Mechanisms of restenosis after coronary intervention: difference between plain old balloon angioplasty and stenting

Is it time for a retinoic acid-eluting stent or retinoic acid-coated balloon? Insights from experimental studies of systemic and local delivery of retinoids

Although the incidence of restenosis and stent thrombosis has substantially declined during the last decades, they still constitute the two major causes of stent failure. These complications are partially attributed to the currently used cytostatic drugs, which can cause local inflammation, delay or prevent re-endothelialization and essentially cause arterial cell toxicity. Retinoic acid (RA), a vitamin A (retinol) derivative, is a naturally occurring substance used for the treatment of cell proliferation disorders. The agent has pleiotropic effects on vascular smooth muscle cells and macrophages: it influences the proliferation, migration, and transition of smooth muscle cells to other cell types and modulates macrophage activation. These observations are supported by accumulated evidence from in vitro and in vivo experiments. In addition, systemic and topical administration of RA can decrease the development of atherosclerotic plaques and reduce or inhibit restenosis after vascular injury (caused by embolectomy, balloon catheters, or ligation of arteries) in various experimental models. Recently, an RA-drug eluting stent (DES) has been tested in an animal model. In this review, we explore the effects of RA in atherosclerosis and the potential of the local delivery of RA through an RA-DES or RA-coated balloon for targeted therapeutic percutaneous vascular interventions. Despite promising published results, further experimental study is warranted to examine the safety and efficacy of RA-eluting devices in vascular artery disease.

Safety and Efficacy of an Innovative Everolimus-Coated Balloon in a Swine Coronary Artery Model

BACKGROUND

Drug-coated balloons have been used as a non-stenting treatment in coronary and peripheral artery disease. Until recently, only sirolimus- and paclitaxel-coated balloons have been investigated in clinical trials. We evaluated the safety and efficacy of an innovative everolimus-coated balloon (ECB) in a swine coronary artery model.

METHODS

thirty-two swine coronary arteries were prepared through dilatation with a non-coated angioplasty balloon in a closed-chest model. During a period of 90 days, the following four groups (four animals per group, two coronary arteries per animal) were compared for safety and efficacy: A, Rontis ECB with 2.5 μg/mm2 of drug per balloon surface; B, Rontis ECB with 7.5 μg/mm2; C, Rontis Europa Ultra bare balloon; and D, Magic Touch, Concept Medical, sirolimus-coated balloon with a drug load of 1.3 μg/mm2.

RESULTS

Differences in local biological effects (arterial reaction scores) and surface of intimal area (mm2) were not statistically significant between the treatment groups. Numerically, group A showed the lowest intimal area and intimal mean thickness, while group B showed the lowest stenosis among all groups.

CONCLUSIONS

ECB was safe and effective in a porcine coronary artery model. The dose of everolimus may play a role in the biocompatibility of the balloon.

Adaptation of Vascular Smooth Muscle Cell to Degradable Metal Stent Implantation

Iron-, magnesium-, or zinc-based metal vessel stents support vessel expansion at the period early after implantation and degrade away after vascular reconstruction, eliminating the side effects due to the long stay of stent implants in the body and the risks of restenosis and neoatherosclerosis. However, emerging evidence has indicated that their degradation alters the vascular microenvironment and induces adaptive responses of surrounding vessel cells, especially vascular smooth muscle cells (VSMCs). VSMCs are highly flexible cells that actively alter their phenotype in response to the stenting, similarly to what they do during all stages of atherosclerosis pathology, which significantly influences stent performance. This Review discusses how biodegradable metal stents modify vascular conditions and how VSMCs respond to various chemical, biological, and physical signals attributable to stent implantation. The focus is placed on the phenotypic adaptation of VSMCs and the clinical complications, which highlight the importance of VSMC transformation in future stent design.

Long-term Outcomes for Drug-eluting Balloons versus Drug-eluting Stents in the Treatment of Small Vessel Coronary Artery Disease: A Systematic Review and Meta-analysis

Background: This systematic review and meta-analysis compares long-term outcomes follow-up data comparing drug-eluting balloons (DEBs) and drug-eluting stents (DESs) in interventional treatment of small coronary artery disease (<3 mm). Methods: A systematic review was undertaken along with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome was 1-3-year performance of DEB versus DES in major adverse cardiac events. Secondary outcomes include all-cause mortality, MI, cardiac death, vessel thrombosis, major bleeding, target vessel revascularisation and target lesion revascularisation. Two independent reviewers extracted data. All outcomes used the Mantel-Haenszel and random effects models. ORs are presented with a 95% CI. Results: Of 4,661 articles, four randomised control trials were included (1,414 patients). DEBs demonstrated reduced rates of non-fatal MI at 1 year (OR 0.44; 95% CI [0.2-0.94]), and BASKET-SMALL 2 reported a significant reduction in 2-year bleeding rates (OR 0.3; 95% CI [0.1-0.91]). There was no significant difference in all other outcomes. Conclusion: Long-term follow-up of DEB and DES use in small coronary arteries demonstrates DEBs be comparable with DESs in all outcomes at 1, 2 and 3 years of follow-up. A significant reduction was found in rates of non-fatal MI at 1 year in the DEB arm, and a reduction in major bleeding episodes at 2 years in the BASKET-SMALL 2 trial. These data highlight the potential long-term utility of novel DEBs in small coronary artery disease revascularisation.

One year clinical outcomes of Rutherford 6 chronic limb threatening ischemia patients undergoing lower limb endovascular revascularisation from Singapore

Background

Percutaneous transluminal angioplasty (PTA) is widely used as a first-line revascularisation option in patients with chronic limb threatening ischemia (CLTI). This study aimed to evaluate the short-term endovascular revascularisation treatment outcomes of a cohort of Rutherford 6 (R6) CLTI patients, from a multi-ethnic Asian population in Singapore.

Patients with R6 CLTI who underwent endovascular revascularisation from June 2019 to February 2020 at Singapore General Hospital, a tertiary vascular centre in Singapore, were included and followed up for one year. Primary outcome measures included number and type of reinterventions required, 3-, 6- and 12-month mortality, 6- and 12-month amputation free survival (AFS), wound healing success and changes in Rutherford staging after 3, 6 and 12 months.

Results

Two hundred fifty-five procedures were performed on 86 patients, of whom 78 (90.7%) were diabetics, 54 (62.8%) had coronary artery disease (CAD) and 54 (62.8%) had chronic kidney disease (CKD). 42 patients (48.8%) required reintervention within 6 months. Multivariate analysis revealed that the presence of CAD was a significant independent predictor for reintervention. Mortality was 15.1%, 20.9% and 33.7% at 3, 6 and 12 months respectively. AFS was 64.0% and 49.4% at 6 and 12 months. Inability to ambulate, congestive heart failure (CHF), dysrhythmia and CKD were significant independent predictors of lower 12-month AFS.

Conclusions

PTA for R6 CLTI patients was associated with relatively high mortality and reintervention rates at one year. CAD was an independent predictor of reintervention. More research is required to help risk stratify which CLTI patients would benefit from an endovascular-first approach versus conservative treatment or an immediate major lower extremity amputation policy.

Endothelium-targeted delivery of PPARδ by adeno-associated virus serotype 1 ameliorates vascular injury induced by hindlimb ischemia in obese mice

Diabetic vasculopathy is a major health problem worldwide. Peripheral arterial disease (PAD), and in its severe form, critical limb ischemia is a major form of diabetic vasculopathy with limited treatment options. Existing literature suggested an important role of PPARδ in vascular homeostasis. It remains elusive for using PPARδ as a potential therapeutic target due to mostly the side effects of PPARδ agonists. To explore the roles of PPARδ in endothelial homeostasis, endothelial cell (EC) selective Ppard knockout and controlled mice were subjected to hindlimb ischemia (HLI) injury. The muscle ECs were sorted for single-cell RNA sequencing (scRNA-seq) analysis. HLI was also performed in high fat diet (HFD)-induced obese mice to examine the function of PPARδ in obese mice with delayed vascular repair. Adeno-associated virus type 1 (AAV1) carrying ICAM2 promoter to target endothelium for overexpressing PPARδ was injected into the injured muscles of normal chow- and HFD-fed obese mice before HLI surgery was performed. scRNA-seq analysis of ECs in ischemic muscles revealed a pivotal role of PPARδ in endothelial homeostasis. PPARδ expression was diminished both after HLI injury, and also in obese mice, which showed further delayed vascular repair. Endothelium-targeted delivery of PPARδ by AAV1 improved perfusion recovery, increased capillary density, restored endothelial integrity, suppressed vascular inflammation, and promoted muscle regeneration in ischemic hindlimbs of both lean and obese mice. Our study indicated the effectiveness of endothelium-targeted PPARδ overexpression for restoring functional vasculature after ischemic injury, which might be a promising option of gene therapy to treat PAD and CLI.

Outcomes of Lower Extremity Endovascular Revascularization: Potential Predictors and Prevention Strategies

Peripheral artery disease (PAD) is a manifestation of atherosclerosis, which may affect arteries of the lower extremities. The most dangerous PAD complication is chronic limb-threatening ischemia (CLTI). Without revascularization, CLTI often causes limb loss. However, neither open surgical revascularization nor endovascular treatment (EVT) ensure long-term success and freedom from restenosis and revascularization failure. In recent years, EVT has gained growing acceptance among all vascular specialties, becoming the primary approach of revascularization in patients with CLTI. In clinical practice, different clinical outcomes after EVT in patients with similar comorbidities undergoing the same procedure (in terms of revascularization technique and localization of the disease) cause unsolved issues that need to be addressed. Nowadays, risk management of revascularization failure is one of the major challenges in the vascular field. The aim of this literature review is to identify potential predictors for lower extremity endovascular revascularization outcomes and possible prevention strategies.

Feasibility and safety of the new coronary noncompliant balloon catheter River NC®

Aim: In this preliminary study, we aimed to confirm the clinical utility and safety of the new noncompliant balloon catheter River NC (Balton, Poland). Materials & methods: The primary study endpoint was to verify balloon diameters calculated in quantitative coronary angiography (QCA) to diameters prespecified by the manufacturer and obtained at given pressures in subjects undergoing percutaneous coronary interventions. Results: Forty-two subjects were enrolled (73.8% multivessel disease; 40.5% type B1 lesions; 100% device success). No clinically significant differences between expected balloon diameters and QCA were registered in predilatation (2.36 ± 0.11 mm vs. 2.43 ± 0.07 mm) and postdilatation (3.18 ± 0.19 mm vs. 3.21 ± 0.31 mm). Conclusions: Our study results suggest that the River NC balloon is effective and safe. In the QCA evaluation, River NC balloon obtained prespecified diameters and lengths at applied pressures. Study registration: Office for Registration of Medicinal Products, Medical Devices and Biocidal Products (UR.D.WM.DNB.109.2019).

A risk predictor of restenosis after superficial femoral artery stent implantation: relevance of mean platelet volume

Background

To investigate the relationship between an increase in the pre- and post-operative mean platelet volume (MPV) and superficial femoral artery in-stent restenosis (ISR) rate.

Methods and results

We recruited patients that underwent superficial femoral artery stenting for lower extremity arteriosclerosis obliterans at our hospital from March 2015 to March 2018. All patients gave venous blood three days before and following implantation. Doppler ultrasound, computed tomography angiography or digital subtraction angiography were used for regular follow-up examination. Logistic regression was used to identify predictors of ISR after superficial femoral artery stenting. We enrolled 173 patients, of which 34 (19.6%) were determined as having ISR for a mean of 8.9 ± 2.7 months (3–12 months). Neutrophil count, neutrophil ratio, lymphocyte ratio and platelet count pre-implantation, and platelet count and MPV after stent implantation, and the pre- and post-operative mean platelet volume difference (MPVD) and mean platelet volume difference ratio (MPVDR) were all statistically different when comparing the ISR and non-restenosis groups (p < 0.05). A positive correlation was found for post-operative MPV and presence of ISR (r = 0.58; P < 0.001). A MPVD not less than 1.5 fL was associated with an odds ratio of 9.17 (95% CI [3.76 to 22.35]; P < 0.001) for presence of ISR. A MPVDR of not less than 17.9% was associated with an odds ratio of 7.68 (95% CI [3.19 to 18.49]; P < 0.001) for occurrence of ISR.

Conclusions

An increase in pre- and post-operative MPV was correlated with the occurrence of superficial femoral artery ISR.

Association of Elevated Plasma Homocysteine Level with Restenosis and Clinical Outcomes After Percutaneous Coronary Interventions: a Systemic Review and Meta-analysis

PURPOSE

We conducted this systemic review and meta-analysis to investigate the association between elevated plasma homocysteine (Hcy) levels and recurrent restenosis and clinical outcomes after percutaneous coronary intervention (PCI).

METHODS

PubMed, EMBASE, and Web of Science were systematically searched prior to May 2018. Studies evaluating the association between plasma Hcy levels and the occurrence of restenosis, major adverse cardiac events (MACE), all-cause mortality, cardiac death, non-fatal myocardial infarction (MI), and target lesion revascularization were identified.

RESULTS

A total of 19 articles with 4340 participants were identified. Higher Hcy levels were not associated with an increased risk of restenosis (relative risk (RR) = 1.10, 95% CI 0.90-1.33). Hcy levels in the restenosis group were not significantly higher than in the non-restenosis group (weighted mean difference = 0.70, 95% CI - 0.23-1.63). Subgroup analysis revealed that higher Hcy levels were not associated with restenosis after stenting but appeared to increase the risk of restenosis after angioplasty. Elevated Hcy levels increased the risk of all-cause mortality by an average of 3.19-fold (RR = 3.19, 95% CI 1.90-5.34, P = 0.000), the risk of MACE by 1.51-fold (RR = 1.51, 95% CI 1.23-1.85, P = 0.000), and the risk of cardiac death by 2.76-fold (RR = 2.76, 95% CI 1.44-5.32, P = 0.000) but appeared not to increase the risk of non-fatal MI (RR = 1.36, 95% CI 0.89-2.09).

CONCLUSIONS

Our meta-analysis suggests that although there is no clear association between higher Hcy levels and restenosis following stent implantation, higher Hcy levels appeared to increase the risk of restenosis after coronary angioplasty and also increased the risk of all-cause mortality, MACE, and cardiac death after PCI.

REGISTRATION DETAILS

The protocol of this meta-analysis was registered on PROSPERO (CRD42018096466). ( http://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42018096466 ).

Deep Learning in Personalization of Cardiovascular Stents

Deep learning (DL) application has demonstrated its enormous potential in accomplishing biomedical tasks, such as vessel segmentation, brain visualization, and speech recognition. This review article has mainly covered recent advances in the principles of DL algorithms, existing DL software, and designing strategies of DL models. Latest progresses in cardiovascular devices, especially DL-based cardiovascular stent used for angioplasty, differential and advanced diagnostic means, and the treatment outcomes involved with coronary artery disease (CAD), are discussed. Also presented is DL-based discovery of new materials and future medical technologies that will facilitate the development of tailored and personalized treatment strategies by identifying and forecasting individual impending risks of cardiovascular diseases.

Avβ3 single-stranded DNA aptamer attenuates vascular restenosis via Ras-PI3K/MAPK pathway in rats after percutaneous transluminal coronary angioplasty

Our aim was to investigate the effect of avβ3 single-stranded DNA aptamer (avβ3 ssDNA) on vascular restenosis in rats after percutaneous transluminal coronary angioplasty (PTCA) via the Ras-PI3K/MAPK pathway. Sixty Sprague-Dawley rats were randomly divided into six groups: sham-operated, PTCA, PTCA+cilengitide (18 mg/kg, n = 8), and avβ3 ssDNA treatment at 50, 100, and 200 μg/kg. Hematoxylin-eosin staining was performed to evaluate the successful establishment of the PTCA model and to assess the degree of intimal hyperplasia. Immunofluorescence and in situ hybridization were carried out to observe the level of avβ3. Immunohistochemistry was used to detect the expression of E-cadherin, N-cadherin, α-smooth muscle actin (α-SMA), angiotensin 1 (ANG1), and ANG2. The expression of osteopontin (OPN), focal adhesion kinase (FAK), Ras, mitogen-activated protein kinase (MAPK), phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K), signal transducer and activator of transcription 1 (STAT1), and GTPase was observed by the western blot and quantitative reverse transcription polymerase chain reaction. Compared with rats subjected to PTCA only, those treated with avβ3 ssDNA showed significantly decreased vascular occlusion rate (P < .05). The protein expression of avβ3, OPN, p-FAK, ANG2, and E-cadherin was significantly increased by avβ3 ssDNA (P < .05), while the levels of ANG1, α-SMA, N-cadherin Ras, MAPK, PI3K, STAT1, and GTPase were significantly decreased (P < .05). Avβ3 ssDNA reduced the proliferation, migration, epithelial-mesenchymal transition, and vascular remodeling of vascular smooth muscle cells, and the mechanism may be related to the Ras-PI3K/MAPK pathway.

Ginsenoside Rg1 as an Effective Regulator of Mesenchymal Stem Cells

Recently, breakthroughs have been made in the use of mesenchymal stem cells (MSCs) to treat various diseases. Several stem cell types have been authorized as drugs by the European Medicines Agency and the U.S. Food and Drug Administration. The Chinese official document “Notification of the management of stem cell clinical research (trial)” was also published in August 2015. Currently, China has approved 106 official stem cell clinical research filing agencies and 62 clinical research projects, which are mostly focused on MSC therapy. Hence, the optimization and development of stem cell drugs is imperative. During this process, maximizing MSC expansion, minimizing cell loss during MSC transplantation, improving the homing rate, precisely regulating the differentiation of MSCs, and reducing MSC senescence and apoptosis are major issues in MSC preclinical research. Similar to artemisinin extracted from the stems and leaves of Artemisia annua, ginsenoside Rg1 (Rg1) is purified from the root or stem of ginseng. In the human body, Rg1 regulates organ function, which is inseparable from its regulation of adult stem cells. Rg1 treatment may effectively regulate the proliferation, differentiation, senescence, and apoptosis of MSCs in different microenvironments in vitro or in vivo. In this review, we discuss recent advances in understanding the effect of Rg1 on MSCs and describe the issues that must be addressed and prospects regarding Rg1 regulation of MSCs in preclinical or clinical studies.

A Review of Antithrombotic Treatment in Critical Limb Ischemia After Endovascular Intervention

Endovascular intervention is often used to treat critical limb ischemia (CLI). Post-intervention treatment with antiplatelet and/or anticoagulant therapy has reduced morbidity and mortality due to cardiovascular complications. The purpose of this review is to shed light on the various pharmacologic treatment protocols for treating CLI following endovascular procedures. We reviewed the literature comparing outcomes after antithrombotic treatment for patients with CLI. We characterized antithrombotic therapies into three categories: (1) mono-antiplatelet therapy (MAPT) vs. dual antiplatelet therapy (DAPT), (2) MAPT vs. antiplatelet (AP) + anticoagulant (AC) therapy, and (3) AC vs. AP + AC therapy. Relevant results and statistics were extracted to determine differences in the rates of the following outcomes: (1) re-stenosis, (2) occlusion, (3) target limb revascularization (TLR), (4) major amputation, (5) major adverse cardiac events, (6) all-cause death, and (7) bleeding. Studies suggest that DAPT reduces post-surgical restenosis, TLR, and amputation for diabetic patients, without increasing major bleeding incidences, compared to MAPT. Also, AP + AC therapy provides overall superior efficacy, with no difference in bleeding incidences, compared to antiplatelet alone. Additionally, the effects were significant for restenosis, limb salvage, survival rates, and cumulative rate of above ankle amputation or death. These results suggest that treatment with DAPT and AP + AC might provide better outcomes than MAPT following the endovascular intervention for CLI, and that the ideal treatment may be related to the condition of the individual patient. However, the studies were few and heterogenous with small patient populations. Therefore, further large controlled studies are warranted to confirm these outcomes.

Drug-Coated Balloon-Only Percutaneous Coronary Intervention for the Treatment of De Novo Coronary Artery Disease: A Systematic Review

Percutaneous coronary intervention (PCI) with a drug coated balloon (DCB) is a novel treatment which seeks to acutely dilate a coronary stenosis and deliver an anti-proliferative drug to the vessel wall (reducing the risk of re-stenosis), without implanting a drug eluting stent (DES). In this study, we performed a systematic review of stentless DCB-only angioplasty in de novo coronary artery disease. We identified 41 studies examining the effects of DCB-only PCI in a variety of clinical scenarios including small vessels, bifurcations, calcified lesions, and primary PCI. DCB-only PCI appears to be associated with comparable clinical outcomes to DESs and superior angiographic outcomes to plain-old balloon angioplasty. Although current data are promising, there is still a need for further long-term randomized control trial data comparing a DCB-only approach specifically against a second- or third-generation DES. A 4-week period of dual antiplatelet therapy provides a real advantage for the DCB-only PCI approach, which is not possible with most DESs. Since rates of adverse clinical outcomes are very low for all PCI procedures attention should be turned to the development of robust endpoints with which to compare DCB-only PCI approaches to the standard treatment with a DES.

Guidance Molecules in Vascular Smooth Muscle

Several highly conserved families of guidance molecules, including ephrins, Semaphorins, Netrins, and Slits, play conserved and distinct roles in tissue remodeling during tissue patterning and disease pathogenesis. Primarily, these guidance molecules function as either secreted or surface-bound ligands that interact with their receptors to activate a variety of downstream effects, including cell contractility, migration, adhesion, proliferation, and inflammation. Vascular smooth muscle cells, contractile cells comprising the medial layer of the vessel wall and deriving from the mural population, regulate vascular tone and blood pressure. While capillaries lack a medial layer of vascular smooth muscle, mural-derived pericytes contribute similarly to capillary tone to regulate blood flow in various tissues. Furthermore, pericyte coverage is critical in vascular development, as perturbations disrupt vascular permeability and viability. During cardiovascular disease, smooth muscle cells play a more dynamic role in which suppression of contractile markers, enhanced proliferation, and migration lead to the progression of aberrant vascular remodeling. Since many types of guidance molecules are expressed in vascular smooth muscle and pericytes, these may contribute to blood vessel formation and aberrant remodeling during vascular disease. While vascular development is a large focus of the existing literature, studies emerged to address post-developmental roles for guidance molecules in pathology and are of interest as novel therapeutic targets. In this review, we will discuss the roles of guidance molecules in vascular smooth muscle and pericyte function in development and disease.

The Society for Vascular Surgery practice guidelines on follow-up after vascular surgery arterial procedures

Although follow-up after open surgical and endovascular procedures is generally regarded as an important part of the care provided by vascular surgeons, there are no detailed or comprehensive guidelines that specify the optimal approaches with regard to testing methods, indications for reintervention, and follow-up intervals. To provide guidance to the vascular surgeon, the Clinical Practice Council of the Society for Vascular Surgery appointed an expert panel and a methodologist to review the current clinical evidence and to develop recommendations for follow-up after vascular surgery procedures. For those procedures for which high-quality evidence was not available, recommendations were based on observational studies, committee consensus, and indirect evidence. Recognizing that there are numerous published reports on the role of duplex ultrasound for surveillance of infrainguinal vein bypass grafts, the Society commissioned a systematic review and meta-analysis on this topic. The panel classified the strength of each recommendation and the corresponding quality of evidence on the basis of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system: recommendations were graded either strong or weak, and the quality of evidence was graded high, moderate, or low. The resulting recommendations represent a wide variety of open surgical and endovascular procedures involving the extracranial carotid artery, thoracic and abdominal aorta, mesenteric and renal arteries, and lower extremity arterial revascularization. The panel also identified many areas in which there was a lack of high-quality evidence to support their recommendations. This suggests that there are opportunities for further clinical research on testing methods, threshold criteria, and the role of surveillance as well as on the modes of failure and indications for reintervention after vascular surgery procedures.

Endovascular Stents: Market Vigilance and Risk Factors

With the aim of enhancing the safety and reliability level of coronary stents, we analyzed data collected from accident reports drawn from the MAUDE database (Manufacturer and User Facility Device Experience Database) of the FDA from 1996 to 2000. This analysis allowed us to highlight problems related to the use of coronary stents by means of the analysis of these reports at different levels, beginning from the causes that can lead to a certain type of accident up to the possible complication related to that event. Moreover we analyzed the procedure outcomes in terms of stent position inside the patient's body and the possible therapies adopted to solve the problems. The results showed that the most probable event that can lead to an accident is the stent separation from the balloon which, alone, turns up in a number of cases equal to the sum of all the others.

This result highlights the importance of the technical skill of the operators accomplished by special training and of the importance of clarity and completeness in the instructions for the use of the device. Another critical point is the reliability of the device which must guarantee an adequate safety level when it is used according to the instructions.

Effects of angiotensin receptor blockers on neointimal characteristics in angina patients requiring stent implantation: optical coherence tomography analysis

BACKGROUND

Angiotensin receptor blockers (ARBs) are known for its anti-inflammatory and anti-proliferative effects. The aim of the study was to evaluate long-term effects of ARBs on morphologic characteristics of stent restenosis in patients with coronary artery disease requiring stent implantation by optical coherence tomography (OCT).

METHODS

Patients with coronary artery disease having history of drug-eluting stent implantation (n = 407) were analyzed on the basis of ARB therapy as the ARB group (n = 162) and the non-ARB group (n = 245). Neointimal characterizations were performed at lesions with diameter stenosis >30% with OCT in each group. Major adverse cardiovascular events (MACEs), lumen area, stent area, neointimal area, neointimal thickness, nonapposed struts, uncovered struts, and intraluminal mass between two groups were also observed.

RESULTS

More patients in the ARB group revealed homogeneous and layered neointimal pattern (44.9% vs. 35.6%, P < 0.001, and 16.8% vs. 10.6%, P < 0.001, respectively), and whereas patients in the non-ARB group revealed heterogeneous neointimal pattern (1.1% vs. 7.6%, P < 0.001). Mean neointimal area (1.09 ± 1.00 mm2 vs. 1.38 ± 1.24 mm2) and mean neointimal thickness (140.6 ± 112.0 μm vs. 189.6 ± 423.1 μm) with OCT were smaller in the ARB group when compared to the non-ARB group. Percentage of covered stents was significantly higher in the ARB group when compared to the Non-ARB group (97.3% vs. 92.6%, P = 0.015). Other factors such as follow-up % diameter stenosis, late lumen loss, binary restenosis, MACEs, various neointimal characteristics analyzed by image analyzing software did not show significant differences.

CONCLUSION

The use of ARBs after drug-eluting stent implantation demonstrated difference in neointimal characteristics, less amount of neointimal area and fewer number of uncovered stent struts during the follow-up OCT, indicating the anti-proliferative and anti-inflammatory effects of ARBs.

Regulation of endothelial migration and proliferation by ephrin-A1

Endothelial migration and proliferation are fundamental processes in angiogenesis and wound healing of injured or inflamed vessels. The present study aimed to investigate the regulation of the Eph/ephrin-system during endothelial proliferation and the impact of the ligand ephrin-A1 on proliferation and migration of human umbilical venous (HUVEC) and arterial endothelial cells (HUAEC). Endothelial cells that underwent contact inhibition showed a massive induction of ephrin-A1. In contrast, an injury to a confluent endothelial layer, associated with induction of migration and proliferation, showed reduced ephrin-A1 levels. In addition, reducing ephrin-A1 expression by siRNA led to increased proliferation, whereas the overexpression of ephrin-A1 led to decreased proliferative activity. Due to the fact that wound healing is a combination of proliferation and migration, migration was investigated in detail. First, classical wound-healing assays showed increased wound closure in both ephrin-A1 silenced and overexpressing cells. Live-cell imaging enlightened the underlying differences. Silencing of ephrin-A1 led to a faster but more disorientated migration. In contrast, ephrin-A1 overexpression did not influence velocity of the cells, but the migration was more directed in comparison to the controls. Additional analysis of EphA2-silenced cells showed similar results in terms of proliferation and migration compared to ephrin-A1 silenced cells. Detailed analysis of EphA2 phosphorylation on ligand-dependent phospho-site (Y588) and autonomous activation site (S897) revealed a distinct phosphorylation pattern. Furthermore, the endothelial cells ceased to migrate when they came in contact with an ephrin-A1 coated surface. Using a baculoviral-mediated expression system, ephrin-A1 silencing and overexpression was shown to modulate the formation of focal adhesions. This implicates that ephrin-A1 is involved in changes of the actin cytoskeleton which explains the alterations in migratory actions, at least in part. In conclusion, ephrin-A1 expression is regulated by cellular density and is itself a critical determinant of endothelial proliferation. According to current knowledge, ephrin-A1 seems to be remarkably involved in elementary processes of endothelial migration like cellular polarization, migratory direction and speed. These data support the notion that ephrin-A1 plays a pivotal role in basal mechanisms of re-endothelialization.

Stent coverage and neointimal proliferation in bare metal stents postdilated with a Paclitaxel-eluting balloon versus everolimus-eluting stents: prospective randomized study using optical coherence tomography at 6-month follow-up

BACKGROUND

In this randomized trial, strut coverage and neointimal proliferation of a therapy of bare metal stents (BMSs) postdilated with the paclitaxel drug-eluting balloon (DEB) was compared with everolimus drug-eluting stents (DESs) at 6-month follow-up using optical coherence tomography. We hypothesized sufficient stent coverage at follow-up.

METHODS AND RESULTS

A total of 105 lesions in 90 patients were treated with either XIENCE V DES (n=51) or BMS postdilated with the SeQuent Please DEB (n=54). At follow-up, comparable results on the primary optical coherence tomography end point (percentage uncovered struts 5.64±9.65% in BMS+DEB versus 4.93±9.29% in DES; P=0.366) were found. Thus, BMS+DEB achieved the prespecified noninferiority margin of 5% uncovered struts versus DES (difference between treatment means, 0.71%; one-sided upper 95% confidence interval, 4.14%; noninferiority P=0.04). Optical coherence tomography analysis showed significantly more global neointimal proliferation in the BMS+DEB group (15.7±7.8 versus 11.0±5.2 mm(3) proliferation volume/cm stent length; P=0.002). No significant focal in-stent stenosis analyzed with angiography (percentage diameter stenosis at follow-up, 22.8±11.9 versus 16.9±10.4; P=0.014) and optical coherence tomography (peak local area stenosis, 39.5±13.8% versus 36.8±15.6%; P=0.409) was found.

CONCLUSIONS

Good stent strut coverage of >94% was found in both therapy groups. Despite greater suppression of global neointimal growth in DES, both DES and BMS+DEB effectively prevented clinically relevant focal restenosis at 6-month follow-up.

CLINICAL TRIAL REGISTRATION URL

http://www.clinicaltrials.gov. Unique identifier: NCT01056744.

Angiotensin II type 1 receptor blockers suppress neointimal hyperplasia after stent implantation in carotid arteries of hypercholesterolemic rabbits

OBJECTIVES

The purpose of this study was to examine whether oral administration of an angiotensin II type 1 receptor blocker (ARB) inhibited in-stent neointimal hyperplasia in carotid arteries of hypercholesterolemic rabbits.

METHODS

Eleven male New Zealand white rabbits were subjected to endothelial injuries of the right common carotid arteries using a balloon catheter and then received chow containing 1% cholesterol for 6 weeks. A balloon-expandable stainless steel stent was subsequently inserted at the injured sites of the arteries. After stenting, five rabbits were randomly treated with an oral ARB, candesartan cilexetil (5 mg/kg per day orally), while the remaining six rabbits acted as untreated controls. Four weeks after the implantation, the rabbits were killed, followed by collection of the arteries including the stents. After careful removal of the stents, tissue sections were prepared and analyzed by morphometric and immunohistochemical methods.

RESULTS

The mean thickness of the neointima was 53.6 ± 17.0 μm in the ARB-treated group, which was significantly reduced compared to 95.9 ± 16.7 μm in the control group (P = 0.0012). Immunohistochemistry showed a decrease in accumulation of macrophages and tenascin-C expression in the arterial wall in the ARB-treated animals.

DISCUSSION

This study suggested that systemic administration of an ARB suppressed neointimal hyperplasia in the carotid artery following stent implantation by the anti-inflammatory effects, although the animal cohort tested was rather small. This finding implies that ARBs may be useful and practical agents for protection against in-stent restenosis in humans, and warrants further basic and clinical studies.

Evolving management of patients treated by drug-eluting stent: prevention of late events

SUMMARY

Drug eluting stents (DES) were introduced in clinical practice to overcome the problem of in-stent restenosis (ISR) that limited the overall efficacy of percutaneous coronary revascularization with bare metal stent (BMS). Long-term outcome data confirm a sustained benefit of DES as compared with BMS. However, this benefit is mainly evident in the first year of follow-up. Indeed, DES-related events may extend over this time, due to late events (late ISR and/or very late stent thrombosis). Prevention of late failure of DES may become a specific therapeutic target.

Folic acid supplementation with and without vitamin B6 and revascularization risk: a meta-analysis of randomized controlled trials

BACKGROUND & AIMS

There is a growing amount of data and a continuing controversy over the effect of folic acid supplementation with and without vitamin B6 on revascularization risk.

METHODS

We conducted a meta-analysis based on up-to-date published relevant randomized trials to further examine this issue. Relative risk (RR) was used to measure the effect of folic acid supplementation on risk of revascularization using a random-effects model. Total revascularization was defined as any arterial revascularization. Restenosis was defined as stenosis of more than 50 percent of the luminal diameter.

RESULTS

Overall, folic acid supplementation had no significant effect on coronary revascularization (9 trials, n = 27,418, RR = 0.99; 95%CI:0.88-1.11, P = 0.88), coronary artery bypass grafting (CABG) (5 trials, n = 10,703, 0.90; 0.79-1.03, P = 0.11), percutaneous coronary intervention (PCI) (5 trials, n = 10,703, 1.05; 0.89-1.23, P = 0.59), coronary restenosis (3 trials, n = 926, 1.05; 0.89-1.23, P = 0.59) or total revascularization (7 trials, n = 29,314, 1.06; 95%CI: 0.99-1.13, P = 0.10). However, a greater beneficial effect was observed for coronary revascularization among those trials with a moderate dose of vitamin B6 (5-10 mg/d; RR: 0.47; 95%CI: 0.28-0.80, P = 0.005), but not in trials without vitamin B6 or with a high dose of vitamin B6. And a non-significant greater total revascularization risk was observed in trials with a higher folic acid dose (>2 mg/d, RR = 1.11; 95%CI: 0.98-1.25, P = 0.09; ≥5 mg/d, RR = 1.98; 95%CI: 0.93-4.20, P = 0.08).

CONCLUSIONS

Our analyses indicate that folic acid supplementation has no significant effect on coronary revascularization, CABG, PCI, coronary restenosis or total revascularization. However, a combination of folic acid and moderate vitamin B6 may be beneficial in reducing coronary revascularization risk.

Nanoparticle drug- and gene-eluting stents for the prevention and treatment of coronary restenosis

Percutaneous coronary intervention (PCI) has become the most common revascularization procedure for coronary artery disease. The use of stents has reduced the rate of restenosis by preventing elastic recoil and negative remodeling. However, in-stent restenosis remains one of the major drawbacks of this procedure. Drug-eluting stents (DESs) have proven to be effective in reducing the risk of late restenosis, but the use of currently marketed DESs presents safety concerns, including the non-specificity of therapeutics, incomplete endothelialization leading to late thrombosis, the need for long-term anti-platelet agents, and local hypersensitivity to polymer delivery matrices. In addition, the current DESs lack the capacity for adjustment of the drug dose and release kinetics appropriate to the disease status of the treated vessel. The development of efficacious therapeutic strategies to prevent and inhibit restenosis after PCI is critical for the treatment of coronary artery disease. The administration of drugs using biodegradable polymer nanoparticles as carriers has generated immense interest due to their excellent biocompatibility and ability to facilitate prolonged drug release. Despite the potential benefits of nanoparticles as smart drug delivery and diagnostic systems, much research is still required to evaluate potential toxicity issues related to the chemical properties of nanoparticle materials, as well as to their size and shape. This review describes the molecular mechanism of coronary restenosis, the use of DESs, and progress in nanoparticle drug- or gene-eluting stents for the prevention and treatment of coronary restenosis.

Panaxquin quefolium diolsaponins dose-dependently inhibits the proliferation of vascular smooth muscle cells by downregulating proto-oncogene expression

Objectives:

Panax quinquefolium saponins (PQS) potentially prevent atherosclerosis in vivo. The proliferation of vascular smooth muscle cells (VSMCs) plays an important role in coronary heart disease and restenosis after percutaneous coronary intervention. Here, we investigated the potential effect of Panax quinquefolium diolsaponins (PQDS), a subtype of PQS, on angiotensin II (AngII)-induced VSMC proliferation.

Materials and Methods:

Isolated rat VSMCs were identified by immunocytochemical analysis. Cell proliferation was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The cell cycle and proliferation index were analyzed using flow cytometry. The messenger ribonucleic acid (mRNA) expression of proto-oncogenes was evaluated using reverse transcription polymerase chain reaction.

Results:

Over 98% of cultured VSMCs were immunopositive for anti-α-smooth muscle actin. AngII promoted cell proliferation, whereas PQDS significantly suppressed VSMC growth in a dose-dependent manner. Moreover, PQDS suppressed AngII-induced proliferation of VSMCs by arresting the Gap 0/Gap 1 phase. Down-regulated mRNA expressions of proto-oncogenes occurred after PQDS application.

Conclusions:

Our study demonstrates that PQDS may reduce AngII-stimulated VSMC proliferation by suppressing the expression of proto-oncogenes. These results may provide insights for the development of novel traditional Chinese medicines to prevent atherosclerosis.

Nanoporous CREG-eluting stent attenuates in-stent neointimal formation in porcine coronary arteries

Background

The goal of this study was to evaluate the efficacy of a nanoporous CREG-eluting stent (CREGES) in inhibiting neointimal formation in a porcine coronary model.

Methods

In vitro proliferation assays were performed using isolated human endothelial and smooth muscle cells to investigate the cell-specific pharmacokinetic effects of CREG and sirolimus. We implanted CREGES, control sirolimus-eluting stents (SES) or bare metal stents (BMS) into pig coronary arteries. Histology and immunohistochemistry were performed to assess the efficacy of CREGES in inhibiting neointimal formation.

Results

CREG and sirolimus inhibited in vitro vascular smooth muscle cell proliferation to a similar degree. Interestingly, human endothelial cell proliferation was only significantly inhibited by sirolimus and was increased by CREG. CREGES attenuated neointimal formation after 4 weeks in porcine coronary model compared with BMS. No differences were found in the injury and inflammation scores among the groups. Scanning electron microscopy and CD31 staining by immunohistochemistry demonstrated an accelerated reendothelialization in the CREGES group compared with the SES or BMS control groups.

Conclusions

The current study suggests that CREGES reduces neointimal formation, promotes reendothelialization in porcine coronary stent model.

An Egr-1-specific DNAzyme regulates Egr-1 and proliferating cell nuclear antigen expression in rat vascular smooth muscle cells

The aim of the present study was to transfect rat aortic smooth muscle cells with an early growth response factor-1 (Egr-1)-specific DNAzyme (ED5), to observe its effect on Egr-1 and proliferating cell nuclear antigen (PCNA) expression and to elucidate the mechanism of ED5-mediated inhibition of vascular smooth muscle cell (VSMC) proliferation. VSMCs in primary culture obtained by tissue block adhesion were identified by morphological observation and α smooth muscle actin (α-SM-actin) immunocytochemistry. The cells were then transfected with ED5 or scrambled ED5 (ED5SCR). The three groups of cells used in the present study were the control group, ED5 group and ED5SCR group. The expression levels of Egr-1 and PCNA protein were detected following transfection by analyzing and calculating the integral optical density value in each group. Primary culture of VSMCs and transfection of ED5 and ED5SCR were successfully accomplished. Following stimulation with 10% fetal calf serum, the Egr-1 protein was expressed most strongly at 1 h and demonstrated a declining trend over time; the expression of PCNA protein began at 4 h, peaked at 24 h and then demonstrated a slightly declining trend over time. Compared with the control group and the ED5SCR group, ED5 inhibited the expression of Egr-1 and PCNA (P<0.05). ED5 was able to inhibit the expression of Egr-1 and PCNA proteins in VSMCs to a certain extent and VSMC proliferation in vitro. DNAzyme gene therapy may be useful as a new method for treating vascular proliferative diseases, including atherosclerosis and restenosis.

Impact of metabolic syndrome on re-stenosis development: role of drug-eluting stents

Metabolic syndrome (MetS) is defined as a cluster of numerous cardiovascular risk factors, which encompasses obesity, dyslipidaemia, insulin resistance and hypertension. Patients with MetS are more prone to developing cardiovascular events than other patients. To date, several approaches such as physical exercise, dietary control and invasive and non-invasive therapeutic interventions for dyslipidaemia, hypertension and insulin resistance have been used to manage MetS. However, there is a progressive elevation in the incidence of fatal and non-fatal cardiovascular events due to the increased prevalence of obesity and diabetes. Percutaneous coronary intervention has emerged over the last few years as an effective revascularisation strategy for those with coronary artery disease, in parallel with the development of effective anti-platelet medications and newer drug-eluting stents. In recent years, considerable research efforts have been undertaken to elucidate the pathophysiology of re-stenosis and develop strategies to prevent re-stenosis following percutaneous transluminal coronary angioplasty and stent implantation. Although the rate of stent re-stenosis and target-lesion revascularisation has been reduced, there is little information in the literature on the outcome of MetS in the pathophysiology of re-stenosis. In this review article, we summarise the recent development and progress on re-stenosis and the role of drug-eluting stents, particularly in MetS.

Improved cumulative survival in fistulas requiring surgical interventions to promote fistula maturation compared with endovascular interventions

Due to high nonmaturation rates, arteriovenous fistulas (AVF) frequently require intervention(s) to promote maturation. Endovascular or surgical interventions are often undertaken to salvage nonmaturing AVFs. The objective of this study was to compare the impact of surgical versus endovascular interventions to promote AVF maturation on cumulative AVF survival. We evaluated 89 patients with new AVF placement from a Veterans Affairs population over a 5-year period. Of these, 46 (52%) required intervention(s) to achieve successful maturation for dialysis: 31 patients had surgical revisions and 15 patients had endovascular repairs. We compared cumulative survival between AVFs requiring no intervention, surgical revision, and endovascular intervention to promote AVF maturation. Cumulative survival was longer in AVFs receiving surgical intervention compared with angioplasty to promote AVF maturation (p = 0.05). One-year cumulative survival was 86% vs. 83% vs. 40% for no intervention vs. surgery vs. angioplasty, respectively. In AVFs that required interventions to promote maturation, AVFs with surgical intervention had longer cumulative survival compared with those AVFs with endovascular intervention. AVFs with surgical intervention to promote maturation had similar 1-year cumulative survival to those AVFs that did not require intervention to promote maturation.

Effectiveness of triptolide-coated stent on decreasing inflammation and attenuation of intimal hyperplasia in a pig after coronary angioplasty

OBJECTIVE

The study is to test the efficacy of triptolide-coated stent on anti-inflammatory and inhibiting intimal hyperplasia in preventing restenosis.

METHODS

A total of 15 triptolide-coated stents (TCSs), 12 drug-eluting stents (DESs), and 12 bare metal stents (BMSs) were deployed in porcine coronary arteries. Coronary angiography, histopathologic and inflammatory markers levels were analyzed at 4 week after stenting.

RESULTS

At 4-week follow-up, quantitative coronary angiography (QCA) showed that minimum lumen diameter was greater, and percentage stenosis and late lumen loss in TCS group and DES group were less than that of BMS group. Compared to BMS group, injury and inflammation score in TCS group and DES group were decreased, neointimal area significantly reduced and lumen area enlarged in TCS, DES group as well.

CONCLUSION

Triptolide-coated stent showed the effect of preventing restenosis via inhibition of neointimal hyperplasia and anti-inflammation acts after coronary angioplasty.

Histopathologic evaluation of patent ductus arteriosus stents after hybrid stage I palliation

The aim of this study was to determine the histopathology of patent ductus arteriosus (PDA) in-stent stenosis after hybrid stage I palliation. The hybrid approach to palliation of hypoplastic left heart syndrome can be complicated by the development of in-stent stenosis of the PDA. This may obstruct retrograde aortic arch flow, decrease systemic circulation, and lead to interstage interventional procedures. Stented PDA samples removed from eight patients undergoing comprehensive stage II repair were examined by way of radiography and histochemistry (hematoxylin and eosin, Movat pentachrome, α-smooth muscle actin, and proliferating cell nuclear antigen). A retrospective chart review of the patients was also performed. PDA stents were in place in the PDA for a mean period of 169 ± 28 days in patients who had a mean age of 176 ± 30 days at the time of stent removal. Stent deployment caused chronic inflammation, caused fibrin deposition, and induced vascular smooth muscle-cell (VSMC) proliferation in the area immediately surrounding the stent struts. The neointimal region was composed largely of smooth muscle cells that appeared to be fully differentiated by the lack of PCNA staining. Neointimal thickening occurs in the PDA after stent placement for hybrid palliation of HLHS and is the result of inflammation, extracellular matrix deposition, and smooth muscle-cell proliferation in the peristrut region. This finding suggests that proliferating VSMCs in the peristrut region may provide the impetus for inward neointimal formation and therefore the manifestation of in-stent stenosis.

The evolving role of inflammatory biomarkers in risk assessment after stent implantation

The main adverse reactions to coronary stents are in-stent restenosis (ISR) and stent thrombosis. Along with procedural factors, individual susceptibility to these events plays an important role. In particular, inflammatory status, as assessed by C-reactive protein levels, predicts the risk of ISR after bare-metal stent implantation, although it does not predict the risk of stent thrombosis. Conversely, C-reactive protein levels fail to predict the risk of ISR after drug-eluting stent (DES) implantation, although they appear to predict the risk of stent thrombosis. Of note, DES have abated ISR rates occurring in the classical 1-year window, but new concern is emerging regarding late restenosis and thrombosis. The pathogenesis of these late events seems to be related to delayed healing and allergic reactions to polymers, a process in which eosinophils seem to play an important role by enhancing restenosis and thrombosis. The identification of high-risk individuals based on biomarker assessment may be important for the management of patients receiving stent implantation. In this report, we review the evolving role of inflammatory biomarkers in predicting the risk of ISR and stent thrombosis.

Eosinophil cationic protein and clinical outcome after bare metal stent implantation

OBJECTIVE

we assessed the association between baseline eosinophil cationic protein (ECP) levels, a sensitive marker of eosinophil activation, and clinical outcome in patients undergoing bare metal stent (BMS) implantation.

METHODS

basal ECP levels were measured in 110 patients (69±11 years, 88 men) undergoing BMS implantation. Major adverse cardiac events (MACEs), defined as cardiac death, non-fatal myocardial infarction, or clinically-driven target lesion revascularization, were registered at 24-month follow-up.

RESULTS

eighteen (16.4%) patients had MACEs and showed higher ECP levels compared with those without MACEs [20.1 (9.8-47.3) vs. 9.5 (5.0-27.2) g/L, p=0.02]. At follow-up, ECP level>11 g/L was the only significant predictor of MACEs (HR 3.5, 95% CI 1.1-10.4, p=0.03).

CONCLUSION

basal ECP levels are associated with MACEs after BMS implantation, suggesting that an allergic-mediated inflammation against the metal could explain some adverse reactions occurring after coronary stenting.

Decreased cumulative access survival in arteriovenous fistulas requiring interventions to promote maturation

BACKGROUND AND OBJECTIVES

New arteriovenous fistulas (AVF) are frequently unsuitable for hemodialysis because of AVF nonmaturation. Aggressive endovascular or surgical interventions are often undertaken to salvage nonmaturing AVFs. The effect of early interventions to promote AVF maturation on subsequent long-term AVF outcomes is unknown.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We evaluated 173 hemodialysis patients from two academic centers who received a new AVF. Of these, 96 (56%) required no further intervention, 54 (31%) required one intervention, and 23 (13%) required two or more interventions to achieve suitability for dialysis. We calculated AVF survival and frequency of postmaturation interventions in each group.

RESULTS

Cumulative AVF survival (access cannulation to permanent failure) in patients with two or more versus one versus zero interventions before maturation was 68% versus 78% versus 92% at 1 year, 57% versus 71% versus 85% at 2 years, and 42% versus 57% versus 75% at 3 years. Using Cox regression analysis with interventions before maturation, age, sex, race, diabetes, peripheral vascular disease, access site, and obesity in the model, intervention before maturation (two or more) was the only factor associated with cumulative AVF survival. The number of interventions required to maintain patency after maturation was 3.51 ± 2.20 versus 1.37 ± 0.31 versus 0.76 ± 0.10 per year in patients with two or more versus one versus zero interventions before maturation.

CONCLUSIONS

Compared with AVF that mature without interventions, AVF that require interventions have decreased cumulative survival and require more interventions to maintain their patency for hemodialysis.

Serum resistin levels and cardiovascular events in patients undergoing percutaneous coronary intervention

AIM

Resistin is an adipocytokine that may link inflammation and atherosclerosis.We studied the associations of resistin levels with cardiovascular events and restenosis.

METHODS

We measured pre-procedural serum resistin levels in 140 patients with coronary artery disease undergoing elective percutaneous coronary intervention (PCI), of whom 97 had a stent. Restenosis was defined as > 50% stenosis at follow-up angiography. Patients were followed for 3 years for major adverse cardiovascular events (MACE).

RESULTS

At 8±6 months after PCI, reangiography was performed in 94 (67%) patients, of whom 42 had restenosis. Between 42 patients with restenosis and 52 without restenosis, resistin (4.5±2.6 vs. 4.5±2.5 ng/mL) and Creactive protein (CRP) (median 0.70 vs. 0.70 mg/L) levels did not differ. During 3-year follow-up, MACE occurred in 24 patients (1 death, 21 unstable angina, 2 stroke). Compared with 116 patients without MACE, 24 with MACE had higher resistin (5.4±2.4 vs. 4.3±2.5 ng/mL) and CRP (1.30 vs. 0.60 mg/L) levels (p< 0.05). Patients with MACE more often had resistin >4.0 ng/mL than without MACE (75% vs. 35%, p< 0.001). Resistin correlated with CRP levels (r= 0.31). To clarify the association between MACE and resistin, patients were divided into 2 groups by resistin levels. Kaplan-Meier analysis showed a lower event-free survival rate in patients with resistin > 4.0 ng/mL than without it (p< 0.001). On multivariate analysis, resistin, but not CRP, was an independent predictor of MACE. The hazard ratio for MACE was 3.6 (95%CI=1.4-9.2) for resistin > 4.0 ng/mL.

CONCLUSION

Serum resistin levels were found to be associated with further cardiovascular events in patients undergoing PCI.

The effects of freezing versus supercooling on vascular cells: implications for balloon cryoplasty

PURPOSE

To investigate the effects of supercooling, a phase whereby cells are below 0 degrees C but still in a liquid state, and freezing, the phase when cells become solid, of vascular cells in culture.

MATERIALS AND METHODS

Bovine aortic endothelial cells and smooth muscle cells were supercooled to -10 degrees C with or without freezing for 3, 30, or 60 seconds and then rewarmed to 37 degrees C for 24 hours. Viability was assessed by means of trypan blue exclusion, and apoptosis was assessed with the TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay.

RESULTS

Viability of smooth muscle cells decreased 49% after freezing versus supercooling (P< .05). Endothelial cells maintained greater viability rates. A 19.5% smooth muscle cell apoptotic rate was observed after freezing, whereas smooth muscle cell supercooling yielded rates of only 11% (P< .05). A 4.17% endothelial cell apoptotic rate was observed after freezing, whereas supercooled endothelial cells yielded a 1.76% rate (P< .05).

CONCLUSIONS

Freezing results in decreased viability and increased apoptosis compared to supercooling in both cell lines. Smooth muscle cells appear more susceptible to freezing. The biologic effects of freezing on vascular cells may elucidate the mechanisms behind the enhanced patency after cryoplasty of atherosclerotic lesions.

Preclinical Models of Restenosis and Their Application in the Evaluation of Drug-Eluting Stent Systems

Coronary arterial disease (CAD) is the leading cause of death in the United States, the European Union, and Canada. Percutaneous coronary intervention (PCI) has revolutionized the treatment of CAD, and it is the advent of drug-eluting stent (DES) systems that has effectively allayed much of the challenge of restenosis that has plagued the success of PCI through its 30-year history. However, DES systems have not been a panacea: There yet remain the challenges associated with interventions involving bare metallic stents as well as newly arisen concerns related to the application of DES systems. To effectively address these novel and ongoing issues, animal models are relied on both to project the safety and efficacy of endovascular devices and to provide insight into the pathophysiology underlying the vascular response to injury and mechanisms of restenosis. In this review, preclinical models of restenosis are presented, and their application and limitation in the evaluation of device-based interventional technologies for the treatment of CAD are discussed.

Variation in the human soluble epoxide hydrolase gene and risk of restenosis after percutaneous coronary intervention

Background

Restenosis represents the major limiting factor for the long-term efficacy of percutaneous coronary intervention (PCI). Several genetic factors involved in the regulation of the vascular system have been described to play a role in the pathogenesis of restenosis. We investigated whether the EPHX2 K55R polymorphism, previously linked to significantly higher risk for coronary heart disease (CHD), was associated with the occurrence of restenosis after PCI. The association with incident CHD should have been confirmed and a potential correlation of the EPHX2 K55R variant to an increased risk of hypertension was analysed.

Methods

An overall cohort of 706 patients was studied: This cohort comprised of 435 CHD patients who had undergone successful PCI. Follow-up coronary angiography in all patients was performed 6 months after intervention. Another 271 patients in whom CHD had been excluded by coronary angiography served as controls. From each patient EDTA-blood was drawn at the baseline ward round. Genomic DNA was extracted from these samples and genotyping was performed by real-time PCR and subsequent melting curve analysis.

Results

In CHD patients 6 month follow-up coronary angiography revealed a restenosis rate of 29.4%, classified as late lumen loss as well as lumen re-narrowing ≥ 50%.

Statistical analysis showed an equal genotype distribution in restenosis patients and non-restenosis patients (A/A 82.0% and A/G + G/G 18.0% versus A/A 82.1% and A/G + G/G 17.9%). Moreover, neither a significant difference in the genotype distribution of CHD patients and controls nor an association with increased risk of hypertension was found.

Conclusion

The results of the present study indicate that the EPHX2 K55R polymorphism is not associated with restenosis after PCI, with incidence of CHD, or with an increased risk of hypertension and therefore, can not serve as a predictor for risk of CHD or restenosis after PCI.

Current issues in coronary stent technology

Coronary artery stents have become the medical device of choice for the treatment of coronary artery disease. Since their introduction in 1987, significant advances in stent technology have taken place. A major objective of these developments was the reduction of in-stent restenosis, the formation of neointimal tissue inside the stent triggered by vessel injury and the inflammatory response, which results in renarrowing of the coronary artery. Improvements in strut configuration, thickness, and materials have enhanced deliverability and reduced vessel damage. Currently available drug-eluting stents release drugs that reduce neointimal formation through the arrest of cell proliferation. Drug-eluting stents have significantly reduced rates of in-stent restenosis. However, concerns have been raised with respect to their long-term safety, particularly in relation to the occurrence of late thrombosis. The post-procedural monitoring of stent-related complications is also of interest, including the relative suitability of invasive techniques such as angiography and intravascular ultrasound, and non-invasive techniques such as computed tomography and magnetic resonance imaging scanning. This paper reviews the current issues in stent technology.

Optical coherence tomography patterns of stent restenosis

BACKGROUND

Stent restenosis is an infrequent but poorly understood clinical problem in the drug-eluting stent era. The aim of the study was to evaluate the morphologic characteristics of stent restenosis by optical coherence tomography (OCT).

METHODS

Patients (n = 24, 25 vessels) presenting with angiographically documented stent restenosis were included. Quantitative OCT analysis consisted of lumen and stent area measurement and calculation of restenotic tissue area and burden. Qualitative restenotic tissue analysis included assessment of tissue structure, backscattering and symmetry, visible microvessels, lumen shape, and presence of intraluminal material.

RESULTS

By angiography, restenosis was classified as diffuse, focal, and at the margins in 9, 11, and 5 vessels, respectively. By OCT, restenotic tissue structure was layered in 52%, homogeneous in 28%, and heterogeneous in 20%. The predominant backscatter was high in 72%. Microvessels were visible in 12%. Lumen shape was irregular in 28% and there was intraluminal material in 20%. The mean restenotic tissue symmetry ratio was 0.58 +/- 0.19. Heterogeneous and low scattering restenotic tissue was more frequent in focal (45.5% and 54.5%, respectively) than in diffuse (0 and 11.1%) and margin restenosis (0 and 0%) (P = .005 for heterogeneous, P = .03 for low scattering). Restenosis patients with unstable angina symptoms presented more frequently irregular lumen shape (60 vs 6.7%, P = .007). Stents implanted </=12 months ago had more frequently restenotic tissue with layered appearance (84.6% vs 16.7%, P = .003).

CONCLUSIONS

We demonstrate the ability of OCT to identify differential patterns of restenotic tissue after stenting. This information could help in understanding the mechanism of stent restenosis.