Efficacy and Safety Study of Ticagrelor

Inclusion Criteria: * 1.Clinical diagnosis of ACS 2.undergoing PCI 3.with clopidogrel resistance Exclusion Criteria: * 1.any contraindication against the use of clopidogrel and ticagrel 2.Contradiction to aspirin and contrast medium 3.Life expectancy less than 1 year 4.Tumor or inflammatory diseases5. fibrinolytic therapy within 24 hours before randomization 6.a need for oral anticoagulation therapy 7. an increased risk of bradycardia 8.concomitant therapy with a strong cytochrome P-450 3A inhibitor or inducer 9.a history of asthma.