Invasive Versus Non-invasive Approach in Symptomatic Patient With Non-High Risk Coronary Artery Stenosis (SMART-STEP)

Inclusion Criteria: 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) suspicious 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. Exclusion Criteria: 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 CAD with previous MI, percutaneous coronary intervention (PCI), coronary artery bypass graft (CABG) 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. Severe left ventricular systolic dysfunction (ejection fraction <30%) Intolerance to Aspirin, Clopidogrel, or Heparin. 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) Unwillingness or inability to comply with the procedures described in this protocol.