Clinical experience with the Palmaz-Schatz coronary stent. Initial results of a multicenter study

Treatment and Care of Patients with ST-Segment Elevation Myocardial Infarction-What Challenges Remain after Three Decades of Primary Percutaneous Coronary Intervention?

Primary percutaneous coronary intervention (pPCI) has revolutionized the prognosis of ST-segment elevation myocardial infarction (STEMI) and is the gold standard treatment. As a result of its success, the number of pPCI centres has expanded worldwide. Despite decades of advancements, clinical outcomes in STEMI patients have plateaued. Out-of-hospital cardiac arrest and cardiogenic shock remain a major cause of high in-hospital mortality, whilst the growing burden of heart failure in long-term STEMI survivors presents a growing problem. Many elements aiming to optimize STEMI treatment are still subject to debate or lack sufficient evidence. This review provides an overview of the most contentious current issues in pPCI in STEMI patients, with an emphasis on unresolved questions and persistent challenges.

Preliminary Investigation on Efficacy and Safety of Substance P-Coated Stent for Promoting Re-Endothelialization: A Porcine Coronary Artery Restenosis Model

BACKGROUND

Current polymer-based drug-eluting stents (DESs) have fundamental issues about inflammation and delayed re-endothelializaton of the vessel wall. Substance-P (SP), which plays an important role in inflammation and endothelial cells, has not yet been applied to coronary stents. Therefore, this study compares poly lactic-co-glycolic acid (PLGA)-based everolimus-eluting stents (PLGA-EESs) versus 2-methacryloyloxyethyl phosphorylcholine (MPC)-based SP-eluting stents (MPC-SPs) in in-vitro and in-vivo models.

METHODS

The morphology of the stent surface and peptide/drug release kinetics from stents were evaluated. The in-vitro proliferative effect of SP released from MPC-SP is evaluated using human umbilical vein endothelial cell. Finally, the safety and efficacy of the stent are evaluated after inserting it into a pig's coronary artery.

RESULTS

Similar to PLGA-EES, MPC-SP had a uniform surface morphology with very thin coating layer thickness (2.074 μm). MPC-SP showed sustained drug release of SP for over 2 weeks. Endothelial cell proliferation was significantly increased in groups treated with SP (n = 3) compared with the control (n = 3) and those with everolimus (n = 3) (SP: 118.9 ± 7.61% vs. everolimus: 64.3 ± 12.37% vs. the control: 100 ± 6.64%, p < 0.05). In the animal study, the percent stenosis was higher in MPC-SP group (n = 7) compared to PLGA-EES group (n = 7) (MPC-SP: 28.6 ± 10.7% vs. PLGA-EES: 16.7 ± 6.3%, p < 0.05). MPC-SP group showed, however, lower inflammation (MPC-SP: 0.3 ± 0.26 vs. PLGA-EES: 1.2 ± 0.48, p < 0.05) and fibrin deposition (MPC-SP: 1.0 ± 0.73 vs. PLGA-EES: 1.5 ± 0.59, p < 0.05) around the stent strut. MPC-SP showed more increased expression of cluster of differentiation 31, suggesting enhanced re-endothelialization.

CONCLUSION

Compared to PLGA-EES, MPC-SP demonstrated more decreased inflammation of the vascular wall and enhanced re-endothelialization and stent coverage. Hence, MPC-SP has the potential therapeutic benefits for the treatment of coronary artery disease by solving limitations of currently available DESs.

Recent Advances in Stent Technology: Do They Reduce Cardiovascular Events?

PURPOSE OF REVIEW

Drug-eluting stents are used in nearly all cases of percutaneous coronary revascularization and have been shown to be superior to balloon angioplasty or bare metal stents. The designs of these stents are continually evolving to maximize efficacy and safety.

RECENT FINDINGS

This review outlines the important components of a drug-eluting stent and highlights the changes in stent design that have led to the optimization of clinical outcomes. Most stents used in contemporary times are thin strut, durable polymer drug-eluting stents (DES) that elute either everolimus or zotarolimus. Newer DES designs incorporating bioresorbable polymers or ultrathin struts have shown encouraging safety and efficacy profiles. DES are essential for the management of patients with obstructive coronary artery disease and are used in most coronary interventions. Changes in stent designs over the past 30 years reflect the ongoing need to address the limitations of earlier stents aimed to improve patient outcomes.

Evolution of drug-eluting coronary stents: a back-and-forth journey from the bench-to-bedside

Coronary stents have revolutionized the treatment of coronary artery disease. Compared with balloon angioplasty, bare-metal stents effectively prevented abrupt vessel closure but were limited by in-stent restenosis due to smooth muscle cell proliferation and neointimal hyperplasia. The first-generation drug-eluting stent (DES), with its antiproliferative drug coating, offered substantial advantages over bare-metal stents as it mitigated the risk of in-stent restenosis. Nonetheless, they had several design limitations that increased the risk of late stent thrombosis. Significant advances in stent design, including thinner struts, enhanced polymers' formulation, and more potent antiproliferative agents, have led to the introduction of new-generation DES with a superior safety profile. Cardiologists have over 20 different DES types to choose from, each with its unique features and characteristics. This review highlights the evolution of stent design and summarizes the clinical data on the different stent types. We conclude by discussing the clinical implications of stent design in high-risk subsets of patients.

Current status and outlook of biodegradable metals in neuroscience and their potential applications as cerebral vascular stent materials

Over the past two decades, biodegradable metals (BMs) have emerged as promising materials to fabricate temporary biomedical devices, with the purpose of avoiding potential side effects of permanent implants. In this review, we first surveyed the current status of BMs in neuroscience, and briefly summarized the representative stents for treating vascular stenosis. Then, inspired by the convincing clinical evidence on the in vivo safety of Mg alloys as cardiovascular stents, we analyzed the possibility of producing biodegradable cerebrovascular Mg alloy stents for treating ischemic stroke. For these novel applications, some key factors should also be considered in designing BM brain stents, including the anatomic features of the cerebral vasculature, hemodynamic influences, neuro-cytocompatibility and selection of alloying elements. This work may provide insights into the future design and fabrication of BM neurological devices, especially for brain stents.

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The current status of the application of biodegradable metals (BM) in neuroscience was presented.

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We analyzed the possibility of producing biodegradable cerebrovascular Mg alloy stents for ischemic stroke treatment.

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Key factors in designing BM brain stents were discussed.

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This work may provide insights into the future design and fabrication of BM neurological devices, especially for brain stents.

3D printing advances in the development of stents

3D printing technologies have found several applications within the biomedical sector including in the fabrication of medical devices, advanced visualization, diagnosis planning and simulation of surgical procedures. One of the areas in which of 3D printing is anticipated to revolutionised is the manufacturing of implantable bioresorbable drug-eluting scaffolds (stents). The ability to customize and create personalised tailor-made bioresorbable scaffolds has the potential to help solve many of the challenges associated with stenting, such as inappropriate stent sizing and design, abolish late stent thrombosis and help artery growth; 3D printing offers a rapid prototyping and effective method of producing stents making customization of designs feasible. This review provides an overview of the subjects and summarizes the latest research in the 3D printing technologies employed for the design and fabrication of bioresorbable stents including materials with the required printable and mechanical properties. Finally, we present a regulatory perspective on the development and engineering of 3D printed implantable stents.

Evolution of antithrombotic therapy in patients undergoing percutaneous coronary intervention: a 40-year journey

Since its introduction in 1977, percutaneous coronary intervention has become one of the most commonly performed therapeutic procedures worldwide. Such widespread diffusion, however, would have not been possible without a concomitant evolution of the pharmacotherapies associated with this intervention. Antithrombotic agents are fundamental throughout the management of patients undergoing coronary stent implantation, starting from the procedure itself to the long-term prevention of cardiovascular events. The last 40 years of interventional cardiology have seen remarkable improvements in both drug therapies and device technologies, which largely reflected a progressive understanding of the pathophysiological mechanisms of coronary artery disease, as well as procedure- and device-related adverse events. The purpose of this article is to provide an overview of the important milestones in antithrombotic pharmacology that have shaped clinical practice of today while also providing insights into knowledge gaps and future directions.

Management of ST Elevation Myocardial Infarction (STEMI) in Different Settings

ST-segment elevation myocardial infarction (STEMI) is a life-threatening condition that requires emergent, complex, well-coordinated treatment. Although the primary goal of treatment is simple to describe-reperfusion as quickly as possible-the management process is complicated and is affected by multiple factors including location, patient, and practitioner characteristics. Hence, this narrative review will discuss the recommended management and treatment strategies of STEMI in the circumstances.

First-in-Man trial of a drug-free bioresorbable stent designed to minimize the duration of coronary artery scaffolding

For the last two decades, various degradable stents have been proposed to treat coronary artery diseases and replace metallic stents to avoid residual foreign material after healing. To date, the right balance between suitable scaffolding and loss of radial strength soon after endothelium restoration is still an unmet need. The present article reports on the First-in-Man trial of a drug-free bioresorbable stent based on a lactic acid stereocopolymer composed of 98% l-lactyl units selected to release stress shielding earlier than in the case of homopoly(l-lactic acid). Thirty patients with single de novo coronary lesions were included in the trial. The fate of scaffolds was monitored by clinical and imaging follow-ups to assess rate of adverse events, acute recoil, late luminal loss, and late lumen recovery. There was no death, no myocardial infarction, and no stent thrombosis observed over the 36 months trial. Dismantling occurred about 3 months after implantation. Bioresorption was almost completed at 2 years. The late lumen loss observed at the end of the first year was partly compensated one year later by enlarging remodeling. At one year, a neointimal hyperplasia slightly greater than for drug-eluting metallic and bioresorbable stents was shown using optical coherence tomography. The excess of hyperplasia was discussed relative to struts thickness, absence of anti-proliferative drug, and release of degradation by-products.

Temporal trends in coronary intervention strategies and the impact on one-year clinical events: data from a Japanese multi-center real-world cohort study

Percutaneous coronary intervention (PCI) has significantly advanced over the last 40 years, but it is not clear whether there have been any changes in prognosis in recent years. The Kumamoto Intervention Conference Study Real-World Registry is a multi-center registry that enrolls consecutive patients undergoing PCI in 17 centers in Kyushu, Japan. To elucidate the clinical impact of recent changes in treatment strategies, 8841 consecutive participants (historical PCI: n = 4038, enrolled between January 2013 and December 2014, and current PCI: n = 4803, between January 2015 and March 2017) with 1-year follow-up data were analyzed. The incidences of major adverse cardiovascular and other clinical events were comparable between historical PCI and current PCI, even though complex lesions were more frequent during the more recent period. During this period, the use of radial approaches, drug eluting stents, and coronary imaging was greater. The use of prasugrel was more frequent (P < 0.001) during the time periods. Comparable event rates were associated with the use of clopidogrel (52.7%) and prasugrel (47.3%). In the sub-analysis for acute coronary syndrome (n = 5047), similar clinical event rates were recorded for historical and current PCI. Although the lesions to be treated are becoming more severe and complex, equivalent clinical outcomes have been maintained in recent years, possibly due to advances in the devices and medication used.

Recent Update on Peripheral Arterial Endovascular Therapy for Peripheral Arterial Occlusive Disease

Endovascular treatment is effective for symptomatic peripheral arterial disease (PAD). Following recent device improvements, favorable long-term outcomes have been achieved in iliac arteries as well as small arteries such as the femoral and popliteal arteries.

This paper outlines the history and recent advances in endovascular treatment of peripheral vascular diseases as well as the characteristics and usage of devices. The history and the advances in endovascular treatment of peripheral vascular disease have been parallel, with the development of devices such as catheters and stents. Accordingly, endovascular treatment is now recommended in guidelines as the first-line for PAD.

A Practical Approach to the Management of Complications During Percutaneous Coronary Intervention

Percutaneous coronary intervention relieves symptoms in patients with chronic ischemic heart disease resistant to optimal medical therapy and alters the natural history of acute coronary syndromes. However, adverse procedural outcomes may occur during the intervention. Knowledge of possible complications and their timely management are essential for the practicing cardiologist and can be life-saving for the patient. In this review, the authors summarize potential complications of percutaneous coronary intervention focusing on their practical management.

The OPTIMIZE randomized trial to assess safety and efficacy of the Svelte IDS and RX Sirolimus-eluting coronary stent Systems for the Treatment of atherosclerotic lesions: Trial design and rationale

Coronary stenting without angioplasty pretreatment (direct stenting) may simplify procedures in appropriate lesions. Direct stenting is facilitated by smaller profile coronary stent platforms. The present study was designed for regulatory approval of a novel drug-eluting coronary stent and incorporates both randomized comparison for non-inferiority to an approved predicate device as well as a nested evaluation of subjects eligible for direct stenting. STUDY DESIGN AND OBJECTIVES: Prospective, single-blind, randomized, active-control, multi-center study designed to assess the safety and efficacy of the novel Svelte sirolimus-eluting stent (SES) systems. A total of 1630 subjects with up to 3 target lesions will be randomized 1:1 to the Svelte SES versus either the Xience or Promus everolimus-eluting stents (control). Randomization will be stratified by whether or not a direct stenting strategy is planned by the investigator. The primary endpoint is target lesion failure (TLF) at 12 months post index procedure, defined as cardiac death, target vessel myocardial infarction, or clinically driven target lesion revascularization, and the primary analysis is a non-inferiority test with a non-inferiority margin of 3.58%. Secondary clinical endpoints include individual components of TLF, stent thrombosis and measures of procedural resource utilization including contrast administration, fluoroscopy exposure and procedural resource utilization as well as costs. CONCLUSION: The OPTMIZE Trial will evaluate the safety, efficacy and clinical value of the novel Svelte SES in subjects with up to 3 lesions, and will provide a comparison of direct stenting between randomized devices.

Vascular Intervention: From Angioplasty to Bioresorbable Vascular Scaffold

Coronary artery disease (CAD) is the leading cause of mortality and morbidity worldwide. Clinically, CAD can be potentially managed through surgical artery bypass. However, due to the highly invasive nature, surgical intervention has been gradually replaced by percutaneous transluminal coronary angioplasty and recently by percutaneous coronary revascularization using metallic stents. However, the permanent presence of metallic scaffolds inevitably impairs arterial physiology and may induce a variety of adverse effects, such as inflammation, restenosis, thrombosis, and neoatherosclerosis. To address these limitations, revascularization using bioresorbable vascular scaffolds (BVSs) has emerged as the most promising approach. After angioplasty, BVSs provide temporarily mechanical support and are completely resorbed over defined time. This transient nature allows favorable arterial remodeling and avoids thrombosis and in-stent restenosis. However, the theoretical advantages of BVSs have yet to be demonstrated. In this chapter, we first review the evolution of nonsurgical vascular intervention approaches over the past few decades. Next, we discuss the current status of BVS development and propose potential approaches to addressing the limitations associated with the current BVSs.

The History of Primary Angioplasty and Stenting for Acute Myocardial Infarction

The evolution of the management of acute myocardial infarction (MI) has been one of the crowning achievements of modern medicine. At the turn of the twentieth century, MI was an often-fatal condition. Prolonged bed rest served as the principal treatment modality. Over the past century, insights into the pathophysiology of MI revolutionized approaches to management, with the sequential use of surgical coronary artery revascularization, thrombolytic therapy, and percutaneous coronary intervention (PCI) with primary coronary angioplasty, and placement of intracoronary stents. The benefits of prompt revascularization inspired systems of care to provide rapid access to PCI. This review provides a historical context for our current approach to primary PCI for acute MI.

The Absorb bioresorbable vascular scaffold for the treatment of coronary artery disease

INTRODUCTION

Every decade the field of interventional cardiology is revolutionized by new technology. The fully bioresorbable everolimus-eluting scaffold (ABSORB BVS) technology would preserve the benefits of metallic stents by sealing balloon-induced dissections, avoiding elastic recoil and vessel occlusion. The polymeric scaffold would be resorbed to restore the natural integrity of the vessel, superseding the consequence of the permanent presence of a foreign body in the coronary artery.

AREAS COVERED

This technology evaluation focuses on the clinical evidence for the use of bioresorbable everolimus-eluting scaffold for the treatment of coronary artery disease.

EXPERT OPINION

The current generation of the bioresorbable scaffold has structural and mechanical limitations that might preclude the widespread use in clinical practice. The strut thickness (150 µm) limits deliverability and creates laminar flow disruptions that might be the nidus of an increased rate of scaffold thrombosis. In the next generation of bioresorbable scaffolds, the resorption process should be faster and in particular, strut thickness must be reduced. This will probably represent a significant step forward in an attempt to increase the efficacy and safety profile of the device and achieve a similar performance with the current generation drug-eluting stent even in complex scenarios.

The History of Coronary Stenting

The history of coronary angioplasty began with the groundbreaking work of Andreas Grüntzig, who was the first to use balloon-expandable catheters for the treatment of flow-limiting atherosclerotic coronary artery lesions. Thereafter, early investigators tested self-expanding springs as a solution to abrupt closure and restenosis seen with balloon angioplasty but these devices suffered from difficult delivery and a high complication rate. Julio Palmaz and Richard Schatz introduced the first balloon-expandable stent as a mechanical support to improve vessel patency. Their pioneering work launched a new era in the treatment of coronary artery disease.

Impact of candesartan on cardiovascular events after drug-eluting stent implantation in patients with coronary artery disease: The 4C trial

OBJECTIVE

The purpose of this study was to examine the cardiovascular protective effects of candesartan in patients undergoing percutaneous coronary intervention (PCI) with drug-eluting stents (DESs).

BACKGROUND

Candesartan has been reported to reduce cardiovascular events when therapy was started 6 months after PCI with bare-metal stents in patients who survived restenosis. Candesartan started immediately after PCI with DESs was also effective in preventing cardiovascular events.

METHODS

The 4C trial was a multicenter, prospective, randomized, open-label study. A total of 1145 patients at 39 centers in Japan were randomly assigned to receive candesartan plus standard medical treatment or standard medical treatment alone. The primary endpoints were all-cause death, and a composite of non-fatal myocardial infarction (MI), unstable angina pectoris (uAP), congestive heart failure (CHF), and non-fatal cerebrovascular events. The follow-up period was up to 3 years after the index PCI (ClinicalTrials.gov NCT00139386).

RESULTS

The incidence of total death, one of the primary endpoints, was comparable between the two treatment groups (3.8% each, p=0.9702). Another primary endpoint, non-fatal major cardiovascular events, tended to occur more often in the control group than in the candesartan group (9.2% vs. 12.5%, p=0.0985). In contrast, candesartan significantly reduced one of the pre-specified secondary endpoints: cardiovascular events that included non-fatal MI, uAP, and CHF (4.4% vs. 6.7%, p=0.0136). Furthermore, candesartan significantly reduced another secondary endpoint that included cardiovascular events and cardiovascular death (5.0% vs. 7.7%, p=0.0493).

CONCLUSIONS

The 4C trial showed that candesartan administered immediately after PCI with DESs did not improve the prognosis after the index procedure, but did reduce some cardiac-related events for 3 years.

Vascular restoration therapy and bioresorbable vascular scaffold

This article describes the evolution of minimally invasive intervention technologies for vascular restoration therapy from early-stage balloon angioplasty in 1970s, metallic bare metal stent and metallic drug-eluting stent technologies in 1990s and 2000s, to bioresorbable vascular scaffold (BVS) technology in large-scale development in recent years. The history, the current stage, the challenges and the future of BVS development are discussed in detail as the best available approach for vascular restoration therapy. The criteria of materials selection, design and processing principles of BVS, and the corresponding clinical trial results are also summarized in this article.

Myocardial infarction due to intracoronary embolization of percutaneous coronary intervention packaging

Intracoronary device loss is occasionally encountered and removal is commonly performed at the time of the procedure. We report a case of removal of a retained coronary balloon protective plastic tubing inadvertently left in the coronary artery for a month and associated with myocardial infarction. Optical coherence tomography was used to visualize the foreign body prior to removal with a snare. To our knowledge this is the first report of a removal of disposable packaging equipment after prolonged intracoronary dwell time.

Corrosion resistance improvement for 316L stainless steel coronary artery stents by trimethylsilane plasma nanocoatings

To improve their corrosion resistance and thus long-term biocompatibility, 316L stainless steel coronary artery stents were coated with trimethylsilane (TMS) plasma coatings of 20-25 nm in thickness. Both direct current (DC) and radio-frequency (RF) glow discharges were utilized for TMS plasma coatings and additional NH₃/O₂ plasma treatment to tailor the surface properties. X-ray photoelectron spectroscopy (XPS) was used to characterize the coating surface chemistry. It was found that both DC and RF TMS plasma coatings had Si- and C-rich composition, and the O- and N-contents on the surfaces were substantially increased after NH₃/O₂ plasma treatment. Surface contact angle measurements showed that DC TMS plasma nanocoating with NH₃/O₂ plasma treatment generated very hydrophilic surface. The corrosion resistance of TMS plasma coated stents was evaluated through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The potentiodynamic polarization demonstrated that the TMS plasma coated stents imparted higher corrosion potential and pitting potential, as well as lower corrosion current densities as compared with uncoated controls. The surface morphology of stents before and after potentiodynamic polarization testing was analyzed with scanning electron microscopy, which indicated less corrosion on coated stents than uncoated controls. It was also noted that, from EIS data, the hydrophobic TMS plasma nanocoatings showed stable impedance modulus at 0.1 Hz after 21 day immersion in an electrolyte solution. These results suggest improved corrosion resistance of the 316L stainless steel stents by TMS plasma nanocoatings and great promise in reducing and blocking metallic ions releasing into the bloodstream.

Degradable, drug-eluting stents: a new frontier for the treatment of coronary artery disease

This article reviews the clinical use of stents in the treatment of coronary artery disease and the rationale for the use of degradable, drug-eluting polymer stents. The authors note the challenges of using off-the-shelf polymers for the development of degradable stents, as well as the interplay between polymer properties and a functional stent design. Drug-eluting metal stents are the most significant advancement in the treatment of coronary artery disease, and have significantly reduced the occurrence of in-stent restenosis after placement. Some regard drug-eluting metal stents as the final technologic advancement in the treatment of coronary artery disease, others consider the future development of degradable, drug-eluting stents as the next logical step.

Bioresorbable drug-eluting magnesium-alloy scaffold for treatment of coronary artery disease

The introduction of metallic drug-eluting stents has reduced the risk of restenosis and widened the indications of percutaneous coronary intervention in treatment of coronary artery disease. However, this medical device can induce hypersensitive reaction that interferes with the endothelialization and healing process resulting in late persistent or acquired malapposition of the permanent metallic implant. Delayed endotheliaization and malapposition may lead to late and very late stent thrombosis. Bioresorbable scaffolds (BRS) have been introduced to potentially overcome these limitations, as they provide temporary scaffolding and then disappear, liberating the treated vessel from its cage. Magnesium is an essential mineral needed for a variety of physiological functions in the human body and its bioresorbable alloy has the strength-to-weight ratio comparable with that of strong aluminum alloys and alloy steels. The aim of this review is to present the new developments in Magnesium BRS technology, to describe its clinical application and to discuss the future prospects of this innovative therapy.

Angioplasty guided by intravascular ultrasound: meta-analysis of randomized clinical trials

BACKGROUND

The impact of intravascular ultrasound (IVUS) use on stenting has shown inconclusive results.

OBJECTIVE

Systematic review and meta-analysis of the impact of IVUS on stenting regarding the clinical and angiographic evolution.

METHODS

A search was performed in Medline/Pubmed, CENTRAL, Embase, Lilacs, Scopus and Web of Science databases. It included randomized clinical trials (RCTs) that evaluated the implantation of stents guided by IVUS, compared with those using angiography alone (ANGIO). The minimum follow-up duration was six months and the following outcomes were assessed: thrombosis, mortality, myocardial infarction, percutaneous and surgical revascularization, major adverse cardiovascular events (MACE) and restenosis. The binary outcomes were presented considering the number of events in each group; the estimates were generated by a random effects model, considering Mantel-Haenszel statistics as weighting agent and magnitude of effect for the relative risk (RR) with its respective 95% confidence interval (95%CI). Higgins I² test was used to quantify the consistency between the results of each study.

RESULTS

A total of 2,689 articles were evaluated, including 8 RCTs. There was a 27% reduction in angiographic restenosis (RR: 0.73, 95% CI: 0.54-0.97, I² = 51%) and statistically significant reduction in the rates of percutaneous revascularization and overall (RR: 0.88; 95% CI: 0.51 to 1.53, I² = 61%, RR: 0.73, 95% CI: 0.54 to 0.99, I² = 55%), with no statistical difference in surgical revascularization (RR: 0.95, 95% CI: 0.52-1.74, I² = 0%) in favor of IVUS vs. ANGIO. There were no differences regarding the other outcomes in the comparison between the two strategies.

CONCLUSION

Angioplasty with stenting guided by IVUS decreases the rates of restenosis and revascularization, with no impact on MACE, acute myocardial infarction, mortality or thrombosis outcomes.

Complications of coronary intervention: device embolisation, no-reflow, air embolism

The introduction of drug-eluting stents, better equipment, stronger antiplatelet drugs, and higher levels of operator experience has led to markedly improved patency rates for complex percutaneous coronary interventions (PCIs). The evolving techniques of contemporary PCI have been unable to completely eliminate complications. However, rigorous preventive measures pre-empt the appearance of complications. During traversal of severely diseased coronary arteries and manipulating equipment, particularly devices with detachable components, the opportunity for loss or embolisation of material in the coronary circulation presents itself. Device embolisation is associated with periprocedural myocardial infarction and emergent referral to surgery, particularly if the device is not retrieved. The coronary no-reflow phenomenon is a feared complication of PCI. It is associated with a worse prognosis and has been shown to be an independent predictor of death, myocardial infarction and impaired left ventricular function. Air embolism can be prevented by flushing of catheters during equipment exchanges.

High technology in medicine: lessons from cardiovascular innovations and future perspective

Four decades of innovations in the field of interventional cardiology are presented as an example for the great growth of high technology in medicine, side by side with the development of general technology and science. The field of percutaneous coronary intervention (PCI) was enabled by the development of X-ray systems, allowing us to view the pathology, and was critically dependent on courageous and imaginative physicians and scientists who developed percutaneous transluminal coronary angioplasty (PTCA), stents, and transarterial aortic valve replacement (TAVR). Today, outstanding research continues to progress, with stem cell research and IPC technologies presenting new challenges and yet taller mountains to climb. The rapid development we have witnessed was due to tight collaborations between clinical and academic institutions and industry. The combination of all these elements, with a proper mechanism to handle conflict of interest, is an essential linkage for any progress in this field. We will continue to see exponential growth of innovations and must be prepared with appropriate bodies to encourage such developments and to provide early-stage funding and support for novel ideas.

Will our training programs meet the challenges of increasingly complex endovascular aortic surgery?

It has been more than 2 decades since endovascular therapies appeared for the treatment of vascular disease. With each new enhancement in a therapeutic approach has come the demand for training to assure competence in the clinical setting. In the early days when the technology was relatively simple, training within the specific specialty through established training programs (eg, residencies, fellowships) was effective. However, today's endovascular treatment of complex aortic disease, as well as other vascular pathologies, is presenting demands that the current system cannot meet. New technologies will demand multispecialty collaboration, so current training programs must be altered if we are to meet the demands in education for future aortic interventions. This personal perspective reviews the evolution of endovascular therapy and the impact of product development's changing landscape on training. A new training paradigm must concentrate on centers of excellence with maximum flexibility to meet the needs and demands of our young trainees. It is vital that this approach be global, disease-focused, and linked to developments in epigenomics.

Approaches for dislodged stent retrieval during transradial percutaneous coronary interventions

Transradial percutaneous coronary intervention (PCI) has been associated with a lower incidence of major access site related complications. With the increased implementation of transradial approach in complex PCI, stent dislodgement is unavoidable in any interventionalists' career. Stent retrieval is different in a transradial approach as compared to a transfemoral approach because of the former's smaller arterial size. In this review, we outline the different stent retrieval techniques with considerations from transradial access.

Retrieval of a partially degloved stent strut during percutaneous coronary intervention

Although stent entrapment is a rare event during percutaneous coronary intervention, stent entrapment can cause stent breakage or loss, which results in fatal complications such as stent embolism or acute myocardial infarction. We report one case of stent entrapment that was successfully treated by a snare via a contralateral transfemoral approach.

Aspirin and platelet adenosine diphosphate receptor antagonists in acute coronary syndromes and percutaneous coronary intervention: role in therapy and strategies to overcome resistance

Platelet activation and aggregation are key components in the cascade of events causing thrombosis following plaque rupture. Antiplatelet therapy is essential in the treatment of patients with acute coronary syndromes (ACS) and for those requiring percutaneous coronary intervention (PCI). Aspirin (acetylsalicylic acid) is a well established antiplatelet therapy and is mandated for secondary prevention of cardiovascular events following ACS. In patients with ACS, the addition of clopidogrel to aspirin is more effective than aspirin alone. For patients undergoing PCI, dual antiplatelet therapy with aspirin and clopidogrel is warranted. Aspirin should be continued indefinitely after PCI. Pretreatment of patients with clopidogrel prior to PCI lowers the incidence of cardiovascular events, yet the optimum timing of drug administration and dose are still being investigated, as is the duration of therapy following PCI. Late-stent thrombosis with drug-eluting stents has pushed the recommendation for duration of clopidogrel therapy up to 1 year and perhaps beyond, in patients without risks for bleeding. The concepts of aspirin and clopidogrel resistance are important clinical questions. No uniform definition exists for aspirin or clopidogrel resistance. Measurements of resistance are often highly variable and do not necessarily correlate with clinical resistance. Noncompliance remains the most prominent mode of resistance. Screening of selected patient populations for resistance or pharmacologic intervention of those patients termed 'resistant' warrants further study.

Evaluating the safety of very short-term (10 days) dual antiplatelet therapy after Genous™ bio-engineered R stent™ implantation: the multicentre pilot Genous trial

AIMS

Percutaneous coronary stenting is synonymous with dual antiplatelet therapy, ranging from four weeks to lifelong. However, even short-term (four weeks) therapy with aspirin and thienopyridines is occasionally contraindicated. No study has ever appraised very short-term dual antiplatelet therapy after stenting. We thus aimed to exploit the pro-healing features of the Genous™ Bio-engineered R stent™ (Genous) (OrbusNeich Medical Technologies, Hong Kong, People's Republic of China) and evaluate the safety of a 10-day dual antiplatelet regimen after its implantation in up to 50 patients.

METHODS AND RESULTS

Forty-nine consecutive patients with de novo lesions located in vessels able to receive a 2.5 mm Genous stent were included. After stenting, they received lifelong aspirin plus clopidogrel for 10 days. The primary endpoint of the study was sudden cardiac death, myocardial infarction or angiographic evidence of stent thrombosis ascribable to the study stent. Almost 70% of patients effectively discontinued clopidogrel nine to 11 days after stenting. At three-month clinical follow-up, no patient had died or reached the primary endpoint (95%; confidence interval 0-7.3%). Repeat revascularisation occurred instead in three (6.1%[2.1-16.5%]), with target lesion revascularisation in two (4.1%[1.1-13.7%]).

CONCLUSIONS

Even very short-term dual antiplatelet therapy seems safe after coronary stenting with Genous in de novo coronary artery lesions located in secondary branch vessels. This preliminary exploratory study gives some support to planning a large trial to test the hypothesis of short dual antiplatelet therapy following Genous stent implantation.

Personalized antiplatelet therapy: review of the latest clinical evidence

P2Y12-ADP receptor antagonist use has been critical in the development of percutaneous coronary intervention, dramatically reducing the rate of early stent thrombosis. However, it recently was observed that a significant proportion of patients do not achieve optimal platelet reactivity inhibition after clopidogrel loading dose. The large interindividual variability in clopidogrel responsiveness is related to several factors, including the genetic polymorphism of hepatic cytochrome P450 2C19 (CYP2C19*2), which recently has been highlighted by a warning from the U.S. Food and Drug Administration. Of importance, patients exhibiting reduced clopidogrel metabolism and/or low clopidogrel responsiveness (ie, high on-treatment platelet reactivity) have an increased rate of thrombotic events after percutaneous coronary intervention. This review summarizes the current knowledge on this important clinical issue. While the future of genetic testing remains undetermined, several trials are underway to demonstrate the potential utility of platelet reactivity testing with P2Y12-ADP receptor antagonists.

[Decreasing incidence of stent thrombosis]

Stent thrombosis (ST) remains a major pitfall of stent implantation in contemporary percutaneous coronary intervention (PCI) leading to high rates of death and non-fatal myocardial infarction. Many predictors of ST have been reported worldwide but the strongest have to be highlighted regarding the catastrophic prognosis of such an event. Because platelet aggregation has a pivotal role in ST pathogenesis, the new antiplatelet regimens combining aspirin and P2Y12 receptor inhibitors have led to a remarkable decrease in the ST incidence, especially in the setting of acute coronary syndrome (ACS). In this article, our purpose is to review the evolution of ST incidence since first stent use in PCI. We will also overview the main predictors of ST focusing on ACS and clopidogrel low response.

Modifying clopidogrel maintenance doses according to vasodilator-stimulated phosphoprotein phosphorylation index improves clinical outcome in patients with clopidogrel resistance

BACKGROUND

Despite dual antiplatelet therapy, the rate of major adverse cardiovascular events (MACE) after percutaneous coronary intervention (PCI) remains high. Ex vivo tests of clopidogrel resistance can predict MACE after PCI. The purpose of this study is to evaluate the clinical impact of adjusting phosphorylation analysis in patients with clopidogrel resistance undergoing PCI.

HYPOTHESIS

We hypothesized that VASP-guided clopidogrel maintenance doses, compared to fixed doses, improved clinical outcome.

METHODS

This monocentric, prospective, randomized study was performed on 306 patients undergoing PCI. Patients were randomized to a control group (n = 156) and to a vasodilator-stimulated phosphoprotein (VASP)-guided group (n = 150). In the VASP-guided group, patients received adjusted maintenance doses of clopidogrel to obtain platelet reactivity index (PRI) of <50% during 1 year after PCI. The primary endpoint was the rate of MACE. The secondary endpoints were major and minor bleeding.

RESULTS

All patients completed the PCI procedure and 298 patients completed follow-up. The control and VASP-guided groups had similar demographic, clinical, and angiographic characteristics. In the VASP-guided group, PRI was significantly decreased (from 72.1% ± 11.4% to 27.7% ± 8.4%; P = 0.001) in 128 patients (87.1% of all participants). During the 1-year follow-up, 14 MACEs were recorded in the VASP-guided group and 30 MACEs were recorded in the control group (9.3% vs 20.4%, respectively; P = 0.008). There was no difference in the rate of major and minor bleeding in the VASP-guided group compared with the control group (12.9% vs 16.6%; P = 0.06).

CONCLUSIONS

Modifying clopidogrel maintenance doses according to platelet reactivity monitoring decreases the rate of MACE after PCI without increasing bleeding in patients with clopidogrel resistance during 1-year follow-up.

In vitro and in vivo studies of local arterial gene delivery and transfection using lipopolyplexes-embedded stents

Gene-eluting stents can have profound impact in the treatment of coronary restenosis, especially when the encoded protein can re-endothelialize the arterial lumen. In this study, we have examined gene delivery in vitro and in vivo using poly(beta-amino ester) (PbAE) precondensed plasmid DNA-containing cationic liposomes or lipopolyplexes (LPP) immobilized on stainless steel meshes and stents using gelatin coatings. In vitro studies using LPP-immobilized on 50 mm round meshes using type A and B gelatin coatings showed that LPP were efficiently internalized in human aortic smooth muscle cells (SMC) over time, leading to green fluorescent protein (GFP) expression. Type B gelatin coating was found to be more effective in intracellular delivery and transgene expression efficiency and, as such, was used for stent coating. In vivo studies, carried out in iliac artery restenosis model in New Zealand white rabbits, also showed GFP expression in arterial tissues after 24 h of implantation. Based on these encouraging preliminary results, LPP-based formulations can serve as a safe and effective nonviral gene delivery system for effective treatment of coronary restenosis.

Enhancement of fibrinolytic activity in vascular endothelial cells by heterologous expression of adenine nucleotide translocase-1

The fibrinolytic activity of blood is regulated by expressing tissue-type plasminogen activator (t-PA) and its specific inhibitor, type-1 plasminogen activator inhibitor (PAI-1), from vascular endothelial cells. Since t-PA is a major plasminogen activator in blood, it is considered that the binding protein for t-PA, which exists on endothelial cell membrane, immobilizes t-PA on the surface of endothelial cells and enhances their antithrombotic property. Recently, we have found a new t-PA binding protein in endothelial cells. Its amino acid sequence has matched that of human adenine nucleotide translocase-1 (ANT1). The aims of this study are to confirm the binding of t-PA to ANT1, and to clarify the effect of ANT1 on fibrinolytic activity around endothelial cells. ANT1 is prepared from recombinant glutathione S-transferase (GST)-ANT1 fusion protein, and reveals t-PA binding activity in a ligand blot assay. In addition, ANT1 is exclusively expressed on endothelial cell membrane by using pDisplay vector. Interaction of t-PA with ANT1, which is expressed on the surface of endothelial cells, is confirmed by IAsys binding analysis and chromogenic assay. The heterologous expression of ANT1 on endothelial cell membrane enhances the t-PA binding ability of endothelial cells and the effect of ANT1 expression on fibrinolytic activity is demonstrated by increasing t-PA-catalyzed plasminogen activation. These results suggest that a novel t-PA-binding protein, ANT1, may concentrate t-PA on the surface of cells and enhance fibrinolytic properties around endothelial cells; therefore, ANT1 can be a powerful tool for regulating the plasminogen activation system in the vessel.