Inclusion Criteria:  age between 18 and 80 years;1 or more CTO vessels (≥2mm in diameter)  Exclusion Criteria:  successful PCI for all CTO lesions; ST segment elevation myocardial infarction (STEMI) during the past 3 months; planed coronary artery bypass grafting (CABG) within 3 months; valvular heart disease or congenital heart disease; cardiomyopathy; heart failure with NYHA (New York Heart Association) class III or above; persistent atrial fibrillation or complete left bundle branch block; severe liver, kidney, or lung diseases