In this study, the investigators sought to evaluate the feasibility of estimating external hemodynamic stress acting plaque with the use of invasively measured hemodynamic data from pressure wire pullback tracing.

In addition, the investigators will also evaluate detailed plaque geometry and vulnerability using optical coherence tomography along with the hemodynamic stress.

It has been well known that mechanism of acute coronary syndrome is plaque rupture and occlusion of coronary artery by this plaque rupture. Although current risk assessment for plaque rupture have mainly focused on evaluation of plaque vulnerability. However, according to the general mechanism of material failure, plaque rupture occurs whenever the external hemodynamic stress exceeds the durability of the plaque.

Recently, we evaluated the axial plaque stress, which is axial component of total traction acting on the plaque, and showed that the axial plaque stress possess significantly higher magnitude than previously known wall shear stress.

However, the axial plaque stress in our previous research was measured with computational flow dynamics analysis using coronary artery model from coronary CT angiography.

In this study, we sought to evaluate the feasibility of estimating external hemodynamic stress acting plaque with the use of invasively measured hemodynamic data from pressure wire pullback tracing.

In addition, we will also evaluate detailed plaque geometry and vulnerability using optical coherence tomography along with the hemodynamic stress.

Inclusion Criteria:

• 1. Patients with angina pectoris who are scheduled to do invasive coronary angiography.
• 2. Patients who have moderate (40-70%) stenosis at proximal or mid-portion of major coronary arteries.
• 3. Pressure wire pullback tracing and Optical Coherence Tomography ware successfully performed

Exclusion Criteria:

• 1. Stenosis at distal coronary or small vessel.
• 2. Patients who don't have moderate (40-70%) stenosis at proximal or mid-portion of major coronary arteries. Confirmed by invasive coronary angiography.
• 3. Inadequate quality of Optical Coherence Tomography
• 4. No data of Fractional Flow Reserve or Pressure wire pullback tracing or inadequate data of Fractional Flow Reserve or Pressure wire pullback tracing

Patients with angina pectoris