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Background: Endothelial progenitor cells (EPC) are involved in neovascularization and endothelial integrity. They might be protective in atherosclerosis. Optical coherence tomography (OCT) is a precise intracoronary imaging modality that allows assessment of subintimal plaque development. We evaluated the influence of EPC on coronary plaque burden in stable disease and implemented a novel computational plaque analysis algorithm using OCT., Methods: Forty-three patients (69.8% males, 69.6 ± 7.7 years) were investigated by OCT during re-angiography 6 months after elective stent implantation. Different subpopulations of EPCs were identified by flow cytometry according to their co-expression of antigens (CD34+, CD133+, kinase domain receptor, KDR+). An algorithm was applied to calculate the underlying total plaque burden of the stented segments from OCT images. Plaque morphology was assessed according to international consensus in OCT imaging., Results: A cumulative sub-strut plaque volume of 10.87 ± 12.7 mm 3 and a sub-stent plaque area of 16.23 ± 17.0 mm 2 were found within the stented vessel segments with no significant differences between different stent types. All EPC subpopulations (mean of EPC levels: CD34+/CD133+: 2.66 ± 2.0%; CD34+/KDR+: 7.50 ± 5.0%; CD34+/CD133+/KDR+: 1.12 ± 1.0%) inversely correlated with the identified underlying total plaque volume and plaque area (p ≤ 0.012)., Conclusions: This novel analysis algorithm allows for the first time comprehensive quantification of coronary plaque burden by OCT and illustration as spread out vessel charts. Increased EPC levels are associated with less sub-stent coronary plaque burden which adds to previous findings of their protective role in atherosclerosis.

One of the main limitations of percutaneous coronary interventions is the restenosis, occurring in small-diameter arteries, and efforts are high to find improved intracoronary devices to prevent in-stent-restenosis. Aim of this study was to produce a new in vitro test platform for restenosis research, suitable for long-term cell proliferation and migration studies in stented vessels. Fresh segments of porcine coronary arteries were obtained for decellularization and were then reseeded with human coronary artery endothelial (HCAEC) and human coronary artery smooth muscle cells (HCASMC). Subsequently, bare metal stents (BMS) and drug eluting stents (DES), respectively, were implanted and the segments were reseeded with HCAEC and HCASMC for up to three months. The stented segments were examined at time zero and after 2, 4, 6, 8 and 12 weeks by histochemical and immunohistochemical characterization and the reseeded areas before and after stent implantation were measured. We have found that cells formed multiple layers after three months, and the detection with both CD31 and a-smooth muscle actin specific antibodies showed that HCAEC and HCASMC are adherent and growing in several layers. Furthermore, we could show a significantly smaller proliferation area in DES (70% ± 3.5%), compared to BMS (17% ± 2.3%). These data are similar to animal and human studies. Therefore, this vessel model might appear as an initial benchmark for testing new anti-proliferative endovascular therapies and consequently helps to reduce animal experiments in this research area.

Background: In this randomized trial, strut coverage and neointimal proliferation of a therapy of bare metal stents (BMSs) postdilated with the paclitaxel drug-eluting balloon (DEB) was compared with everolimus drug-eluting stents (DESs) at 6-month follow-up using optical coherence tomography. We hypothesized sufficient stent coverage at follow-up., Methods and Results: A total of 105 lesions in 90 patients were treated with either XIENCE V DES (n=51) or BMS postdilated with the SeQuent Please DEB (n=54). At follow-up, comparable results on the primary optical coherence tomography end point (percentage uncovered struts 5.64±9.65% in BMS+DEB versus 4.93±9.29% in DES; P=0.366) were found. Thus, BMS+DEB achieved the prespecified noninferiority margin of 5% uncovered struts versus DES (difference between treatment means, 0.71%; one-sided upper 95% confidence interval, 4.14%; noninferiority P=0.04). Optical coherence tomography analysis showed significantly more global neointimal proliferation in the BMS+DEB group (15.7±7.8 versus 11.0±5.2 mm(3) proliferation volume/cm stent length; P=0.002). No significant focal in-stent stenosis analyzed with angiography (percentage diameter stenosis at follow-up, 22.8±11.9 versus 16.9±10.4; P=0.014) and optical coherence tomography (peak local area stenosis, 39.5±13.8% versus 36.8±15.6%; P=0.409) was found., Conclusions: Good stent strut coverage of >94% was found in both therapy groups. Despite greater suppression of global neointimal growth in DES, both DES and BMS+DEB effectively prevented clinically relevant focal restenosis at 6-month follow-up., Clinical Trial Registration Url: http://www.clinicaltrials.gov. Unique identifier: NCT01056744., (© 2014 American Heart Association, Inc.)

Background: Safety concerns regarding use of drug-eluting stent systems (DES) are related mostly to late stent thrombosis, which is facilitated by incomplete stent endothelial coverage. Specific information about time course and amount of endothelial strut coverage of different DES is required, in order to further refine the concept of antiplatelet therapy after DES implantation. Optical coherence tomography (OCT) is emerging as a new gold standard for endovascular imaging of stents, atherosclerosis progression, vulnerable plaque, and neointimal proliferation. The aim of this study is a comparative evaluation using OCT of the XIENCE V everolimus-eluting stent (Abbot Vascular, Santa Clara, CA, USA) on one hand, and the bare metal stent Coroflex Blue postdilated with the paclitaxel-eluting balloon Sequent Please (both from B Braun Melsungen AG, Melsungen, Germany) on the other hand, with respect to endothelial coverage and neointimal proliferation., Methods: Eighty patients scheduled for elective percutaneous coronary intervention (PCI) of a native coronary stenosis suitable for DES implantation and OCT imaging are scheduled to be openly randomised 1:1 to either XIENCE or Coroflex Blue/Sequent Please. The study is conducted prospectively at a university high-volume PCI centre with OCT expertise. Angiographic follow-up and time-domain OCT imaging with motorised pull-back at 1 mm/s are planned six months after study stent implantation in all patients. OCT endpoints are: (1) endothelial coverage, expressed as % of struts without coverage and % of stent length containing non-covered struts, and respectively (2) neointimal proliferation, given as % neointimal volumetric proliferation within the whole stent and also as peak focal % neointimal area proliferation. The study is not powered for clinical endpoints, which are: subacute or late stent thrombosis and need for revascularisation of the stent segment. Given the high number of measurements (15 cross-section images / 1 mm stent length), OCT endpoints are likely to reach significance at the level p <0.05, if the drop-out rate in follow-up does not exceed 20%., Current Status: The study is currently on-going and its termination is scheduled for February 2010. (ClinicalTrials.gov identifier: NCT01056744).

Many different approaches have been evaluated to prevent restenosis in stents after vascular implantation. Currently, drug-eluting stents are extremely promising in suppressing neointimal hyperplasia. Various animal studies and randomized trials in humans have shown excellent results in terms of safety and efficacy during intermediate-term follow-up. This article will give an overview of experimental and clinical data of the different agents in published and ongoing trials.