To find out the safety and efficacy of Optical Coherence Tomography (OCT) in the evaluation and treatment of angiographically borderline coronary artery lesions in a Chinese population, and to compare the effectiveness of OCT versus SPECT in treating such subjects. All the participants included in the study will be those that are found to have borderline coronary artery lesions on coronary angiography, in whom the investigators feel that OCT will be useful to assess whether PCI will be of benefit to the treatment of the lesion pathology, or whether optimal medical therapy is the most appropriate treatment modality. Those participants who declined OCT will be offered SPECT as an alternative method to assess and treat the borderline coronary artery stenosis.

It is estimated that OCT guided "PCI or not" has a non-inferiority to SPECT's in the borderline coronary artery stenosis.

Inclusion Criteria:

• The inclusion criteria for this study will be only those participants in whom diagnostic coronary angiography revealed borderline coronary artery lesion. These participants will undergo the OCT procedure, or alternatively ECT.

Exclusion Criteria:

• Exclusion criteria will be those participants with previous cardiogenic shock, stroke, renal dysfunction, and acute or chronic total occlusion coronary lesions.