This study will be a prospective, randomized clinical trial to compare standard practice guided by usual care testing to CT-FFR-guided management in patients with in-stent restenosis.

This trial will randomize 294 patients with in-stent restenosis to receive either CT-FFR or routine clinical assessment. In all subjects, the investigators will review all diagnostic test results and determine a treatment strategy. The primary end point will be 12-month Major Adverse Coronary Event (MACE) rates, defined as all cause death, non-fatal myocardial infarction (MI), ischemia-driven target vessel revascularization (TVR). Secondary end points will include total medical costs, and quality of life (QOL), medical radiation exposure, etc. We will test noninferiority of current FFR-guided strategy compared with standard care strategy.

Inclusion Criteria:

• (1) >18 years old;
• (2) ability to provide informed consent;
• (3) previous PCI who underwent CCTA and have at least 1 lesion with a percent diameter in-stent stenosis between 30% and 90% in a coronary artery with a ≥2.25 mm reference vessel diameter by visual assessment;
• (4) accepted further clinically indicated coronary testing, coronary arteriography, or FFR, or IVUS, or PCI, etc.

Exclusion Criteria:

• (1) Prior coronary artery bypass surgery (CABG), heart valve surgery, cardiac pacemaker, or implanted cardiac defibrillator;
• (2) Target vascular stents were evaluated for implantation within one month;
• (3) unstable clinical conditions including acute chest pain, cardiogenic shock, congestive heart failure (NYHA grade III or IV), unstable blood pressure (systolic blood pressure < 90mmHg) or acute pulmonary edema;
• (4) Acute myocardial infarction occurred within 7 days before enrollment, and left ventricular ejection fraction ≤40%;
• (5) Other severe cases are not suitable for clinical trials including complex congenital heart disease, sick sinus syndrome, long QT syndrome, severe arrhythmia, tachycardia, severe asthma, severe or very severe chronic obstructive pulmonary disease (COPD) and severe chronic renal damage;
• (6) Contraindication to beta blockers, nitroglycerin, adenosine, or allergy to iodine contrast agents;
• (7) Pregnancy or pregnancy status unknown;
• (8) Life expectancy <1 years;
• (9)Repeated enrollment;
• (10) Any other factors that other researchers consider not suitable for inclusion or completion of this study.