Natural history of optical coherence tomography-detected non-flow-limiting edge dissections following drug-eluting stent implantation

Optical coherence tomography (OCT) is a novel intravascular imaging modality, based on infrared light emission, that enables a high resolution arterial wall imaging, in the range of 10-20 microns. This feature of OCT allows the visualization of specific components of the atherosclerotic plaques. The aim of the present Expert Review Document is to address the methodology, terminology and clinical applications of OCT for qualitative and quantitative assessment of coronary arteries and atherosclerosis.

New-generation coronary stents that release zotarolimus or everolimus have been shown to reduce the risk of restenosis. However, it is unclear whether there are differences in efficacy and safety between the two types of stents on the basis of prospectively adjudicated end points endorsed by the Food and Drug Administration. In this multicenter, noninferiority trial with minimal exclusion criteria, we randomly assigned 2292 patients to undergo treatment with coronary stents releasing either zotarolimus or everolimus. Twenty percent of patients were randomly selected for repeat angiography at 13 months. The primary end point was target-lesion failure, defined as a composite of death from cardiac causes, any myocardial infarction (not clearly attributable to a nontarget vessel), or clinically indicated target-lesion revascularization within 12 months. The secondary angiographic end point was the extent of in-stent stenosis at 13 months. At least one off-label criterion for stent placement was present in 66% of patients. The zotarolimus-eluting stent was noninferior to the everolimus-eluting stent with respect to the primary end point, which occurred in 8.2% and 8.3% of patients, respectively (P<0.001 for noninferiority). There were no significant between-group differences in the rate of death from cardiac causes, any myocardial infarction, or revascularization. The rate of stent thrombosis was 2.3% in the zotarolimus-stent group and 1.5% in the everolimus-stent group (P=0.17). The zotarolimus-eluting stent was also noninferior regarding the degree (+/-SD) of in-stent stenosis (21.65+/-14.42% for zotarolimus vs. 19.76+/-14.64% for everolimus, P=0.04 for noninferiority). In-stent late lumen loss was 0.27+/-0.43 mm in the zotarolimus-stent group versus 0.19+/-0.40 mm in the everolimus-stent group (P=0.08). There were no significant between-group differences in the rate of adverse events. At 13 months, the new-generation zotarolimus-eluting stent was found to be noninferior to the everolimus-eluting stent in a population of patients who had minimal exclusion criteria. (ClinicalTrials.gov number, NCT00617084.) 2010 Massachusetts Medical Society

Restenosis is a reparative response to arterial injury occurring with percutaneous coronary revascularization. However, the quantitative characteristics of the relation between vessel injury and the magnitude of restenotic response remain unknown. This study was thus performed to determine the relation between severity of vessel wall injury and the thickness of resulting neointimal proliferation in a porcine model of coronary restenosis. Twenty-six porcine coronary artery segments in 24 pigs were subjected to deep arterial injury with use of overexpanded, percutaneously delivered tantalum wire coils. The vessels were studied microscopically 4 weeks after coil implantation to measure the relation between the extent of injury and the resulting neointimal thickness. For each wire site, a histopathologic score proportional to injury depth and the neointimal thicknesses at that site were determined. Mean injury scores were compared with both mean neointimal thickness and planimetry-derived area percent lumen stenosis. The severity of vessel injury strongly correlated with neointimal thickness and percent diameter stenosis (p less than 0.001). Neointimal proliferation resulting from a given wire was related to injury severity in adjacent wires, suggesting an interaction among effects at injured sites. If the results in this model apply to human coronary arteries, restenosis may depend on the degree of vessel injury sustained during angioplasty.