A 68-year-old male was complained of chest pain for two years and fatigue for one week.He was admitted to other hospitals two years ago because of severe chest pain.A diagnosis of acute non-ST segment elevation myocardial infarction (NSTEMI) was made.But the coronary angiography was refused by himself.After effective conservative treatment,he got better and discharged.A regular administration of aspirin,metoprolol and simvastatin was taken.No recurrent sympotoms occurred.However,he felt fatigue and palpitation after 30-m walking one week ago without predisposing factors.