The coronary images of selective angiography and optical coherence tomography with FFR(Fractional Flow Reserve) values of the intermediate lesions (40-70% stenosis) will be prospectively registered.

The patients with intermediate lesions after CT angiography and invasive coronary angiography will be screened, and optical coherence tomography, FFR and selective CT angiography will be performed. The coronary images and FFR values will be registered, and the patients will be followed-up up to 2 years to investigate the adverse clinical events.

Inclusion Criteria:

• Patients who underwent coronary CT angiography because of chest pain
• Patients who need OCT or FFR evaluation because of intermediate lesions according to invasive angiography (diameter stenosis of 40-70%)
• Age: 20-80 yrs
• Patients who consent and fully understand the protocol
• Patients who consent the clinical follow-up
• Patients who can be followed-up

Exclusion Criteria:

• Patients who had contrast allergy
• Patients who had unstable blood pressure needing the vasopressors
• Patients who had severe left ventricular function (left ventricular ejection fraction<30%)
• Chronic kidney disease who had Cr level of greater than 2.0 mg/dl
• Patients whose expected survival is less than 12 months
• Patients who had a severe valvular disease

Tertiary cardiovascular hospital