IVUS VS CAG Guided PCI for Patients With LMB Lesion

Inclusion Criteria: 1. Patients with stable or unstable angina pectoris, asymptomatic myocardial ischemia or attack of myocardial infarction \>24 h; 2. True bifurcation lesion of left main coronary artery (Medina 1,1,1 or 0,1,1); 3. According to coronary angiography, the opening stenosis of the left anterior descending (LAD) and left circumflex (LCX) is more than 50% visually; 4. The operator judges that the lesion is suitable for drug eluting stent(DES) implantation; 5. Branch vessel diameter ≥2.5 mm by visual inspection; Exclusion Criteria: 1. Pregnant or lactating women; 2. Combined with other diseases, life expectancy \<1 year; 3. A surgery is scheduled within 6 months after the operation, and this surgery affects continuous administration of antiplatelet drugs; 4. The dual antiplatelet therapy cannot be tolerated; 5. Follow - up visits required by the protocol cannot be followed, or the investigators believe that the participation of subjects in the trial will increase the risk; 6. Unable to provide written informed consent form, or unable to follow the trial protocol; 7. Participate in another clinical trial of coronary interventional device; 8. Subjects with myocardial infarction within 24 h of onset of chest pain (including ST segment elevation or non - ST segment elevation); 9. Suffer from renal failure requiring dialysis treatment or is undergoing dialysis treatment; 10. Hemoglobin \<9 g/L; 11. Uncontrolled hypertension (systolic blood pressure ≥180 mmHg or diastolic blood pressure ≥ 110 mmHg); 12. Severe cardiac insufficiency (LVEF \<30%); 13. Heart failure complicated with pulmonary hypertension (mean pulmonary artery pressure(mPAP) ≥25 mmHg,pulmonary capillary wedge pressure (PCWP) \>15 mmHg, and pulmonary vascular resistance (PVR)\>3.0WU); 14. Complicated with hypertrophic obstructive cardiomyopathy; 15. Re-stenotic bifurcation lesion; 16. Severe calcified lesions requiring rotational atherectomy; 17. Chronic total occlusion lesion without successful recanalization;