Abstract: Objective:To compare the clinical effects of different doses of dexmedetomidine on the percutaneous coronary intervention(PCI) in patients with acute coronary syndrome.Methods:A total of 80 acute coronary syndrome patients treated with PCI were randomly divided into the high dose group and low dose group(40 cases each group).The low dose group and high dose group were sedated with 0.3 μg/kg and 0.6 μg/kg of dexmedetomidine,respectively.The perioperative heart rate,blood pressure,postoperative stress index and adverse reaction between two groups were compared.Results:The systolic blood pressure,diastolic blood pressure and heart rate in high dose group were significantly lower than those in low dose group at T₁ to T₅ after the start of operation(P<0.05 to P<0.01).The levels of cTnI,CK-MB,BNP,hs-CRP,IL-6 and TNF-α in high dose group were significantly lower than those in low dose group after 2 days of operation(P<0.01).The difference of the adverse reaction in two groups was not statistically significant(P >0.05).Conclusions:The application of 0.6 μg/kg of dexmedetomidine in acute coronary syndrome patients treated with PCI has good sedation effects and low stress response,which is worthy of clinical application.