The purpose of this study is to determine ticagrelor combining with low molecular weight heparin is effective and safe during PCI or not.

Ticagrelor is a new drug compared with clopidogrel. It has a stronger antiplatelet capacity. After PCI，whether using low molecular weight heparin can make patients better prognosis or not, What's more，full amount or half amount low molecular weight heparin?, also investigators want to explore that whether it may lead to more bleeding events.

Inclusion Criteria:

1. Age ≥18 years old and ≤75 years ;
2. unstable angina, non-ST segment elevation acute myocardial infarction, old myocardial infarction, or confirm the presence of myocardial ischemia;
3. voluntary participation in clinical trials, and informed consent;

Exclusion Criteria:

1. acute ST segment elevation myocardial infarction, stable angina pectoris;
2. aspirin allergy or resistance;
3. consolidated stroke, chronic obstructive pulmonary disease and other ticagrelor contraindications;
4. patients have coagulopathy;
5. can not be continued for one year with aspirin and treatment of dual antiplatelet ticagrelor;
6. can not complete revascularization;
7. NYHA ≥Ⅲ level or left ventricular ejection fraction <40%;
8. severe liver and kidney dysfunction (ALT and AST were more than three times the upper limit of normal, creatinine clearance less than 30ml / min-1.1.72m-2);