Objective:To investigate the clinical effectiveness and safety of double dosage of clopidogrel and ticagrelor in patients with clopidogrel resistance after percutaneous coronary intervention(PCI). Methods:A total of 188 patients with clopidogrel resistance(platelet inhibition rate<30%)after PCI were randomly divided into the conventional clopidogrel group (group A,n=64),the double dosage of clopidogrel group (group B,n=61)and the ticagrelor group (group C,n=63). The platelet inhibition rate of the adenosine diphosphate (ADP) pathway was tested at the seventh day after PCI,high sensitivity C reactive protein (hsCRP)was measured at the first and the seventh day after PCI,the incidence rates of major adverse cardiovascular events (MACE)and slight bleeding were compared among the three groups at the first month and the sixth month follow-up. Results:At the seventh day after PCI,the platelet inhibition rates in group B and C were significantly higher than that in group A (both P < 0.05),and the rate in group C was higher than that in group B(P < 0.05). At the first day after PCI,no significant difference in hsCRP was observed among the three groups (P > 0.05). However,at the seventh day after PCI,hsCRP in group B and C was significantly reduced compared with the group A,respectively(both P < 0.05),and hsCRP in group C was lower than that in group B(P < 0.05). At the first month follow-up,there were no significant differences in the incidence rates of MACE and the slight bleeding among the three groups(P > 0.05). At the sixth month follow-up,the incidence rates of MACE in group B and C were significantly reduced compared with group A(both P < 0.05),and the rate in group C was lower than that in group B (P < 0.05),but there was still no significant difference in the incidence rate of slight bleeding among the three groups (P > 0.05). Conclusion:In patients with clopidogrel resistance after PCI,ticagrelor is more effective without increasing adverse reactions.