Impact of Coronary CT Angiography, Physiologic Assessment and Pharmacotherapy on the Clinical Outcomes

The investigators aim to investigate the prognostic implication of stenosis and plaque features on coronary CT angiography (CCTA), physiologic assessment, and pharmacotherapy after invasive coronary angiography.

Stenosis severity, plaque features, and myocardial ischemia have been known as important indicators in diagnosis and prognostication of patients with coronary artery disease. Invasive physiologic indies such as fractional flow reserve (FFR) are used to define ischemia-causing stenosis in the catheterization laboratory. FFR represents maximal blood flow to the myocardium supplied by an artery with stenosis as a fraction of normal maximum flow. The FFR-guided strategy was reported to improve the patients' outcomes in comparison with the angiography-guided strategy. However, clinical events still occur in patients with FFR \>0.80, and invasive therapy did not improve prognosis in patients with moderate to severe ischemia compared to optimal medical therapy in the ISCHEMIA trial. In the recent report, the prognosis in the vessel with FFR \>0.80 was associated with high-risk plaque characteristics on coronary CT angiography (CCTA). Likewise, incorporation of stenosis and plaque features and myocardial ischemia may provide better risk stratification of patients with coronary artery disease than evaluating each attribute alone. Recent proposed novel measurement such as pericoronary inflammation or epicardial fat metrics and lesion-specific or vessel-specific hemodynamic parameters derived from CCTA has also been known as a robust prognostic predictor. In addition, antiplatelet agents and lipid-lowering medication such as aspirin, clopidogrel, or statin are commonly used for primary and secondary prevention of adverse cardiovascular events. However, the relationship of combination and dosage of those drugs with prevention of plaque progression and clinical outcomes has not been fully understood. Accordingly, the investigators aim to find the prognostic implications of stenosis and plaque features, fat metrics on CCTA along with physiologic assessment and pharmocotherapy according to the different treatment strategies.

Eligibility Criteria:
1) Deferral of PCI group

Inclusion Criteria:

1. Age ≥ 20 years
2. Patients who undergo CCTA within 90 days before FFR measurement by clinical needs
3. Patients with a vessel determined to defer revascularization after FFR measurement.

Exclusion Criteria:

1. Left ventricular ejection fraction \< 35%
2. Acute ST-elevation myocardial infarction within 72 hours or previous coronary artery bypass graft surgery
3. Abnormal epicardial coronary flow (TIMI flow \< 3)
4. Failed FFR measurement
5. Planned coronary artery bypass graft surgery after diagnostic angiography
6. Poor quality of CCTA which is unsuitable for plaque analysis
7. Patients with a stent in the target vessel

2) PCI group

Inclusion Criteria:

1. Age ≥ 20 years
2. Patients who undergo CCTA within 90 days before FFR measurement by clinical needs
3. Patients with a vessel that undergo stent implantation and FFR measurement both before and after revascularization (pre-PCI FFR and post-PCI FFR).

   * Patients with multiple vessels that meet inclusion criteria of the deferral of PCI group and PCI group will be assigned to the PCI group.

Exclusion Criteria:

1. Left ventricular ejection fraction \< 35%
2. Acute ST-elevation myocardial infarction within 72 hours or previous coronary artery bypass graft surgery
3. Abnormal epicardial coronary flow (TIMI flow \< 3)
4. Failed FFR measurement
5. Planned coronary artery bypass graft surgery after diagnostic angiography
6. Poor quality of CCTA which is unsuitable for plaque analysis
7. Patients with a stent in the target vessel