Different antiplatelet drugs played various role in coronary artery disease. The mechanisms were unclear. Platelet reactivation maybe was one of major causes. Compared with clopidogrel, Ticagrelor is more powerful antiplatelet drug. However, because of increased bleeding and dyspnea risk, both loading double dose and following second dose time had potential risk and inconvenient in routine clinical work, especially in elective PCI of comparable stable patients in Chinese. The benefit and risk should be balanced in such patients. The investigators supposed loading single dose and followed by second routine time dose was superior to clopidogrel and safer than ticagrelor previously prescribed.