This study aims at evaluating the relationship between peripheral artery plaque characteristics evaluated by ultrasound and coronary culprit lesion characteristics evaluated by OCT in ACS patients.

Patients with acute coronary syndrome (ACS) who underwent percutaneous coronary intervention (PCI) and optical coherence tomography (OCT) are included in this study. Two skillful echocardiographers will evaluate peripheral artery plaque characteristics by ultrasound.Ultrasound parameters of peripheral artery will be compared among patients with different coronary culprit lesion characteristics, such as plaque rupture and plaque erosion.

Inclusion Criteria:

• Diagnosed as ACS underwent coronary angiography and OCT examination
• Agreed to accept peripheral artery ultrasound examination

Exclusion Criteria:

• In-stent restenosis, coronary dissection, coronary spam, thrombus
• left main artery disease
• Age>85 years old
• Cardiogenic shock or stroke admission
• Severe hepatic or renal dysfunction
• Poor quality of OCT image or massive thrombus

ACS patients