In a cohort of patients referred to coronary computed tomography angiography (CCTA), the investigators aim:

1. To describe the natural history of the coronary atherosclerotic plaque development and progression or regression, as well as the plaque characterization and phenotypes over time by CCTA among deferred coronary lesions
2. To explore the precursors of plaques leading to acute coronary syndrome (ACS) or chronic coronary syndrome (CCS) in deferred coronary lesions
3. To investigate prognostic implication of qualitative and quantitative plaque analysis of stenosis and plaque features, disease patterns, hemodynamic parameters, and fat metrics on CCTA along with physiologic assessment
4. To investigate the effects of different treatment strategies according to stenosis and plaque features, fat metrics on CCTA along with physiologic assessments.

Invasive physiologic indices such as fractional flow reserve (FFR) are used to define ischemia-causing stenosis and guide percutaneous coronary intervention (PCI) in the clinical practice. FFR-guided PCI has been proven to improve clinical outcomes, however, a substantial proportion of patients continue to experience clinical events. The ISCHEMIA trial showed that invasive therapy did not improve prognosis in patients with moderate to severe ischemia compared to optimal medical therapy. Besides, a recent study implied that even in vessels with FFR>0.80, those have lesions with high-risk plaque characteristics (HRPC) demonstrated worse clinical outcomes. This might be not unexpected since previous evidence from postmortem studies demonstrated that unstable atherosclerotic plaques are prone to rupture and trigger adverse cardiovascular events.

In recent years, advances in imaging analysis made it possible to conduct novel measurements such as pericoronary inflammation or epicardial fat metrics and lesion-specific or vessel-specific hemodynamic parameters derived from CCTA (such as fractional flow reserve by CCTA [CT-FFR]) as well as the coronary disease patterns defined by physiologic distribution (predominant focal versus diffuse disease defined by CCTA derived pullback pressure gradient index) and local severity (presence versus absence of major gradient defined by CCTA-derived FFR gradient per unit length [dCT-FFR/ds]) of coronary atherosclerosis.

However, the relationship of these parameters and the combination of these indices on clinical outcomes has not been fully understood. Furthermore, though it has been known that high-risk plaques are related with worse outcomes even no significant blood flow impairment induced, best treatment strategy for these lesions remains unclear.

In this regard, the aims of this study are multiple, all the treatment strategies are at the discretion of the physicians in charge. For patients without further invasive angiography performed after CCTA or deferred for revascularization after invasive angiography with/without physiology or imaging assessments, the investigators will investigate coronary atherosclerotic plaque development and progression or regression, as well as the plaque characterization and phenotypes over time by CCTA, and to explore the precursors of plaques leading to acute coronary syndrome (ACS) or chronic coronary syndrome (CCS); for those with received revascularization, the investigators will investigate the prognostic value of CCTA based comprehensive analysis of coronary in combination with physiologic assessment. In all patients, the effects of different treatment strategies according to stenosis and plaque features, fat metrics as well as physiologic assessments will be investigated.

CHART is a study group called Chinese Non-invasive Cardiovascular Imaging and Physiology Study Group, the current study will be conducted by CHART and by invitation in multiple Chinese centers.

Inclusion Criteria:

• Patients with an indication for CCTA.
• Qualified patients who have signed a written informed consent form.

Exclusion Criteria:

• Left ventricular ejection fraction < 35%
• Acute ST-elevation myocardial infarction within 72 hours or previous coronary artery bypass graft surgery
• Abnormal epicardial coronary flow (TIMI flow < 3)
• Planned coronary artery bypass graft surgery after diagnostic angiography
• Poor quality of CCTA or other reasons by core lab that are unsuitable for plaque, physiological or fat analysis
• Patients with a stent in the target vessel

Patients with an indication for CCTA.