<qa>  What is the most common cause of ST in CAD patients?The fatality of stent thrombosis ST in patients with coronary artery disease CAD undergoing percutaneous coronary intervention PCI is approximately 50 and clopidogrel is an important anti-platelet drug for prevention of ST. CAD patients implanted with stent including bare metal stent BMS and drug eluting stent DES are recommended to receive dual anti-platelet treatment DAPT, i.e. clopidogrel along with aspirin, for at least one year to reduce the incidence of ST by up-to-date guidelines. However, due to the variability of anti-platelet effect of clopidogrel, regular dose 75 mg daily of clopidogrel administered cannot achieve enough inhibition of platelet aggregation in 20-30 of total patients, which is named as clopidogrel low responsiveness CLR, and the morbidity of thrombosis including in CAD patients is still 10. 