Morphological Parameters of In-stent RESTenosis Assessed and Identified by OCT

Overview

The statistical risk of intrastent stenosis has fallen considerably with the emergence of latest generation coated stents (drug-eluting stents: DES). The number and clinical lifespan of stents implanted over the last twenty-five years, however, explain the fact that restenosis remains a not unusual clinical problem which is expressed as a recurrence of angina or of an acute coronary syndrome (ACS). The mechanisms involved in this restenosis are multifactorial in nature and differ depending on the type of stent and the time since the restenosis occurred. In symptomatic stent restenosis (angina or acute coronary syndrome), a further angioplasty is usually required, occasionally on an emergency basis. Coronary angiography is often not capable of explaining the mechanical causes of this complication. Optical coherence tomography (OCT), a high-resolution endocoronary imaging technique can assist in the understanding of the mechanism of restenosis and guide treatment. OCT during angiography provides a detailed analysis of the stents and potential complications: the presence of neoatherosclerosis with or without plaque rupture, intimal hyperplasia, stent under-deployment, stent fracture and distal or proximal progression of the atherosclerosis. The investigators propose a prospective, multicentre study of all cases of intrastent restenosis, examined by angiography, causing clinical features involving stable angina and acute coronary syndrome. The coronary artery involved will be routinely studied by OCT for a mechanical cause of the intrastent restenosis. The routine use of intrastent OCT may assist in the understanding of causes of restenosis and in the decision on appropriate treatment. There are several possible treatments for restenosis, including balloon angioplasty, coated balloon angioplasty, stenting or aorto-coronary bypass graft surgery.

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).