All stented coronary artery patients hospitalised for stable angina or an ACS requiring a further coronary angiogram (regardless of time since implantation or type of the initial stent) identified to have intrastent restenosis during coronary angiography will be included after being informed and obtaining their informed written consent.

• For cases of stable angina the OCT the will be performed immediately with insertion of the probe distal to the area being studied and then automatic retraction of the fibre during injection of the contrast medium.
• For ACS, the OCT will be performed immediately or on a deferred basis at the discretion of the operator.
• For critical lesions which prevent the OCT fibre passing across the lesion, "soft" predilatation with a 2 mm or smaller balloon is permitted.
• Practical conduct of the OCT:
• Pullback at baseline state and analysis of the stent with a 5 mm margin proximal and distal to the lesion.
• OCT analysis: under-deployment of the stent (expansion < 80% of the reference mean surface area), neoatherosclerosis with or without rupture, homogeneous or non-homogeneous hyperplasia, stent fracture and proximal or distal progression of the atherosclerosis.
• Final pullback in cases of a new angioplasty (balloon angioplasty, angioplasty with a coated balloon or stenting).
• The OCT investigations will be anonymised and registered in their original format with a view to centralised reading (Corelab ISIT, UMR 6284-CNRS, Clermont-Ferrand University).
• The angiography records will be submitted for reading by a panel blinded to the OCT for the purposes of demonstrating the added value of OCT in the fine details of diagnosis and the impact of a treatment decision. The angiograms will be reviewed in a centralised analytical laboratory, which will re-read the procedures blind.
• Patients will be followed up via telephone contact or visit one year after inclusion into the study to record any complications which have developed (possible myocardial infarction, reason, any new revascularisation of the target lesion or another artery and reason for this, any deaths and their causes).