Invasive Versus Non-invasive Approach in Symptomatic Patient With Non-High Risk Coronary Artery Stenosis

Prior treatment

• Known CAD with previous MI, percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG)

Other illness

• Diagnosed or suspected acute coronary syndrome (ACS) requiring hospitalization or urgent or emergent testing (elevated cardiac troponin or CK-MB)
• High risk CAD (left main stenosis ≥ 50%; anatomically significant 3-vessel disease with ≥70% stenosis)
• Hemodynamically or clinically unstable condition (systolic BP \< 90 mmHg, ventricular arrhythmias, or persistent resting chest pain in ischemic nature despite adequate therapy
• Known true anaphylaxis to contrast medium (not allergic reaction but anaphylactic shock)
• Known significant congenital, severe valvular or cardiomyopathic (hypertrophic or dilated cardiomyopathy, or any other forms) process which could explain cardiac symptoms.
• Non-cardiac co-morbid conditions are present with life expectancy \<2 year or that may result in protocol non-compliance (per site investigator's medical judgment)

Lab values

• Severe left ventricular systolic dysfunction (ejection fraction \<30%)

Other

• Intolerance to Aspirin, Clopidogrel, or Heparin.
• Unwillingness or inability to comply with the procedures described in this protocol.

• Subject age ≥19 years old
• Patients with new or worsening chest pain syndrome, equivalent symptoms, or abnormal laboratory test findings (suspected ischemic changes in electrocardiography, regional wall motion abnormality in echocardiography, or coronary calcium score \> 100) suspected for clinically significant CAD who are evaluated by CCTA
• Any other clinical circumstance in which physician judged to proceed CCTA
• Obstructive CAD in CCTA (≥50% diameter stenosis)
• Subject who can verbally confirm understandings of risks, benefits, and treatment alternatives of receiving invasive approach and he/she or his/her legally authorized representative provides written informed consent prior to any study related procedure.