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Provisional stenting is considered the gold standard approach for most bifurcation lesions, but the benefit of routine side branch (SB) strut dilatation has not been fully elucidated. A benchtop model was used to determine the benefits of routine side branch (SB) dilatation techniques on strut apposition, acute thrombogenicity, and flow disruption. Three different provisional bifurcation techniques were compared: no SB dilatation "keep it open" method (KIO), sequential balloon dilatation (SBD), and kissing balloon inflation (KBI). Stents were deployed in a silicon bifurcation model and perfused with blood at a flow rate of 200 ml/min for 60 min. Optical coherence tomography (OCT) pullbacks were obtained before and after flow perfusion to conduct strut analysis and acute thrombus measurement respectively. Computational fluid dynamics (CFD) models were created using OCT pullbacks and simulated based on experimental conditions to analyze flow disruption. The strut analysis showed that KBI had the lowest percentage of floating (10.6 ± 2.3%) (p = 0.0004) and malapposed (41.2 ± 8.5%) struts (p = 0.59), followed by SBD and then KIO. This correlated to KBI having the lowest amount of thrombus formed at the SB, followed by SBD, with KIO being the most thrombogenic (KBI: 0.84 ± 0.22mm 2 , SBD: 1.17 ± 0.25mm 2 , KIO: 1.31 ± 0.36mm 2 , p = 0.18). CFD models also predicted a similar trend, with KBI having the lowest amount of area of high shear rate as well as flow recirculation. Based on this benchtop model, SB intervention strategies demonstrated a reduction in number of struts and resulting thrombogenicity at the bifurcation ostia. Graphical abstract., (© 2021. Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Percutaneous coronary interventions on complex bifurcation lesions may require implantation of two stents to appropriately treat diffuse side-branch (SB) disease. Comparisons among different bifurcation stenting techniques are continuously attempted by various study designs (bench tests, computer simulations, clinical studies). Among different techniques, double kissing crush (DKC) represents the last evolution for "crushing" while T and small Protrusion (TAP) represents the evolution of "T stenting". Both techniques are actually gaining popularity, but head-to-head comparisons are lacking., Methods and Results: Two last generation drug-eluting stents (Synergy™, Boston Scientific, MA, USA and Ultimaster™,Terumo Corp., Japan) were implanted in left main bifurcation bench models using TAP (n = 6 sets) and DKC (n = 6 sets) techniques. A peristaltic pump with fresh porcine blood was used to perfuse the blood through the silicone model at a flow rate of 200 ml/min for 4 min. Optical coherence tomography (OCT) was used to assess stent struts geometry and thrombus formation. SB cross sectional area as well as SB obstruction did not significantly differ between the two techniques. Numerical (but not statistically significant) differences were found in terms of malapposed struts (fewer with TAP) and floating struts (fewer with DKC). Thrombus formation after blood perfusion was similar between TAP and DKC technique (1.53 ± 1.12 vs. 1.20 ± 1.01 mm 2 , p = 0.6)., Conclusion: The result of the present in-vitro study shows the absence of significant difference between TAP and DKC in terms of stent struts apposition and acute thrombus formation potential. Despite the completely different technical steps required, both techniques have similar performance according to such articulated pre-clinical evaluation. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT?: Due to its limited complexity, T and Protrusion (TAP) technique is considered the to-go technique for bifurcation lesions with good long-term results. Recently, double kissing crush (DKC) technique has been gaining popularity and demonstrated promising results in randomized clinical trials. WHAT DOES THIS STUDY ADD?: This in-vitro bench test study provides a unique detailed OCT comparison and local hemodynamic environment analysis of the two techniques. HOW MIGHT THIS IMPACT ON CLINICAL PRACTICE?: New insights of acute thrombogenicity and computational flow model simulation may guide percutaneous therapeutic strategies of bifurcation lesions., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Interventions in bifurcation lesions often requires aggressive overexpansion of stent diameter in the setting of long tapering vessel segment. Overhanging struts in front of the side branch (SB) ostium are thought to act as a focal point for thrombi formation and consequently possible stent thrombosis. This study aimed to evaluate the overexpansion capabilities and thrombogenicity at the SB ostia after implantation of four latest generation drug-eluting stents (DES) in an in-vitro bifurcation model. Four clinically available modern DES were utilized: one bifurcation dedicated DES (Bioss LIM C) and three conventional DES (Ultimaster, Xience Sierra, Biomime). All devices were implanted in bifurcation models with proximal optimization ensuring expansion before perfusing with porcine blood. Optical coherence tomography (OCT), immunofluorescence (IF) and scanning electron microscope analysis were done to determine thrombogenicity and polymer coating integrity at the over-expanded part of the stents. Computational fluid dynamics (CFD) was performed to study the flow disruption. OCT (p = 0.113) and IF analysis (p = 0.007) demonstrated lowest thrombus area at SB ostia in bifurcation dedicated DES with favorable biomechanical properties compared to conventional DES. The bifurcated DES also resulted in reduced area of high shear rate and maximum shear rate in the CFD analysis. This study demonstrated numerical differences in terms of mechanical properties and acute thrombogenicity at SB ostia between tested devices.

Bioresorbable scaffolds (BRS) were introduced to overcome limitations of current metallic drug-eluting stents and poly-L-lactide (PLLA) has been used in the fabrication of BRS due to its biodegradability and biocompatibility. However, such polymers have weaker mechanical properties as compared to metals, limiting their use in BRS. We hypothesized that nanofillers can be used to enhance the mechanical properties considerably in PLLA. To this end, polymer-matrix composites consisting of PLLA reinforced with 5-20 wt% barium sulfate (BaSO 4 ) nanofillers as a potential BRS material was evaluated. Stearic-acid (SA) modified BaSO 4 nanofillers were used to examine the effect of functionalization. Rigid nanofillers improved the tensile modulus and strength of PLLA (60% and 110% respectively), while the use of SA-BaSO 4 caused a significant increase (~110%) in the elongation at break. Enhancement in mechanical properties is attributed to functionalization which decreased the agglomeration of the nanofillers and improved dispersion. The nanocomposites were also radiopaque. Finite element analysis (FEA) showed that scaffold fabricated from the novel nanocomposite material has improved scaffolding ability, specifically that the strut thickness could be decreased compared to the conventional PLLA scaffold. In conclusion, BaSO 4 /PLLA-based nanocomposites could potentially be used as materials for BRS with improved mechanical and radiopaque properties.

The progress and development of drug-coated balloons (DCBs) represents an emerging alternative treatment in peripheral and coronary artery diseases, particularly when a non-stent approach is necessary. Several studies and meta-analyses have evaluated the clinical outcomes of DCBs in different lesions and this review aims to compile the progress and updated clinical data of DCB strategy in both peripheral artery diseases (PAD) and coronary artery diseases (CAD). The review highlights that clinical data has encouraged the use of DCB for applications in PAD and in the treatment of coronary in-stent restenosis (ISR). The employment of DCB in side branch treatment of bifurcation lesions has been reported to be feasible and safe, with good angiographic and clinical outcome. The use of DCB for arteriovenous fistula and grafts stenoses is a promising strategy, but more clinical data is required to draw reliable conclusions. The limitations and impact of the current generation of DCBs will be discussed and the clinical development of newer generation of the device is also covered in this review., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Aims: The aim of this report was to examine the effect of underexpansion on stent thrombogenicity with an in vitro perfusion model., Methods and Results: Drug-eluting stent (DES) samples were partially underdeployed in silicone tubes and perfused with porcine blood containing 10% anticoagulant citrate dextrose solution for four minutes at a flow rate of 200 ml/min. Thrombus formation was evaluated and compared between the well-apposed and malapposed sections. The malapposed sections showed significantly more thrombus formation compared to the well-apposed sections (13.9 vs. 0.41 mm2, p<0.001)., Conclusions: Stent malapposition has a very direct impact on thrombus formation. Optimised stent implantation is required to minimise malapposition in DES and BVS to reduce thrombus formation.

Background: Bench models of coronary bifurcation lesions demonstrated that the proximal optimization technique (POT) expanded the stent and opened the side branch (SB). We investigated the role of POT guided by intravascular ultrasound on the main vessel (MV) stent expansion and SB fractional flow reserve (FFR) in patients with coronary bifurcation lesion., Methods and Results: In 40 patients with coronary bifurcation lesion, 120 intravascular ultrasound examinations of the MV were performed at baseline, after MV stenting, and POT followed by 95 FFR measurements of the SB. In the proximal stent segment, stent volume index and minimum stent area were larger after POT versus MV stenting (9.2±3.4 versus 7.40±2.0 mm 3 /mm and 7.65±1.8 versus 6.38±1.7 mm 2 , respectively; P <0.01). In the bifurcation segment, minimum stent area was larger after POT versus MV stenting (6.45±2.1 versus 5.9±2.0 mm 2 , respectively; P <0.05). POT expanded the stent symmetrically. After POT, SB FFR was <0.75 in 12 patients (30%), which improved to >0.75 after SB dilation or SB stenting+final POT. SB FFR was significantly higher after POT+SB dilation or SB stenting+final POT versus after MV stenting and POT., Conclusions: This is the first study of POT guided by intravascular ultrasound in patients with coronary bifurcation lesion, demonstrating that POT symmetrically expanded the proximal and bifurcation segments of the stent. After POT, SB FFR was <0.75 in a third of patients, which improved to >0.75 after SB dilation or SB stenting+final POT., (© 2017 American Heart Association, Inc.)

Background: The long-term fate of Absorb bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, CA) struts jailing side branch ostia has not been clarified. We therefore evaluate serially (post-procedure and at 6 months, 1, 2, 3, and 5 years) the appearance and fate of jailed Absorb bioresorbable vascular scaffold struts., Methods and Results: We performed 3-dimensional optical coherence tomographic analysis of the ABSORB Cohort B trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions) up to 5 years using a novel, validated cut-plane analysis method. We included 29 patients with a total of 85 side branch ostia. From the 12 ostia which could be assessed in true serial fashion, 7 showed a pattern of initial decrease in the ostial area free from struts, followed by an increase in strut-free ostial area toward the end of the 5 years of follow-up. In a repeated-measures analysis with time as fixed variable and ostial area free from struts as dependent variable, we showed a numeric decrease in the estimated ostial area free from struts from 0.75 mm 2 (baseline) to 0.68 mm 2 (first follow-up visit at 6 months or 1 year) and 0.63 mm 2 (second follow-up visit at 2 or 3 years). However, from the second visit to the 5-year follow-up visit, there was a statistically significant increase from 0.63 to 0.89 mm 2 ( P =0.001). Struts overlying an ostium divided the ostium into compartments, and the number of these compartments decreased over time., Conclusions: This study showed that in most cases, the side branch ostial area free from struts initially decreased. However, with full scaffold bioresorption, the ostial area free from scaffold increased between 2 to 3 years and 5 years in the vast majority of patients., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00856856., (© 2017 American Heart Association, Inc.)

Background/purpose: Computational fluid dynamics (CFD) have been recently adopted in many fields of cardiovascular medicine and in interventional cardiology. Using CFD analysis we compared the use of different PCI procedures, with and without the utilization of a proximal optimization technique (POT), on a complex coronary artery bifurcation., Methods/materials: For the analysis, we considered a hypothetic model of a left anterior descending artery-diagonal Medina 1,1,1 bifurcation type with a diameter of the proximal main branch (MB) and the side branch (SB) set at 3.5mm and 2.5mm, respectively. The bifurcation angle has been set to 50°. For the stent simulation, we reconstructed a third-generation, ultra-thin strut everolimus-eluting stent (ORSIRO stent, Biotronik IC, Bulack, Switzerland)., Results: The Nano-crush and the modified T techniques seem able to restore the most physiologic fluid dynamic profile. Conversely, the DK-crush and the culotte demonstrated an intermediate and worst effect, respectively. The addition of a final POT resulted favorably for both Nano-crush and reverse modified T techniques, whereas a neutral and lack of significant effects have been observed for the DK-crush and culotte technique, respectively., Conclusion: Different double-stenting techniques (DST) have a different impact on coronary flow physiology. Both Nano-crush and modified T techniques achieved the most physiologic profile. The addition of a final POT appears to be a favourable step for both Nano-crush and modified T., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The DESolve® scaffold (Elixir Medical Corporation, Sunnyvale, California, USA) is manufactured from a poly-l-lactide based polymer and elutes an anti-proliferative, anti-inflammatory drug, Novolimus from a poly-l-lactide based topcoat mixture. The strut thickness is 150μm and the scaffold has platinum-iridium radiopaque markers at both ends. Radial support is available during the early time period to prevent recoil. The scaffold biodegrades within 1year (>90% reduction in molecular weight) and then completely bioresorbs within 2years. The DESolve® scaffold permits a wide range of expansion with a consequently reduced risk for strut fracture. Lumen and scaffold enlargement is observed within 3-6months in both preclinical and clinical studies potentially allowing for the scaffolded region to respond to vasoactive stimuli. The device has a unique property of self-correction observed in bench top studies, which in clinical practice has the potential to eliminate minor malapposition following deployment., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Background: Previously, we examined the difference in stent designs across different sizes for six widely used Drug Eluting Stents (DESs). Although stent post-dilatation to larger diameter is commonly done, typically in the setting of long tapering segment or left-main PCI, there is an increasing recognition that information with regard to the different stent model designs has a critical impact on overexpansion results. This study aims to provide an update on stent model designs for contemporary DES platforms as well as test overexpansion results under with oversized post-dilatation., Methods and Results: We studied 6 different contemporary commercially available DES platforms: Synergy, Xience Xpedition, Ultimaster, Orsiro, Resolute Onyx and Biomatrix Alpha. We investigated for each platform the difference in stent designs across different sizes and results obtained after post-expansion with larger balloon sizes. The stents were deployed at nominal diameter and subsequently over expanded using increasingly large post dilatation balloon sizes (4.0, 5.0 and 6.0mm at 14ATM). Light microscopy was used to measure the changes in stent geometry and lumen diameter after over-expansion. For each respective DES platform, the MLD observed after overexpansion of the largest stent size available with a 6.0mm balloon was 5.7mm for Synergy, 5.6mm for Xience, 5.2mm for Orsiro, 5.8mm for Ultimaster, 5.5mm for 4mm Onyx (5.9mm for the 5mm XL size) and 5.8mm for BioMatrix Chroma., Conclusion: This update presents valuable novel insights that may be helpful for careful selection of stent size for contemporary DES based on model designs. Such information is especially critical in left main bifurcation stenosis treatment where overexpansion to larger oversized diameter may be required to ensure full stent apposition., (Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.)

The coating material technology is important for the delivery of anti-proliferative drugs from the surface of drug-eluting balloons (DEBs), which are emerging as alternatives to drug-eluting stents (DES) in the field of interventional cardiology. Currently, several shortcomings limit their competition with DES, including low drug transfer efficiency to the arterial tissues and undesirable particulate generation from the coating matrix. In this review, we provide a survey of the materials used in existing DEBs, and discussed the mechanisms of actions of both the drugs and coating materials. The type of drug and the influence of the coating material characteristics on the drug uptake, distribution and retention in arterial tissues are described. We also summarize the novel coating excipients under development and provide our perspective on the possible use of nano-scale carriers to address the shortcomings of current coating technology. The scope of this review includes only materials that have been approved for biomedical applications or are generally recognized as safe (GRAS) for drug delivery., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Aims: This study aimed to compare the acute expansion behaviour of a polymer-based bioresorbable scaffold and a second-generation metallic DES platform in a realistic coronary artery lesion model. Experimental mechanical data with conventional methods have so far shown little difference between metallic stents and currently available polymer-based bioresorbable scaffolds (BRS). Nevertheless, differences in acute results have been observed in clinical studies comparing BRS directly with metallic DES platforms., Methods and Results: We examined the expansion behaviour of the bioresorbable vascular scaffold (3.0×18 mm Absorb BVS; Abbott Vascular, Santa Clara, CA, USA) and a metallic DES (3.0×18 mm XIENCE Prime; Abbott Vascular) after expansion at 37°C using identical coronary artery stenosis models (in total 12 experiments were performed). Device expansion was compared during balloon inflation and after deflation using microscopy to allow assessment of plaque recoil. Minimal lumen diameter (MLD) and minimal lumen area (MLA) and stent eccentricity were quantified from optical coherence tomography (OCT) imaging at nominal diameter and after post-dilation at 18 atm. The MLA in the models with BVS deployed was 4.92±0.17 mm² while in the metallic DES it was 5.40±0.13 mm2 (p=0.02) at nominal pressure (NP), and 5.41±0.20 and 6.07±0.25 mm2 (p=0.02), respectively, after expansion at 18 atm. Stent eccentricity index at the MLA was 0.71±0.02 in BVS compared to 0.81±0.02 in the metal stent at NP (p=0.004), and 0.73±0.03 compared to 0.75±0.02 at 18 atm (p=0.39)., Conclusions: Results obtained in this in vitro lesion model were comparable to the results in randomised clinical trials comparing BVS and XIENCE stents in vivo. Such models may be useful in future BRS developments to predict their acute response in vivo in eccentric lesions.

Aims: The aim of the study was to compare retrospectively the acute mechanical performance of the Absorb vs. DESolve scaffolds in terms of appropriate deployment with OCT., Methods and Results: Final post-deployment OCT pullbacks of consecutive patients treated with either Absorb or DESolve were reviewed. The following parameters were calculated and compared: mean and minimal lumen area (MLA), residual in-scaffold area stenosis (RAS), incomplete strut apposition (ISA), tissue prolapse area, eccentricity index, asymmetry index, strut fracture and edge dissection. A total of 72 patients were included. The Absorb group consisted of 35 patients treated with 63 Absorb scaffolds and was compared to a well-matched group of 37 patients treated with 50 DESolve scaffolds. Baseline characteristics did not differ significantly between the two groups. Procedural characteristics were different with respect to maximal balloon inflation pressure (Absorb vs. DESolve: 21.5±0.4 atm vs. 16.8±3.8 atm, p<0.01) and mean NC balloon diameter used for post-dilatation (Absorb vs. DESolve 3.3±0.4 mm vs. 3.5±0.4 mm, p<0.01). OCT analysis showed similar MLA (Absorb vs. DESolve: 5.8±1.9 mm2 vs. 6.1±2.6 mm2, p=0.43) and mean luminal area (Absorb vs. DESolve: 7.1±2.2 mm2 vs. 7.2±1.9 mm2, p=0.77). The mean eccentricity index was 0.85±0.05 with Absorb and 0.80±0.05 with DESolve, p<0.01. There was no difference in the incidence of overall ISA. A smaller prolapse area was found with Absorb (Absorb vs. DESolve 1.0±1.1 mm2 vs. 3.6±6.2 mm², p<0.01)., Conclusions: The two scaffolds showed similar MLA while there was a trend towards a lower RAS and a larger maximum and minimum scaffold diameter with DESolve. The DESolve scaffold was more eccentric as compared to the Absorb. These results might be related to the DESolve's unique expansion properties or they may reflect baseline and procedural differences which cannot be excluded in a retrospective study. Randomised studies are needed to address this aspect.

Aims: Previous studies have associated issues such as incomplete stent apposition with delayed healing and adverse events (stent thrombosis). The aim of this study was to evaluate the impact of strut apposition and stent type on the progression of stent strut coverage., Methods and Results: We evaluated in vivo in porcine models the follow-up response and coverage characteristics of well-apposed and malapposed segments of drug-eluting stents (DES) (CYPHER, PROMUS Element and Orsiro) and the Absorb bioresorbable vascular scaffold (BVS) by optical coherence tomography (OCT) sequentially, at baseline, and at one week and four weeks of follow-up. Supporting results were provided by histological analysis performed at four-week follow-up and computer simulation describing the shear characteristics around apposed and non-apposed struts. A total of 325 cross-sections containing 3,166 struts were analysed. The extent of malapposition decreased over time as a result of neointimal healing (from 7.1% at baseline to 0% at four weeks; p=0.03). At one week, 13.6% of struts in well-apposed segments were still uncovered versus 19.2% of struts in malapposed cross-sections and 77.8% of NASB struts (p<0.01). At four-week follow-up, 3.1% of struts were uncovered in well-apposed cross-sections vs. 1.6% in malapposed cross-sections and 35.7% of NASB struts (p<0.01). A comparison of the apposed segments revealed that the thin-strut Orsiro had only 1.3% of uncovered struts at one week while PROMUS Element, CYPHER and BVS had 6.6%, 48.4% and 16.2% of struts still uncovered, respectively., Conclusions: This study shows that early coverage is influenced by stent apposition as well as platform strut characteristics (stent type). At four weeks, NASB struts remained a focus of delayed endothelialisation.

Focal ultrashort balloons are essential tools for lesion preparation and final stent expansion. However, they may cause a major distortion of the adjacent segments. Here we report a case with a stent deformation emphasizing the importance of utilizing intravascular imaging techniques for optimal interventions., (Copyright © 2015 Elsevier Inc. All rights reserved.)

The treatment of obstructive coronary artery disease has been revolutionised by the advent of drug-eluting stent therapy. However, concerns remain about complications late after stent implantation including late stent thrombosis, hypersensitivity reactions and neoatherosclerosis. In this respect, the introduction of fully bioresorbable stents (BRS)--which resorb over time and leave the arterial wall free of any metal constraints--represents a potentially important disruptive technology. However, although the concept is intuitively attractive, a thorough understanding of the histopathological changes seen after BRS implantation and an appreciation of comparative changes versus existing metal stent technologies are vital to guide BRS clinical usage. In this respect, translational investigation of polymer chemistry, biomedical engineering, as well as in vitro and in vivo testing in animal models is an important undertaking. This article will review the pathological aspects of BRS implantation with a focus on acute and chronic vascular reactions derived from preclinical animal studies, including insights from in vivo imaging. Finally, potential future directions of this novel therapeutic approach will be discussed.

Despite the tremendous developments that have been made in the field of interventional cardiology over the past few decades, the percutaneous treatment of left main (LM) bifurcation still remains challenging. The provisional one-stent approach for LM bifurcation showed more favourable outcomes compared to the double-stenting technique. Consequently, it has been the preferred strategy in the majority of LM bifurcation stenosis. However, due to the large myocardial burden of the side branch, the risk of haemodynamic collapse after main vessel stenting has always existed. To reduce the risk of side branch occlusion and for proper selection of this strategy, it is acknowledged that meticulously performed IVUS evaluation of the side branch ostium is helpful. A fractional flow reserve measurement of the angiographically jailed side branch could also lead to the avoidance of an unnecessary complex intervention. However, as the overall data were derived from observational studies, further larger randomised trials would be necessary to assess the optimal provisional one-stent strategy for LM bifurcation.

Objectives: The aim of this study was to compare the acute performance of the PLLA ABSORB bioresorbable vascular scaffold (BVS) (Abbott Vascular, Santa Clara, California) with second-generation metal drug-eluting stents (DES) in complex coronary artery lesions., Background: Thick polymer-based BVS have different mechanical properties than thin second-generation DES. Data on the acute performance of BVS are limited to simple coronary lesions treated in trials with strict inclusion criteria., Methods: Fifty complex coronary lesions (all type American College of Cardiology/American Heart Association B2-C) treated with a BVS undergoing a final optical coherence tomography (OCT) examination were compared with an equal number of matched lesions treated with second-generation DES. The following stent performance indexes were assessed with OCT: mean and minimal area, residual area stenosis (RAS), incomplete strut apposition (ISA), tissue prolapse, eccentricity index, symmetry index, strut fracture, and edge dissection., Results: One hundred lesions from 73 patients were analyzed. A higher balloon diameter/reference vessel diameter ratio was used for predilation in the BVS group (p < 0.01). Most of the BVS and DES were post-dilated with short noncompliant (NC) balloons of similar diameter. OCT showed in the BVS group a higher tissue prolapse area (p = 0.08) and greater incidence of ISA at the proximal edge (p = 0.04) with no difference in the overall ISA. The RAS was 20.2% in the BVS group and 21.7% in the DES group (p = 0.32). There was no difference in the eccentricity index. The minimal and mean lumen areas were similar in the 2 groups. Two cases of strut fractures occurred after the BVS, whereas none was observed in the DES., Conclusions: Based on OCT, the BVS showed similar post-procedure area stenosis, minimal lumen area, and eccentricity index as second-generation DES. The different approach for lesion preparation and routine use of OCT guidance during BVS expansion may have contributed to these results., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Lack of re-endothelialization and neointimal coverage on stent struts has been put forward as the main underlying mechanism leading to late stent thrombosis. Incomplete stent apposition (ISA) has been observed frequently in patients with very late stent thrombosis after drug eluting stent implantation, suggesting a role of ISA in the pathogenesis of this adverse event. The aim of this study was to evaluate the impact of different degrees of ISA severity on abnormal shear rate and healing response with coverage, because of its potential implications for stent optimization in clinical practice., Methods and Results: We characterized flow profile and shear distribution in different cases of ISA with increasing strut-wall detachment distance (ranging from 100 to 500 μm). Protruding strut and strut malapposed with moderate detachment (ISA detachment distance <100 μm) have minimal disturbance to blood flow as compared with floating strut that has more significant ISA distance. In vivo impact on strut coverage was assessed retrospectively using optical coherence tomography evaluation on 72 stents (48 patients) sequentially at baseline and after 6-month follow-up. Analysis of coverage revealed an important impact of baseline strut-wall ISA distance on the risk of incomplete strut coverage at follow-up. Malapposed segments with an ISA detachment <100 μm at baseline showed complete strut coverage at follow-up, whereas segments with a maximal ISA detachment distance of 100 to 300 μm and >300 μm had 6.1% and 15.7% of their struts still uncovered at follow-up, respectively (P<0.001)., Conclusions: Flow disturbances and risk of delayed strut coverage both increase with ISA detachment distance. Insights from this study are important for understanding malapposition as a quantitative, rather than binary phenomenon (present or absent) and to define the threshold of ISA detachment that might benefit from optimization during stent implantation.

Aims: Left main stenting is increasingly performed and often involves deployment of a single stent across vessels with marked disparity in diameters. Knowing stent expansion capacity is critical to ensure adequate strut apposition after post-dilatation of the stent has been performed. Coronary stents are usually manufactured in only two or three different model designs with each design having a different maximal expansion capacity. Information about the different workhorse designs and their maximal achievable diameter is not commonly provided by manufacturers but, in the absence of this critically important information, stents implanted in segments with major changes in vessel diameter have the potential to become grossly overstretched and to remain incompletely apposed., Methods and Results: We examined the differences in workhorse designs of six commercially available drug-eluting stents (DES): the PROMUS Element, Taxus Liberté, XIENCE Prime, Resolute Integrity, BioMatrix Flex and Cypher Select stents. Using micro-computed tomography, we tested oversizing capabilities above nominal pressures for the different workhorse designs of the six DES using 4.0, 5.0 and 6.0 mm post-dilatation balloons inflated to 14 atmospheres. MLD could be increased significantly in all stents, only restricted by workhorse design limitations. Minimal inner lumen diameter (MLD) achieved after two successive 6.0 mm post-dilatations of the largest design (4.0 mm stent) was 5.7 mm for the Element, 5.6 mm for the XIENCE Prime, 6.0 mm for the Taxus, 5.4 mm for the Resolute Integrity, 5.9 mm for the BioMatrix and 5.8 mm for the Cypher stent. Significant deformations were observed during stent oversizing with large changes in terms of cell opening and crowns expansion. These are affected by design structure and reveal important differences among all stents tested. Such extensive deformations may alter the functional ability of an individual stent to scaffold a lesion and prevent restenosis., Conclusions: Stent selection based on stent model design may be critical, particularly for treatment of large artery and left main bifurcations where overexpansion is normally required to optimise results and ensure full expansion of the stent.

Background: Percutaneous coronary intervention of complex true bifurcation lesions often fails to ensure continuous stent coverage and strut apposition in both the side branch and main vessel. Struts left unopposed floating in the lumen disturb blood flow and are increasingly recognized as increasing the risk of stent thrombosis., Methods and Results: In this study, we compared the results of different bifurcation treatment strategies: Crush (n=5); Culotte (n=3); T-/T with Protrusion (TAP) (n=4) using drug-eluting stents deployed in-vitro in representative coronary bifurcation models. After final kissing balloon post-dilatation, the rate of malapposition within the bifurcation quantified from micro-computed tomography scanning was on average 41.5 ± 8.2% with the Crush technique, reduced to respectively 31.4 ± 5.2% with Culotte and 36.7 ± 8.0% with T-/TAP approach. Overlaying layers of struts in the Crush and Culotte techniques lead to a significantly higher rate of strut malapposition in the proximal vessel than with the T-/TAP technique (Crush: 39.1 ± 10.7%, Culotte: 26.1 ± 7.7%, TAP: 4.2 ± 7.2%, P<0.01). Maximal wall-malapposed strut distance was also found on average to be higher with the Crush (1.36 ± 0.4mm) and Culotte techniques (1.32 ± 0.1mm) than with T-/TAP (1.08 ± 0.1mm, P=0.04)., Conclusions: In this model, the Crush technique resulted in a higher risk of malapposition than either the Culotte or T-/TAP technique.

Objectives: This study sought to evaluate post-dilation strategies in bifurcation stenting., Background: In bifurcation stenting practice, it is still controversial how post-dilation should be performed and whether the kissing balloon (KB) technique is mandatory when only the main vessel (MV) receives a stent., Methods: A series of drug-eluting stents (DES) (n = 26) were deployed in a coronary bifurcation model following a provisional approach. After the deployment of the stent in the MV, post-dilation with the KB technique was compared with a 2-step, sequential post-dilation of the side branch (SB) and MV without kissing., Results: The percentage of the SB lumen area free of stent struts was similar after KB (79.1 ± 8.7%) and after the 2-step sequence (74.4 ± 11.6%, p = 0.25), a considerable improvement compared with MV stenting only without dilation of the stent at the SB ostium (30.8 ± 7.8%, p < 0.0001). The rate of strut malapposition in the ostium was 21.3 ± 9.2% after KB and 24.9 ± 10.4% after the 2-step sequence, respectively, a significant reduction compared with a simple SB dilation (55.3 ± 16.8%, p < 0.0001) or MV stenting only (47.0 ± 8.5%, p < 0.0005). KB created a significant elliptical overexpansion of the MV lumen, inducing higher stress concentration proximal to the SB. KB also led to a higher risk of incomplete stent apposition at the proximal stent edge (30.7 ± 26.4% vs. 2.8 ± 9.6% for 2-step, p = 0.0016)., Conclusions: Sequential 2-step post-dilation of the SB and MV may offer a simpler and more efficient alternative to final KB technique for provisional stenting of bifurcations., (Copyright © 2012 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: The treatment of in-stent restenosis (ISR) remains a challenge with poor immediate results and higher restenosis rate than in de novo lesions. We propose, based on a consecutive series of patients treated with cutting balloon, a strategy of aggressive device selection based on the results of serial FD-OCT assessment., Methods and Results: Fourteen consecutive ISR lesions were evaluated both angiographically and with frequency domain optical coherence tomography (FD-OCT) (C7; LightLab Imaging Inc., Westford, MA, USA). Cutting balloon (CB) was used in all cases, sized firstly according to conventional angiographic criteria and then upgraded based on OCT assessment with the aim of creating cuts as close as possible to the struts. OCT data analysis included measurements of lumen and stent area, minimal distance lumen-struts and residual plaque neointimal hyperplasia. With an OCT guided CB strategy, the final minimal lumen cross-sectional area (MLCSA) after the final treatment reached 6.68±1.14 mm², with a reduction from 69% to 25% of neointimal hyperplasia. In the patients with a two-step strategy using a first CB guided by angiography and a second CB guided by OCT, the increase in CB diameter was 0.5 mm, achieving an increase in MLCSA area from 4.9±0.42 to 6.35±0.92 mm² with a reduction from 41% to 27% of neointimal hyperplasia., Conclusions: The OCT measurements of strut-to-strut distance allow safe upsizing of the CB with an acceptable lumen increase before deployment of a new DES. The strategy appears of particular usefulness for a DEB strategy with no intention to implant new stents.

Stent thrombosis remains an infrequent but significant complication following percutaneous coronary intervention. Preclinical models to rapidly screen and validate therapeutic compounds for efficacy are lacking. Herein, we describe a reproducible, high throughput and cost-effective method to evaluate candidate therapeutics and devices for either treatment or propensity to develop stent thrombosis in an in vitro bench-top model. Increasing degree of stent malapposition (0.00 mm, 0.10 mm, 0.25 mm and 0.50 mm) was associated with increasing thrombosis and luminal area occlusion (4.1 ± 0.5%, 6.3 ± 0.5%, 19.7 ± 4.5%, and 92.6 ± 7.4%, p < 0.0001, respectively). Differences in stent design in the form of bare-metal, drug-eluting, and bioresorbable vascular scaffolds demonstrated differences in stent thrombus burden (14.7 ± 3.8% vs. 20.5 ± 3.1% vs. 86.8 ± 5.3%, p < 0.01, respectively). Finally, thrombus burden was significantly reduced when healthy blood samples were incubated with Heparin, ASA/Ticagrelor (DAPT), and Heparin+DAPT compared to control (DMSO) at 4.1 ± 0.6%, 6.9 ± 1.7%, 4.5 ± 1.2%, and 12.1 ± 1.8%, respectively (p < 0.01). The reported model produces high throughput reproducible thrombosis results across a spectrum of antithrombotic agents, stent design, and degrees of apposition. Importantly, performance recapitulates clinical observations of antiplatelet/antithrombotic regimens as well as device and deployment characteristics. Accordingly, this model may serve as a screening tool for candidate therapies in preclinical evaluation. [ABSTRACT FROM AUTHOR]

Background--The long-term fate of Absorb bioresorbable vascular scaffold (Abbott Vascular, Santa Clara, CA) struts jailing side branch ostia has not been clarified. We therefore evaluate serially (post-procedure and at 6 months, 1, 2, 3, and 5 years) the appearance and fate of jailed Absorb bioresorbable vascular scaffold struts. Methods and Results--We performed 3-dimensional optical coherence tomographic analysis of the ABSORB Cohort B trial (A Clinical Evaluation of the Bioabsorbable Everolimus Eluting Coronary Stent System in the Treatment of Patients With De Novo Native Coronary Artery Lesions) up to 5 years using a novel, validated cut-plane analysis method. We included 29 patients with a total of 85 side branch ostia. From the 12 ostia which could be assessed in true serial fashion, 7 showed a pattern of initial decrease in the ostial area free from struts, followed by an increase in strut-free ostial area toward the end of the 5 years of follow-up. In a repeated-measures analysis with time as fixed variable and ostial area free from struts as dependent variable, we showed a numeric decrease in the estimated ostial area free from struts from 0.75 mm2 (baseline) to 0.68 mm2 (first follow-up visit at 6 months or 1 year) and 0.63 mm2 (second follow-up visit at 2 or 3 years). However, from the second visit to the 5-year follow-up visit, there was a statistically significant increase from 0.63 to 0.89 mm2 (P=0.001). Struts overlying an ostium divided the ostium into compartments, and the number of these compartments decreased over time. Conclusions--This study showed that in most cases, the side branch ostial area free from struts initially decreased. However, with full scaffold bioresorption, the ostial area free from scaffold increased between 2 to 3 years and 5 years in the vast majority of patients. [ABSTRACT FROM AUTHOR]

Advances in the understanding of healing mechanisms after stent implantation have led to the recognition of stent strut thickness as an essential factor affecting re-endothelialization and overall long term vessel healing response after Percutaneous Coronary Interventions (PCI). Emergence of Drug-eluting stents (DESs) with anti-proliferative coating has contributed to reducing the incidence of restenosis and Target Lesion Revascularization (TVR), while progress and innovations in stent materials have in the meantime facilitated the design of newer platforms with more conformability and thinner struts, producing lesser injury and improving integration into the vessel wall. Recent advances in biodegradable metal and polymer materials now also allow for the design of fully biodegradable platforms, which are aimed at scaffolding the vessel only temporarily to prevent recoil and constrictive remodeling of the vessel during the initial period required, and are then progressively resorbed thereby avoiding the drawback of leaving an unnecessary implant permanently in the vessel. The aim of this article is to review recent evolution in stent material and stent strut design while understanding their impact on PCI outcomes. The article describes the different metallic alloys and biodegradable material properties and how these have impacted the evolution of stent strut thickness and ultimately outcomes in patients. [ABSTRACT FROM AUTHOR]

Bioresorbable scaffolds have the potential to introduce a paradigm shift in interventional cardiology, a true anatomical and functional “vascular restoration” instead of an artificial stiff tube encased by persistent metallic foreign body. Early clinical studies using the first commercially available drug-eluting bioresorbable vascular scaffold (BVS) reported very promising safety and efficacy outcomes, comparable to best-in-class second-generation drug-eluting metal stent. To date, more than 60,000 Absorb BVSs have been implanted with only the interim analysis of one randomized trial (ABSORB II RCT) available. Recent registries have challenged the initial claim that BVS is immune from Scaffold Thrombosis (ST). However, suboptimal device expansion and insufficient intracoronary imaging guidance can explain higher than expected ST, especially in complex lesions. The aim of this review article is to critically evaluate the results of the available Absorb BVS studies and discuss the lessons learned to optimize lesion selection and implantation technique of such devices. [ABSTRACT FROM AUTHOR]

Abstract: Objective: To evaluate the role of Frequency domain optical coherence tomography (FD-OCT) in guiding stent implantation procedures. Methods: Dragonfly™-imaging catheter was used pre-intervention, after pre-dilatation or at various stages of stent deployment/post-dilatation to assess lesion severity, characteristics and guide stent expansion/apposition. Results: We performed 398 OCT pull-backs in 108 consecutive patients. The 371 pull-backs analysable, had an average length of 35mm and encompassed 193 lesions (1.8 lesions per patient). Seventy-six percent of patient had AHA-ACC-class B–C lesions. In the pre-intervention group deferral of treatment was decided for 13/68 pullbacks (19.1%), whereas strategies different from conventional predilatation (e.g. thrombectomy, rotablator, cutting-balloon) were decided in 23 cases (33.8%). After full lesion dilatation 96 pullbacks (25.9%, pre-stenting group) were performed, 46 (47.9%) of which suggested proceeding directly with stenting while 50 (52.1%) suggesting further treatment. Out of the 207 pullbacks in post-stenting group, 29 (14%) suggested new stent implantation because of dissection or residual stenosis; 64 (30.9%) suggested further optimization with high pressure/larger-sized balloon. Average number of pull-backs per patient was 3.4 requiring 75.8±19.3ml of iopamidol. No major complications were observed. Five cases (4.6%) of contrast-induced nephropathy were reported. Conclusions: Repeated examinations with FD-OCT can be safely used to guide stent selection and improve stent expansion and apposition. [Copyright &y& Elsevier]