate dose of rosuvastatin in patients with established coronary artery disease. Additionally, we will assess the clinical outcomes of pravastatin after percutaneous coronary intervention as well as adverse outcomes including insulin resistance and new onset diabetes compared with rosuvastatin. Our main hypothesis is that pravastatin 40mg would be non-inferior to rosuvastatin 20mg regarding CIMT at 1 year follow up.