Despite the advanced technology in percutanous coronary intervention over the past decade, restenosis still affects a significant number of patients. Restenosis still occurs in 20-30% of patients up to 6 month after coronary angioplasty. The clinical implication of restenosis is recurrence of symptoms of ischemic heart disease, need for repeated revascularization, acute myocardial infarction or even sudden death within months after coronary intervention. Various studies have shown that stent design, stent coating and stent strut thickness may determine event-free survival. Cobalt chromium coronary stents are increasingly being used in percutaneous coronary interventions due to its better properties. The aim of this study is to compare cobalt chromium coronary stents with conventional stainless steel stents when both are used for coronary vessel stenting.