Conventional Bare Metal Stents Research Articles

DRug-coated Balloon for Endovascular treatment of sYmptOmatic intracraNial stenotic Disease (DR. BEYOND): the protocol of a multicentre randomised trial

BackgroundAlthough endovascular stenting is considered an effective and safe therapeutic option for symptomatic intracranial atherosclerotic disease (sICAD), an elevated rate of restenosis remains an important issue for the conventional bare-metal...

Beneficial effects of high-density lipoprotein (HDL) on stent biocompatibility and the potential value of HDL infusion therapy following percutaneous coronary intervention.

Several epidemiological studies have shown a clear inverse relationship between serum levels of high-density lipoprotein cholesterol (HDL-C) and the risk of atherosclerotic cardiovascular disease (ASCVD), even at low-density lipoprotein cholesterol levels below 70 mg/dL. There is much evidence from basic and clinical studies that higher HDL-C levels are beneficial, whereas lower HDL-C levels are detrimental. Thus, HDL is widely recognized as an essential anti-atherogenic factor that plays a protective role against the development of ASCVD. Percutaneous coronary intervention is an increasingly common treatment choice to improve myocardial perfusion in patients with ASCVD. Although drug-eluting stents have substantially overcome the limitations of conventional bare-metal stents, there are still problems with stent biocompatibility, including delayed re-endothelialization and neoatherosclerosis, which cause stent thrombosis and in-stent restenosis. According to numerous studies, HDL not only protects against the development of atherosclerosis, but also has many anti-inflammatory and vasoprotective properties. Therefore, the use of HDL as a therapeutic target has been met with great interest. Although oral medications have not shown promise, the developed HDL infusions have been tested in clinical trials and have demonstrated viability and reproducibility in increasing the cholesterol efflux capacity and decreasing plasma markers of inflammation. The aim of the present study was to review the effect of HDL on stent biocompatibility in ASCVD patients following implantation and discuss a novel therapeutic direction of HDL infusion therapy that may be a promising candidate as an adjunctive therapy to improve stent biocompatibility following percutaneous coronary intervention.

SICI-GISE Position paper on the use of the magnesium bioresorbable scaffold Magmaris in clinical practice

Bioresorbable scaffolds have emerged as a potential breakthrough for the treatment of coronary artery lesions. The need for drug release and plaque scaffolding is temporary, and leaving a permanent stent once the process of plaque recoil and vessel healing has ended might be superfluous or even deleterious exposing the patient to the risk of very late thrombosis, eliminating vessel reactivity, impairing non-invasive imaging and precluding possible future surgical revascularization. This long-term potential limitation of permanent bare metal stents might be overcome by using a resorbable scaffold. The metallic and antithrombotic properties makes the resorbable magnesium scaffold an appealing technology for the treatment of coronary artery lesions. Notwithstanding this, its mechanical properties substantially differ from those of conventional bare metal stents, and previous experience using polymer-based scaffolds has shown that a standardized implantation technique and optimal patient and lesion selection are key factors for a successful implantation. A panel of expert cardiologists gathered to find a consensus on the best practices for Magmaris implantation in a selected patient population and to discuss the rationale for new potential future indications.

Examination of Drug-eluting Coatings of Coronary Artery Stents

Abstract Drug-eluting stents provide a solution for treating restenosis in arteries expanded by using conventional bare metal stents, but there are a small number of publications on the processes of coating damage established due to the various effects that occur during the life cycle of the stent. In the current research damage to the coating was investigated along with the effects of damage on the corrosion resistance of the stent in multiple ways. This research investigates not only traditional drug eluting stents with polymer matrix, but also the new generation of polymer-free types.

A Novel Tracheobronchial Stent Loaded with 125I Seeds in Patients with Malignant Airway Obstruction Compared to a Conventional Stent: A Prospective Randomized Controlled Study

BackgroundTo evaluate the safety and efficacy of a novel radioactive bare metal stent (RBMS) compared with a conventional bare metal stent (CBMS) in patients with inoperable malignant airway obstruction. MethodsThis prospective study was approved by the Institutional Ethics Committee, and informed consent was obtained from each participant. Patients with malignant airway obstruction who had dyspnea were randomly assigned to receive RBMS or CBMS placement. The primary endpoint was stenosis grade, while the secondary endpoints were technical success, overall survival, and complications. A p value of <0·05 was considered statistically significant. ResultsBetween September 2013 and July 2015, 66 patients with inoperable malignant airway obstruction received stent placement fluoroscopically (33 in either group). The median follow-up time was 154 days (range, 15–335 days). The baseline stenosis was immediately relieved in both groups after stent placement, and the stenosis grades in the RBMS group were significantly lower than that in the CBMS group since the second month (p < 0·05). The technical success rates of stent placement were 100% in both groups. The median survival in the RBMS group was significantly longer than that in the CBMS group (170 days vs. 123 days, p < 0·05). There was no significant difference in the incidence of complications between the two groups (p < 0·05). ConclusionsThe placement of RBMS in patients with inoperable malignant airway obstruction is feasible and safe, and it significantly reduces restenosis and improves overall survival compared with the placement of CBMS.

Effects of bifurcation-specific and conventional stents on coronary bifurcation flow. An experimental and numerical study

Our paper builds on existing research into conventional bare metal stents in order to assess new devices specifically designed for coronary bifurcation angioplasty. The first aim is to validate the numerical model against data from in vitro experiments on stented coronary phantoms. A surface mesh was built in accordance with micro-computed tomography images obtained from coronary stents implanted in silicone models and used for numerical analysis. Computational simulations for steady and unsteady cases generally agreed with their experimental counterparts. A second objective is to compare the hemodynamic performance of one of these new devices (Stentys) to that of conventional devices and stenting techniques in a simplified coronary bifurcation model. Four different coronary bifurcation stenting techniques were analyzed. We have focused on factors contributing to restenosis, such as wall shear stress (WSS), oscillatory shear index (OSI), pressure loss, and local normalized helicity (LNH). It was found that bifurcation-specific stents implanted in the side branch led to increased malapposition. This effect has proved to be more important than stent specific design characteristics such as strut size (different for conventional and Stentys stent). This conclusion is confirmed by means of drop in pressure and mechanical energy loss rate calculation; for the latter, the increase ranged from 9% to 17%, depending on the stenting technique, when dedicated stents were implanted in the side branch. The behavior patterns presented in this study should be double-checked against those obtained in more realistic geometries.

Computational Bench Testing to Evaluate the Short-Term Mechanical Performance of a Polymeric Stent.

Over the last decade, there has been a significant volume of research focussed on the utilization of biodegradable polymers such as poly-L-lactide-acid (PLLA) for applications associated with cardiovascular disease. More specifically, there has been an emphasis on upgrading current clinical shortfalls experienced with conventional bare metal stents and drug eluting stents. One such approach, the adaption of fully formed polymeric stents has led to a small number of products being commercialized. Unfortunately, these products are still in their market infancy, meaning there is a clear non-occurrence of long term data which can support their mechanical performance in vivo. Moreover, the load carry capacity and other mechanical properties essential to a fully optimized polymeric stent are difficult, timely and costly to establish. With the aim of compiling rapid and representative performance data for specific stent geometries, materials and designs, in addition to reducing experimental timeframes, Computational bench testing via finite element analysis (FEA) offers itself as a very powerful tool. On this basis, the research presented in this paper is concentrated on the finite element simulation of the mechanical performance of PLLA, which is a fully biodegradable polymer, in the stent application, using a non-linear viscous material model. Three physical stent geometries, typically used for fully polymeric stents, are selected, and a comparative study is performed in relation to their short-term mechanical performance, with the aid of experimental data. From the simulated output results, an informed understanding can be established in relation to radial strength, flexibility and longitudinal resistance, that can be compared with conventional permanent metal stent functionality, and the results show that it is indeed possible to generate a PLLA stent with comparable and sufficient mechanical performance. The paper also demonstrates the attractiveness of FEA as a tool for establishing fundamental mechanical characteristics of polymeric stent performance.

MGuard Embolic Protection Stent – The Importance of Thrombus Management in ST-elevation Myocardial Infarction Primary Percutaneous Coronary Intervention

Distal embolisation of atherothrombotic material is a frequent consequence of percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). This causes microvascular occlusions, leading to a further reduction in myocardial reperfusion. The MGuard™ embolic protection stent (EPS) features a unique polymer micronet mesh coating. When used in acute STEMI, the MGuard EPS shows significant improvement in myocardial flow and ST resolution, even in complicated clinical cases vs the standard approach with conventional bare metal or drug-eluting stents. Data from the andomised Safety and Efficacy Study of MGuard Stent After a Heart Attack (MASTER II) trial and from a real-life registry have shown the efficacy and safety of the MGuard in primary PCI. This report of the proceedings of a symposium at EuroPCR, 20-23 May 2014, Paris, France, discussed clinical trial data, as well as a number of clinical cases, illustrating the utility of the MGuard EPS in difficult situations.

Randomized comparison of Zotarolimus-Eluting Endeavor Sprint versus bare-metal stent implantation in uncertain drug-eluting stent candidates: Rationale, design, and characterization of the patient population for the Zotarolimus-eluting Endeavor Sprint stent in Uncertain DES Candidates study

The use of drug-eluting stent (DES) instead of bare-metal stent (BMS) in patients at high stent thrombosis or bleeding risk as well as in those at low restenosis risk (ie, uncertain DES candidates) remains a matter of debate. Zotarolimus-Eluting Endeavor Sprint stent (E-ZES) (Santa Rosa, CA) is a hydrophilic polymer-based second-generation device with unique drug fast-release profile, which may allow for a shorter dual antiplatelet therapy (DAPT) duration without safety concerns. The primary objective is to assess whether E-ZES implantation followed by a shorter than currently recommended course of DAPT will decrease the incidence of 12-month major adverse cardiovascular events as compared with BMS in undefined DES recipients. Actual duration of DAPT regimen will be dictated by patients' characteristics and not by stent type and, as such, can be as short as 30 days after intervention in both stent groups. The ZEUS study is an open-label randomized clinical trial conducted at 20 clinical sites in Italy, Switzerland, Portugal, and Hungary. With 1,600 individuals, this study will have 85% power to detect a 33% difference in the primary end point consisting of the composite of death, nonfatal myocardial infarction, or target vessel revascularization. The ZEUS trial aims to assess whether the use of E-ZES, followed by a DAPT duration regimen based on patients' characteristics and not by stent type, is superior to conventional BMS implantation in undefined DES recipients who qualify for the presence of high thrombosis, bleeding, or low restenosis risk criteria.

Advances in Coronary Stent Technology - Active Drug-Loaded Stent Surfaces for Prevention of Restenosis and Improvement of Biocompatibility

Beyond their originally sole mechanical function, current drug-eluting stents (DES) implement the concept of local drug delivery for the re-opening of stenotic arterial vessels, and for prevention of in-stent restenosis as one of the major limitations of conventional bare metal stents (BMS). Current DES consist of a permanent metallic stent platform and an active agent being released from a drug-incorporated polymer coating or a porous stent surface. Although DES have impressively demonstrated their capability of reducing in-stent restenosis, their safety remains under debate due to potential risks, such as delayed healing, late thrombosis and hypersensitivity demanding further development. Current advancements in the stent design address the stent platform, the pharmacologically active substance and/or the drug carrier. For instance, novel biocompatible absorbable stent platforms and drug carriers are developed and novel drugs with a differential effect on vascular endothelial and smooth muscle cells, providing efficient inhibition of muscle cells without altering the endothelial cell function, are identified. Moreover, biofunctionalization of the stent's surface with capture molecules for endothelial progenitor cells are under investigation in order to achieve an in situ endothelialization of the implant. In this context, this review paper discusses the current advances in coronary stent technology with a special focus on novel stent platforms, drugs and stent coatings for the prevention of restenosis and improvement of biocompatibility.

Transjugular intrahepatic portosystemic shunt using the FLUENCY expanded polytetrafluoroethylene-covered stent

The aim of this study was to evaluate the feasibility of transjugular intrahepatic portosystemic shunts using FLUENCY expanded polytetraf luoroethylene (PTFE)-covered stents and the effect on the patency rate. A total of 114 cirrhotic patients who were treated by transjugular intrahepatic portosystemic stent shunt (TIPS) placement using a FLUENCY expanded, PTFE-covered stent were enrolled in the present study. Of the patients, 15 underwent an additional bare metal stent implantation on the portal side of the covered stent, simultaneously. Patients underwent Doppler sonography during the follow-up. Mean portal venous pressure dropped from 2.499±0.588 cmHg to 1.764±0.294 cmHg. The cumulative patency rates for one and two years were 86.7% and 75.2%, respectively. The results demonstrate the feasibility of TIPS placement with the FLUENCY expanded PTFE-covered stent. TIPS placement with the FLUENCY expanded PTFE-covered stent was able to improve patency when compared with the use of conventional bare-metal stents.

The edge vascular response following implantation of a fully bioresorbable device: ‘A miss always counts’

The application of drug-eluting stents (DES) and more recently that of bioresorbable scaffolds has tremendously reduced the rate of in-stent/ scaffold restenosis compared to conventional bare-metal stents (BMS) in the treatment of coronary artery disease. The use of radioactive stents during the transition from BMS to DES transiently eliminated the phenomenon of in-stent restenosis; however although brachytherapy was a reasonable solution the main pitfall of this treatment approach was the edge vascular response (EVR) or “candy–wrapper” effect [1]. Since then the EVR has been investigated with first generation DES short term (6-months) [2] and bioresorbable vascular scaffolds (BVS) midterm up to 1-year [3]. We demonstrate two selected cases of proximal edge stenosis resulting in target lesion revascularization as a consequence of geographical miss (GM) following implantation of the ABSORB BVS from the ABSORB Extend (Case 1) and ABSORB Cohort B trials (Case 2).

A multicenter randomized comparison of drug‐eluting balloon plus bare‐metal stent versus bare‐metal stent versus drug‐eluting stent in bifurcation lesions treated with a single‐stenting technique: Six‐month angiographic and 12‐month clinical results of the drug‐eluting balloon in bifurcations trial

Percutaneous treatment of coronary bifurcation lesions remains hampered by suboptimal results, mainly in the side branch (SB), even with the use of drug-eluting stents (DES). Paclitaxel drug-eluting balloons (DEB) could provide an attractive alternative to treat bifurcations in combination with a provisional T-stenting technique in order to minimize SB restenosis. We compared angiographic and clinical outcomes of a provisional T-stenting technique with a DEB plus bare-metal stent (BMS) versus BMS versus paclitaxel DES. In this randomized, international, multicenter, single-blinded 3-arm study, 117 patients with coronary bifurcation lesions underwent treatment with: (A) DEB in both main branch (MB) and SB and BMS in MB; (B) BMS in MB and regular balloon angioplasty in SB; or (C) paclitaxel DES in MB and regular balloon in SB. All patients underwent provisional T-stenting with an identical stent platform in the MB. Paclitaxel was the drug for elution in groups A and C. The primary endpoint was 6-month angiographic late luminal loss. Secondary end points were 6-month binary restenosis and 12-month major adverse cardiac events (MACE: death, myocardial infarction, target vessel revascularization). The procedure was successful in all cases. Late luminal loss, measured respectively in the proximal MB, distal MB and SB was 0.58 ± 0.65, 0.41 ± 0.60, and 0.19 ± 0.66 mm in group A; 0.60 ± 0.65, 0.49 ± 0.85, and 0.21 ± 0.57 mm in group B; and 0.13 ± 0.45, 0.19 ± 0.64, and 0.11 ± 0.43 mm in group C (P = 0.001). Binary restenosis rates per bifurcation and MACE rates were 24.2%, 28.6%, and 15% (P = 0.45) and 20%, 29.7%, and 17.5% (P = 0.40) in groups A, B, and C, respectively. Pretreatment of both MB and SB with DEB failed to show angiographic and clinical superiority over conventional BMS, using a provisional T-stenting technique. Moreover DES showed superior angiographic results than DEB and BMS.

Drug-eluting stents in multivessel coronary artery disease: cost effectiveness and clinical outcomes.

Multivessel coronary artery disease is more often treated either with coronary artery bypass surgery (CABG) or percutaneous coronary intervention (PCI) with stenting. The advent of drug-eluting stent (DES) has changed the revascularization strategy, and caused an increase in the use of DES in multivessel disease (MVD), with reduced rate of repeat revascularization compared to conventional bare metal stent. The comparative studies of DES-PCI over CABG have shown comparable safety; however, the rate of major adverse cerebrovascular and cardiac events and repeat revascularization was significantly higher with DES-PCI at long term. In diabetic patients with MVD, concern of repeat revascularization with DES-PCI is persistent. More recent, one-year economic outcomes have reported that the CABG is favored among patients with high angiographic complexity. The higher rate of repeat revascularization with DES-PCI in MVD would lead to increased economic burden on patient at long term besides bearing high cost of DES. In diabetic MVD patients, CABG is associated with having better clinical outcomes and being more cost-effective approach when compared to DES-PCI at long term.

Beta Titanium Alloys with Very High Ductility Induced by Complex Deformation Mechanisms: a New Material Perspective for Coronary Stent Applications

The increased use of metallic biomaterials in contact with blood e.g. for application as coronary stents is steadily resulting in the development of new biomaterials. Conventional bare-metal stents made by stainless steel were reported on adverse reactions against human body and are gradually replaced by coated stainless steel. The new generation of stent requires fundamental improvements at the materials point of view. Although titanium and classical Ti-alloys display superior biocompatibility compared to other metallic materials (stainless steels, Co-Cr), the major drawback of their relatively low ductility (typically 15%-25% of elongation) seriously limits their applications as cardiovascular stents, where large ductility is basically required during the stent deployment procedure and long-term service. In this paper, new titanium alloys with high ductility, a binary Ti-12Mo (wt%) and a ternary Ti-9Mo-6W (wt%) were designed by using a chemical formulation strategy based on the electronic design method called “the d-electron alloy design method”. Both alloys were synthesized and thermo-mechanically treated into beta-metastable state. In tensile tests, both alloys exhibited outstanding ductility of 43% and 46% in total elongation at room temperature, which is almost two times greater than the normal value shown with classical titanium alloys. Optical microscopy and detailed TEM observations on the deformed specimens revealed a complex deformation mechanism, involving {332}&lt;113&gt; mechanical twinning, stress induced plate shaped omega phase and stress induced martensitic (SIM) transformation β-α’’.

Effect of MGuard Net Protective Stent on the Release of Troponin I in Patients With Acute Coronary Syndromes A Randomized Controlled Trial

This study was designed to determine whether the treatment of patients with unstable angina pectoris or non-Q-wave myocardial infarction with a stent containing a protection net to prevent coronary microembolization affects the severity of biomarker release.The MGuard stent (InspireMD, Tel Aviv, Israel) was designed as a plaque/thrombus-trapping device, using a conventional bare metal stent covered with an ultrathin, flexible mesh net. We hypothesized that this stent would partly eliminate distal embolization and decrease subsequent troponin I (TnI) release.Forty-six acute coronary syndrome patients referred for percutaneous coronary intervention (PCI) were included and randomized in this study. Serum concentrations of TnI were measured prior to, as well as 24 and 48 hours after, the PCI procedure.Technical success was 95% and 100% in the MGuard group and non-MGuard group, respectively. A transient no-reflow phenomenon was observed in one interventional procedure in each group of patients (5% versus 4%; NS). Two patients (one in each group) died during the hospital stay. There was no statistically significant difference in median postprocedural TnI levels in either group.The results suggest that coronary stenting with a stent system containing a protection net to prevent coronary microembolization (eg the MGuard stent) in patients with acute coronary syndromes does not decrease procedural myocardial injury, as measured by TnI release. It seems likely that stenting with the MGuard stent is feasible, however, its safety should be verified in larger studies.

Role of Bare-Metal Stents for Left Main Coronary Artery Disease in the Era of Drug-Eluting Stents - Which Coronary Stent Should Be Used for Left Main Trunk Disease? BMS or DES? (BMS-Side) -

In the past, coronary artery bypass graft surgery has been applied to revascularization for unprotected left main coronary artery (ULMCA) disease. In recent years, due to the advent of drug-eluting stents (DES), restenosis rates have decreased in comparison to conventional bare-metal stents (BMS), and the range of applications of percutaneous coronary intervention (PCI) for ULMCA disease has been expanded. However, even if DES is used, outcomes of PCI for distal left main coronary artery bifurcation lesions are not sufficient. Moreover, problems specific to DES, such as late stent thrombosis and late catch-up phenomenon, have been identified. There are still unknown points regarding remote-stage outcomes of DES. Thus, further investigation is needed on PCI for ULMCA disease, along with further analysis of remote-stage outcomes of BMS.

Development and performance of the zotarolimus-eluting Endeavor® coronary stent

Given statistically significant and clinically meaningful reductions in angiographic restenosis and repeat revascularization, treatment with drug-eluting stents (DESs) has become established as a standard of care in percutaneous coronary revascularization. However, despite their superior efficacy compared with conventional bare metal stents, experiences with first-generation DESs from both clinical trials and real-world practice have raised attention to the late safety risk of stent thrombosis that may be related to biologic incompatibility, delayed vessel healing and/or impaired endothelial function. To address the outstanding needs related to DES safety and deliverability while maintaining efficacy, the Endeavor® zotarolimus-eluting stent (Medtronic CardioVascular, CA, USA) is distinguished by favorable safety and efficacy demonstrated in clinical trials and usual practice. The purpose of this article is to describe the mechanical and pharmacologic features of the Endeavor stent, provide an overview of comparative trial results of the Endeavor stent with bare metal stents and alternative DESs, and detail recent and developing trials specific to the Endeavor stent that provide further insight to stent biocompatibility and safety.

Long-Term Clinical and Angiographic Outcome of Cobalt Alloy Stents Compared to Conventional Bare-Metal Stents and Paclitaxel-Eluting Stents

Long-Term Clinical and Angiographic Outcome of Cobalt Alloy Stents Compared to Conventional Bare-Metal Stents and Paclitaxel-Eluting Stents

Experimental study of an endothelial progenitor cell coated stent in transjugular intrahepatic portosystemic shunt

Objective To evaluate the efficacy of a self-expandable metal stent coated with autologous endothelial progenitor cells(EPCs)for prevention of restenosis in transjugular intrahepatic portosystemic shunt(TIPS)in a swiue model.Methods EPCs were coated on the metal stents using fibrin gel before TIPS procedure.TIPS was performed in 15 young adult pigs,using an autologous EPC-seeded stent(treatment group,n=9)or a conventional bare metal stent(control group,n=6).All pigs were sacrificed at 2 weeks after TIPS procedure.Portography was performed immediately before the euthanasia.Gross and microscopic pathological exams and immunohistochemical exams of the TIPS track specimens were performed.Fisher test and t test were used to analyse the data.Results TIPS was performed successfully in all the 15 swine.On day 14 of follow-up,direct portography and necropsy demonstrated that 5 shunts remained patent,2 shunts stenosed,and the remaining 2 shunts occluded in the treatment group(n=9);while 5 shunts were occluded and one shunt was stenotic in the control group(n=6).The patency rate was 56%vs 0(P=0.03)between the two groups.Histological analyses showed a greater pseudo-intimal hyperplasia in the TIPS track of the control group than that of the treatment group(pseudointimal thickness at hepatic vein,hepatic parenchyma and portal vein site was(1.2±0.4),(1.3±0.5),(1.5±0.4)mmvs(1.0±0.6),(0.9±0.5),(1.0±0.4)mm respectively(P＜0.05).Conclusion The EPC-coated metal stent is feasibly constructed in vitro and improves the patency in TIPS in a porcine model. Key words: Portasystemic shunt,transjugular intrahepatic; Stem cells; Stent