All patients who have received GENOUS stent implantation at Queen Mary Hospital for treatment of ischemic heart disease are eligible for this study. Those with clinical indications to undergo restudy coronary angiogram or staged procedure PCI will be primarily recruited into this study.

Optical coherence tomography (OCT) will be performed early after stent implantation to evaluate vascular healing response and neointimal coverage.

The GENOUS Stent is a bio-engineered 316L stainless steel coronary stent with a biocompatible circumferential coating of anti-CD34 antibody, and will bind to and therefore capture the circulatory endothelial progenitor cells (EPC) which have CD34 antigen on the surface. Immobilization of EPCs on the stent surface will encourage differentiation and proliferation of the EPCs into endothelial and neointimal layer. This stent has been used extensively in 180 patients at Queen Mary Hospital with critical coronary stenosis.

Animal model has demonstrated that a functional endothelial layer could be formed as soon as 24 to 48 hours after GENOUS stent implantation (1). The HEALING-FIM registry has shown that GENOUS stent is clinically safe and effective in the treatment of coronary stenosis (2). Recent reports have further confirmed its efficacy in patients with acute coronary syndrome requiring urgent revascularization (3,4).

Intracoronary frequency domain optical coherence tomography (FD-OCT) is a simple catheter-based imaging technique using optic fibre to achieve very detailed assessment (resolution down to 10 microns) of the stents, in terms of stent apposition, early neointimal coverage (enhanced endothelialization) and late stent neointimal growth (restenosis). It is performed as part of the routine cardiac catheterization procedure and provides high-resolution cross sectional images of the coronary arteries. OCT has been shown to be safe in clinical practice (5). The LightLab C7XR OCT System (Frequency Domain OCT) is a commercially available product with CE Mark and FDA approval, and is being used in our EGO Study. The Dragonfly OCT catheter used is a non-occlusive optic fibre which is extremely small and flexible, and will pose absolutely no additional risk to the patient under treatment, other than those inherent risks of a standard angioplasty procedure.

Despite data in animal model showed a fast and complete endothelization, there is no study to verify and investigate on such healing benefits in human patients. Therefore, if endothelization and early neointimal healing benefits of the GENOUS stent can be evaluated by a reliable imaging technique, further studies can be carried out to extend the benefits of the EPC capturing capacity.

Inclusion Criteria:-

1. Patients aged 18-85 years old who received GENOUS stent treatment for ischemic coronary disease, and
2. Clinically indicated for a follow-up coronary angiogram or repeated (staged) coronary interventions within 3 months.

Exclusion Criteria:-

Patients who refuse to consent to coronary angiogram or coronary angioplasty.