Pivotal, randomized U.S. study of the Symbiot™ covered stent system in patients with saphenous vein graft disease: Eight-month angiographic and clinical results from the Symbiot III trial

Polymeric Semiconductor in Field-Effect Transistors Utilizing Flexible and High-Surface Area Expanded Poly(tetrafluoroethylene) Membrane Gate Dielectrics

Organic field-effect transistors (OFETs) were fabricated using three high-surface area and flexible expanded-poly(tetrafluoroethylene) (ePTFE) membranes in gate dielectrics, along with the semiconducting polymer poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2':5',2″:5″,2‴-quaterthiophen-5,5‴-diyl)] (PDPP4T). The transistor behavior of these devices was investigated following annealing at 50, 100, 150, and 200 °C, all sustained for 1 h. For annealing temperatures above 50 °C, the OFETs displayed improved transistor behavior and a significant increase in output current while maintaining similar magnitudes of Vth shifts when subjected to static voltage compared to those kept at ambient temperature. We also tested the response to NO2 gas for further characterization and for possible applications. The ePTFE-PDPP4T interface of each membrane was characterized via scanning electron microscopy for all four annealing temperatures to derive a model for the hole mobility of the ePTFE-PDPP4T OFETs that accounts for the microporous structure of the ePTFE and consequently adjusts the channel width of the OFET. Using this model, a maximum hole mobility of 1.8 ± 1.0 cm2/V s was calculated for the polymer in an ePTFE-PDPP4T OFET annealed at 200 °C, whereas a PDPP4T OFET using only the native silicon wafer oxide as a gate dielectric exhibited a hole mobility of just 0.09 ± 0.03 cm2/V s at the same annealing condition. This work demonstrates that responsive semiconducting polymer films can be deposited on nominally nonwetting and extremely bendable membranes, and the charge carrier mobility can be significantly increased compared to their as-prepared state by using thermally durable polymer membranes with unique microstructures as gate dielectrics.

Saphenous Vein Graft Intervention

Even though saphenous vein grafts (SVGs) are the most commonly used surgical conduits, their long-term patency is limited by accelerated atherosclerosis often resulting in acute coronary syndrome or asymptomatic occlusion. SVG intervention is associated with 2 significant challenges: a significant risk of distal embolization with resultant periprocedural myocardial infarction in the short-term and restenosis in the long-term. Several individual trials have compared bare metal stents with drug-eluting stents for SVG intervention. This review article discusses the pathophysiology of SVG lesions, indications for SVG intervention, and the challenges encountered, and also technical considerations for SVG intervention and the supporting evidence.

ePTFE-based biomedical devices: An overview of surgical efficiency

Polytetrafluoroethylene (PTFE) is a ubiquitous material used for implants and medical devices in general because of its high biocompatibility and inertness: blood vessel, heart, table jawbone, nose, eyes, or abdominal wall can benefit from its properties in case of disease or injury. Its expanded version, ePTFE is an improved version of PTFE with better mechanical properties, which extends its medical applications. A material as frequently used as ePTFE with these exceptional properties deserves a review of its main uses, developments, and possibility of improvements. In this systematic review, we examined clinical trials related to ePTFE-based medical devices from the literature. Then, we excluded all trials using ePTFE as a control to test other devices. ePTFE-coated stents, hemodialysis and bypass grafts, guided bone and tissue regeneration membranes, hernia and heart repair and other devices are reviewed. The rates of success using these devices and their efficiency compared to other materials used for the same purposes are reported. ePTFE appears to be more or just as efficient compared to them. Some success rates remain low, suggesting the need of improvement ePTFE for medical applications.

Advances in the Post-coronary Artery Bypass Graft Management of Occlusive Coronary Artery Disease

Revascularisation of chronic total occlusion (CTO) represents one of the most challenging aspects of percutaneous coronary intervention, but advances in equipment and an understanding of CTO revascularisation techniques have resulted in considerable improvements in success rates. In patients with prior coronary artery bypass grafting (CABG) surgery, additional challenges are encountered. This article specifically explores these challenges, as well as antegrade methods of CTO crossing. Techniques, equipment that can be used and reference texts are highlighted with the aim of providing potential CTO operators adequate information to tackle additional complexities likely to be encountered in this cohort of patients. This review forms part of a wider series where additional aspects of patients with prior CABG should be factored into decisions and methods of revascularisation.

Long-term outcomes of percutaneous coronary interventions within coronary artery bypass grafts

INTRODUCTION

The long-term outcomes of percutaneous coronary interventions (PCIs) within coronary artery bypasses are still poor as compared to those within native coronary arteries. Thus, we aimed to assess predictors of long-term clinical outcomes after PCIs of coronary bypasses.

MATERIAL AND METHODS

We enrolled 194 patients after PCIs of coronary artery bypasses at the mean age of 69.5 ±8.3 years (73.2% male). The primary study endpoint was a combination of target-vessel revascularization (TVR), target-lesion revascularization (TLR), myocardial infarction (MI), stroke, coronary artery bypass grafting (CABG) and death. The mean follow-up was 964 ±799.1 days and was completed among 156 patients. Multivariate analysis was used to assess determinants of study endpoints during follow-up. Moreover, we compared survival curves according to the type of PCI and presence of anti-embolic protection.

RESULTS

The primary endpoint of the study occurred in 59.7% of patients after the mean time of 669.6 ±598.7 days. The TVR occurred in 37.9% of individuals, TLR in 24.2%, MI in 26.3%, stroke in 4.2%, CABG in 2.1% and death in 30.5% of patients. In Cox multivariate analysis, PCI of two or more bypasses (p < 0.01), post-dilatation (p < 0.05) and no-reflow (p < 0.05) were the independent determinants of the primary study endpoint. No significant impact of anti-embolic protection devices on long-term outcomes was observed.

CONCLUSIONS

Percutaneous coronary interventions of two or more bypasses, post-dilatation and no-reflow are predictors of worse outcome in patients undergoing PCI within coronary artery bypass grafts.

Comparison between the STENTYS self-apposing bare metal and paclitaxel-eluting coronary stents for the treatment of saphenous vein grafts (ADEPT trial)

AIMS

To describe the safety and performance of STENTYS self-expandable bare metal stents (BMS) versus paclitaxel-eluting stents (PES) in saphenous vein grafts (SVGs).

METHODS AND RESULTS

A randomised controlled trial was performed in four hospitals in three European countries between December 2011 and December 2013. Patients with de novo lesions (>50% stenosis) in an SVG with a diameter between 2.5-6 mm were included. Primary endpoint was late lumen loss at 6 months. Secondary endpoints included procedural success and the occurrence of major adverse cardiac events (MACE) at 12 months. A total of 57 patients were randomised to STENTYS self-apposing BMS (n = 27) or PES (n = 30). Procedural success was obtained in 89.5%. No significant differences in late lumen loss were found between BMS and PES at 6 months (0.53 mm vs 0.47; p = 0.86). MACE rates at 12 months were comparable in both groups (BMS 22.2% vs. PES 26.7%; p = 0.70).

CONCLUSIONS

Treatment of SVGs with STENTYS self-expandable stents is safe and effective. No significant differences were found in late lumen loss and MACE between BMS and PES.

Current State of the Art in Approaches to Saphenous Vein Graft Interventions

Saphenous vein grafts (SVGs), used during coronary artery bypass graft surgery for severe coronary artery disease, are prone to degeneration and occlusion, leading to poor long-term patency compared with arterial grafts. Interventions used to treat SVG disease are susceptible to high rates of periprocedural MI and no-reflow. To minimise complications seen with these interventions, proper stents, embolic protection devices (EPDs) and pharmacological selection are crucial. Regarding stent selection, evidence has demonstrated superiority of drug-eluting stents over bare-metal stents in SVG intervention. The ACCF/AHA/SCA American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Society for Cardiovascular Angiography and Interventions guidelines recommend the use of EPDs during SVG intervention to decrease the risk of periprocedural MI, distal embolisation and no-reflow. The optimal pharmacological treatment for slow or no-reflow remains unclear, but various vasodilators show promise.

Coronary covered stents

Covered stents offer an effective bail-out strategy in vessel perforations, are an alternative to surgery for the exclusion of coronary aneurysms, and have a potential role in the treatment of friable embolisation-prone plaques. The aim of this manuscript is to offer an overview of currently available platforms and to report results obtained in prior studies.

Saphenous Vein Graft Interventions

Saphenous vein graft interventions compose a small but important subset of percutaneous coronary revascularization. Because of their unique biology, percutaneous angioplasty and stenting require tailored patient and lesion selection and modification of intervention technique to optimize outcomes. The use of embolic protection and appropriate adjunctive pharmacology can help minimize periprocedural complications, such as the no-reflow phenomenon. Recommendations for best practice in saphenous vein graft interventions continue to evolve with emerging research and therapy.

Back to nature: A more natural alternative to the PTFE covered stent: Twenty-two years in the making

The introduction of easily deployed covered stents has made PCI safer. The homemade venous and PTFE covered stent were effective but not practical for sealing perforations. The novel pericardial covered stent graft goes back to a more natural covering and is more easily deployed.

Microvascular coronary flow comparison in acute myocardial infarction angioplasty treated with a mesh covered stent (MGUARD stent) versus bare metal stent: MICAMI-MGUARD

BACKGROUND

Distal embolization of thrombus/platelet aggregates decreases myocardial reperfusion during primary percutaneous coronary intervention (PCI), and is associated with worse immediate and long-term prognosis of patients with ST-elevation myocardial infarction (STEMI).

OBJECTIVE

Assess the efficacy of a mesh covered stent (MGuard™ stent, MGS) in preventing distal embolization and microvascular reperfusion impairment during primary PCI, compared with a bare metal stent (BMS).

METHODS

Forty patients with STEMI referred for primary PCI were randomized for stenting the culprit lesion with the MGS (n = 20) or a BMS (n = 20). Blinded experts performed off-line measurements of angiographic epicardial and microvascular reperfusion criteria: TIMI flow grade, myocardial blush, corrected TIMI frame count (cTFC).

RESULTS

At baseline clinical, angiographic and procedural variables were not different between groups. Post PCI TIMI flow grade was similar in both groups. We observed better myocardial Blush grade in group MGS compared to BMS (median value 3.0 vs 2.5, 2p = 0.006) and cTFC (mean cTFC: MGS 19.65 ± 4.07 vs BMS 27.35 ± 7.15, 2p < 0.001, cTFC mean difference MGS-BMS: 7.7, CI 95%: 3.94 to 11.46). MGS stent group had a higher percentage of successful angioplasty (cTFC ≤ 23: MGS 85% vs BMS 30%, 2p < 0.001). We had two cases of acute stent thrombosis (one for each group) at 30days follow up, but no clinical events at 6 months follow up.

CONCLUSIONS

In this exploratory study, MGS significantly improved microvascular reperfusion criteria compared with a BMS in primary PCI. However its safety and impact on clinical outcomes should be verified in larger randomized clinical trials.

Current percutaneous treatment strategies for saphenous vein graft disease

Coronary artery bypass graft surgery remains one of the most widely performed surgical procedures in North America and aortocoronary saphenous vein grafts (SVG) are the most frequently used surgical conduits. SVG disease (SVGD) remains the leading cause of symptomatic coronary artery disease postcoronary artery bypass graft. When optimal medical therapy is ineffective, repeat surgery is associated with higher mortality combined with less favorable clinical and angiographic results, thus percutaneous revascularization on SVG is currently the standard of care for the revascularization of SVGD. Balloon angioplasty, bare metal stents, polytetrafluoroethylene-covered stents, and drug-eluting stents have been extensively investigated for SVG interventions. Multiple recent randomized trials and meta-analyses have confirmed the pathophysiologic and clinical differences between SVGD and coronary artery disease. Decisions such as patient selection, premedication, stent, and protection device characteristics should be carefully considered to achieve optimal procedural and clinical results. Acute coronary syndromes due to SVG involvement, chronic total occlusions, retrograde approaches, and SVG perforation management are newer fields requesting additional research.

Drug-Eluting Stents Versus Bare Metal Stents in Saphenous Vein Graft Intervention

Percutaneous coronary intervention (PCI) of saphenous vein graft (SVG) is associated with higher adverse event rates, lower procedural success, and inferior longterm patency rates compared with native vessel PCI. The ability to comply with dual antiplatelet therapy, and whether the patient will need an interruption in dual antiplatelet therapy, should be considered when deciding whether to implant a drug-eluting stent (DES) or bare metal stent (BMS) in an SVG. DES should be used for SVG PCI because they seem to reduce target vessel revascularization. This article reviews the evolution and contemporary evidence regarding use of DES versus BMS in SVG PCI.

Degenerated Saphenous Vein Graft Intervention: Should We Target the Native Vessel instead?

Coronary interventions of degenerated saphenous vein grafts (SVGs) continue to present a management challenge. Although repeat coronary artery bypass grafting (CABG) remains a significant risk factor for operative mortality, percutaneous coronary intervention (PCI) is still associated with a high risk for periprocedural events. There is a lack of consensus on the optimal treatment strategy for patients with severe stenosis of SVGs. It is imperative to review the characteristics of native versus SVG disease, risk factors for complications after SVG intervention, procedural treatment strategies important to the decision on which therapeutic strategy to follow, and measures to mitigate the risks of periprocedural complications.

Management of Complications During Saphenous Vein Graft Interventions

Because of greater patient comorbidities, more diffusely diseased vessels, and the greater possibility of mechanical complications, saphenous vein graft interventions are fraught with complications. The greatest risk is a higher risk of periprocedural myocardial infarction due to distal embolization of microemboli. The risk for noreflow in a patient with concomitant native critical vessel disease can have grave consequences. Minimizing the risk of periprocedural myocardial infarction with the use of distal embolic protection, understanding the role of adjunctive pharmacotherapy, and learning how to manage less common but serious mechanical complications during saphenous vein graft interventions are important to ensure optimal patient outcomes.

Secondary revascularization after CABG surgery

CABG surgery is an effective way to improve symptoms and prognosis in patients with advanced coronary atherosclerotic disease. Despite multiple improvements in surgical technique and patient treatment, graft failure after CABG surgery occurs in a time-dependent fashion, particularly in the second decade after the intervention, in a substantial number of patients because of atherosclerotic progression and saphenous-vein graft (SVG) disease. Until 2010, repeat revascularization by either percutaneous coronary intervention (PCI) or surgical techniques was performed in these high-risk patients in the absence of specific recommendations in clinical practice guidelines, and within a culture of inadequate communication between cardiac surgeons and interventional cardiologists. Indeed, some of the specific technologies developed to reduce procedural risk, such as embolic protection devices for SVG interventions, are largely underused. Additionally, the implementation of secondary prevention, which reduces the need for reintervention in these patients, is still suboptimal. In this Review, graft failure after CABG surgery is examined as a clinical problem from the perspective of holistic patient management. Issues such as the substrate and epidemiology of graft failure, the choice of revascularization modality, the specific problems inherent in repeat CABG surgery and PCI, and the importance of secondary prevention are discussed.

Use of Microvena Snare Catheter in Non-ST Elevation Myocardial Infarction Due to Saphenous Vein Graft Occlusive Thrombi

Percutaneous coronary intervention of grafts vessel is more challenging due to a higher incidence of periprocedural distal micro-emobilization and myocardial infarction. Percutaneous coronary intervention current guidelines advocate usage of distal embolic protection devices, especially in patients with a large thrombus burden, undergoing percutaneous intervention for vein graft disease. We present a 75-year-old man with acute coronary syndrome who had saphenous vein graft thrombus. This patient was treated successfully by manual aspiration of graft thrombus using a microvena catheter. There is yet no best available therapeutic options for patients undergoing percutaneous coronary intervention of saphenous vein graft lesions.

Saphenous vein graft intervention

Saphenous vein grafts are commonly used conduits for surgical revascularization of coronary arteries but are associated with poor long-term patency rates. Percutaneous revascularization of saphenous vein grafts is associated with worse clinical outcomes including higher rates of in-stent restenosis, target vessel revascularization, myocardial infarction, and death compared with percutaneous coronary intervention of native coronary arteries. Use of embolic protection devices is a Class I indication according to the American College of Cardiology/American Heart Association guidelines to decrease the risk of distal embolization, no-reflow, and periprocedural myocardial infarction. Nonetheless, these devices are underused in clinical practice. Various pharmacological agents are available that may also reduce the risk of or mitigate the consequences of no-reflow. Covered stents do not decrease the rates of periprocedural myocardial infarction and restenosis. Most available evidence supports treatment with drug-eluting stents in this high-risk lesion subset to reduce angiographic and clinical restenosis, although large, randomized trials comparing drug-eluting stents and bare-metal stents are needed.

The State of the Art in Pulmonary Vein Stenosis -Diagnosis & Treatment

Pulmonary vein stenosis is a rare but serious complication of pulmonary vein isolation to treat atrial fibrillation. Pulmonary vein angioplasty/stenting has emerged as the treatment of choice for significantly stenotic veins. Guidelines for post ablation evaluation of the pulmonary veins, including the timing and method of surveillance for possible stenosis, the criteria for intervention, the technical aspects of intervention, and finally the surveillance post intervention, are still being developed. The relatively high rate of restenosis after intervention in a subset of patients remains a great challenge. A better understanding of the pathophysiology underlying this syndrome is needed to appropriately answer many of the remaining questions. The goal of this manuscript is to describe what has been learned about this complication and its treatment from a relatively large experience in a single institution over the past decade, and provide a comprehensive review of the existing literature in order to shed as much light on the subject as is possible, while at the same time exposing the areas that need further study.

Short- and long-term outcomes after stent-assisted percutaneous treatment of saphenous vein grafts in the drug-eluting stent era

Percutaneous treatment of saphenous vein graft (SVG) lesions has been associated with higher rates of periprocedural complications and restenosis compared with non-SVG lesions. Whether these outcomes are similar in contemporary clinical practice, particularly when drug-eluting stents are used, is unknown. We evaluated outcomes of 110 consecutive patients who were treated with stent-assisted percutaneous coronary intervention for 145 SVG lesions (drug-eluting stents used in 91.0% of lesions). Embolic protection devices were used in 52.1% of treated grafts. Adverse events were recorded up to 1 year. Major or minor periprocedural myocardial necrosis occurred in 11 patients (10.9%). At 1-year clinical follow-up, we observed 13 myocardial infarctions (13.7%), 8 target lesion revascularizations (8.4%), 18 target vessel revascularizations (19.0%), 2 stent thromboses (2.1%), and 7 deaths (7.4%). The incidence of major adverse cardiac events, defined as death, myocardial infarction, or target vessel revascularization, was 30.5% at 1 year. By multivariable analysis, the presence of thrombus inside the graft before the procedure and the length of the stented segment were independent predictors of major adverse cardiac events at 1 year (hazard ratio for thrombus 4.07, 95% confidence interval 1.90 to 8.68, p = 0.0003; hazard ratio per millimeter of stented length 1.02, 95% confidence interval 1.01 to 1.03, p = 0.025). In conclusion, our data show that patients with SVG lesions remain a high-risk subgroup with worse outcomes after percutaneous coronary intervention compared with native vessel disease even in the era of drug-eluting stents.

Randomized Double-Blind Comparison of Sirolimus-Eluting Stent Versus Bare-Metal Stent Implantation in Diseased Saphenous Vein Grafts

OBJECTIVES

We sought to compare, in a randomized fashion, sirolimus-eluting stents (SES) versus bare-metal stents (BMS) in saphenous vein grafts (SVGs).

BACKGROUND

Sirolimus-eluting stents reduce restenosis and repeated revascularization in native coronary arteries compared with BMS. However, randomized data in SVG are absent.

METHODS

Patients with SVG lesions were randomized to SES or BMS. All were scheduled to undergo 6-month coronary angiography. The primary end point was 6-month angiographic in-stent late lumen loss. Secondary end points included binary angiographic restenosis, neointimal volume by intravascular ultrasound and major adverse clinical events (death, myocardial infarction, target lesion, and vessel revascularization).

RESULTS

A total of 75 patients with 96 lesions localized in 80 diseased SVGs were included: 38 patients received 60 SES for 47 lesions, whereas 37 patients received 54 BMS for 49 lesions. In-stent late loss was significantly reduced in SES (0.38 +/- 0.51 mm vs. 0.79 +/- 0.66 mm in BMS, p = 0.001). Binary in-stent and in-segment restenosis were reduced, 11.3% versus 30.6% (relative risk [RR] 0.37; 95% confidence interval [CI] 0.15 to 0.97, p = 0.024) and 13.6% versus 32.6% (RR 0.42; 95% CI 0.18 to 0.97, p = 0.031), respectively. Median neointimal volume was 1 mm(3) (interquartile range 0 to 13) in SES versus 24 (interquartile range 8 to 34) in BMS (p < 0.001). Target lesion and vessel revascularization rates were significantly reduced, 5.3% versus 21.6% (RR 0.24; 95% CI 0.05 to 1.0, p = 0.047) and 5.3% versus 27% (RR 0.19; 95% CI 0.05 to 0.83, p = 0.012), respectively. Death and myocardial infarction rates were not different.

CONCLUSIONS

Sirolimus-eluting stents significantly reduce late loss in SVG as opposed to BMS. This is associated with a reduction in restenosis rate and repeated target lesion and vessel revascularization procedures. (The RRISC Study; http://clinicaltrials.gov/ct/show; NCT00263263).