Histologic evidence of foreign body granulation tissue and de novo lesions in patients with coronary stent restenosis

Intrastent Restenosis: A Comprehensive Review

The primary objective of this paper is to delineate and elucidate the contemporary advancements, developments, and prevailing trajectories concerning intrastent restenosis (ISR). We aim to provide a thorough overview of the most recent developments in this area, covering various aspects such as pathophysiological insights, therapeutic approaches, and new strategies for tackling the complex challenges of ISR in modern clinical settings. The authors have undertaken a study to address a relatively new medical challenge, recognizing its significant impact on the morbidity and mortality of individuals with cardiovascular diseases. This effort is driven by the need to fully understand, analyze, and possibly improve the outcomes of this emerging medical issue within the cardiovascular disease field. We acknowledge its considerable clinical implications and the necessity for innovative methods to mitigate its effects on patient outcomes. Therefore, our emphasis was directed towards elucidating the principal facets of the condition's prevalence, expounding upon the foundational mechanisms underscoring conspicuous restenosis, and delineating the risk factors relevant in shaping the contemporary landscape of diagnostic and therapeutic modalities. This thorough examination aims to provide a comprehensive understanding of the various dimensions of the condition, including epidemiological data, pathophysiological complexities, and clinical considerations critical for evaluating and enhancing current diagnostic and treatment approaches.

Association Between Three Atopic Triad and Retinal Vein Occlusion Risk: A Nationwide Population-Based Study

PURPOSE

To evaluate the association between three allergic diseases (allergic dermatitis, allergic rhinitis, and asthma) and the development of retinal vein occlusion (RVO), a major retinal disease that causes visual impairment.

METHOD

This study used data obtained from the Korean National Health Insurance Claims database between 2009 and 2018. The association between the three atopic triads (allergic dermatitis, allergic rhinitis, and asthma) and the occurrence of sight-threatening RVO, as determined by diagnostic and treatment codes, were analyzed. Multivariate adjusted Cox regression analysis was used to determine the hazard ratios (HRs) and 95% confidence intervals for RVO development in the presence of allergic disease.

RESULTS

In this population-based study, 2,160,195 (54.6%) individuals were male, 1,794,968 (45.4%) were female, and 620,938 (15.7%) were diagnosed with allergic diseases. Patients with either asthma or allergic rhinitis had a greater risk of RVO (adjusted hazard ratio (aHR) = 1.101, 95% confidence interval [CI] = 1.029-1.178 for asthma; aHR = 1.181, 95% CI = 1.147-1.215 for allergic rhinitis) compared to those without asthma or allergic rhinitis; however, patients with atopic dermatitis did not show a significant association with RVO (aHR = 1.071, 95% CI = 0.889-1.290), after adjusting for other risk factors.

CONCLUSION

Our study revealed that allergic rhinitis, asthma, and coexisting multiple allergic conditions were associated with an increased risk of RVO. Thus, it may be advisable to suggest an ophthalmological examination for patients with allergies due to the increased possibility of the occurrence of retinal vascular disease.

Restenosis after Coronary Stent Implantation: Cellular Mechanisms and Potential of Endothelial Progenitor Cells (A Short Guide for the Interventional Cardiologist)

Coronary stents are among the most common therapies worldwide. Despite significant improvements in the biocompatibility of these devices throughout the last decades, they are prone, in as many as 10–20% of cases, to short- or long-term failure. In-stent restenosis is a multifactorial process with a complex and incompletely understood pathophysiology in which inflammatory reactions are of central importance. This review provides a short overview for the clinician on the cellular types responsible for restenosis with a focus on the role of endothelial progenitor cells. The mechanisms of restenosis are described, along with the cell-based attempts made to prevent it. While the focus of this review is principally clinical, experimental evidence provides some insight into the potential implications for prevention and therapy of coronary stent restenosis.

Assessment of structural, biological and drug release properties of electro-sprayed poly lactic acid-dexamethasone coating for biomedical applications

The efficacy of an implant is highly depends on its coating characteristics mainly determined by polymer properties and coating technique. Electro-spraying is an inexpensive and versatile coating technique with various advantages for biomedical application. In this study, the efficacy of electro-sprayed (ES) poly lactic acid (PLA)-dexamethasone (DEX) coatings for medical implants was evaluated and compared with spin-coated samples as control. Structural properties of coatings were investigated using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Confocal and scanning electron microscopy (SEM), contact angle measurement and nanoindentation tests were used to study surface properties. Coating degradation rate and drug release profile were studied for 40 days. Cell viability experiments were also performed on human endothelial (HUVEC) and smooth muscle cells (HUASMC) using MTT assay and SEM. XRD and DSC analysis showed electro-spraying significantly reduce PLA and DEX crystallinity. Surface studies showed ES coatings has significantly higher hydrophobicity and roughness with microbead-nanofiber morphology vs. micro-nanoporous structure of spin-coated samples. Initial burst release of DEX was 22% and 10% after 6 h and total release was 71% and 46% after 40 days for ES and spin-coated samples, respectively. HUVEC viability of ES samples was higher than spin-coated ones after 1 and 4 days. However, dexamethasone release profile reduced HUASMC proliferation in ES PLA-DEX samples in comparison to spin-coated after 1 and 3 days. In conclusion, in vitro results showed potential of ES PLA-DEX as a biocompatible and efficient anti-inflammatory coating with suitable drug release profile for future applications such as coronary drug eluting stents.

Targeting Smad-Mediated TGFß Pathway in Coronary Artery Bypass Graft

Revascularization surgeries such as coronary artery bypass grafting (CABG) are sometimes necessary to manage coronary heart disease (CHD). However, more than half of these surgeries fail within 10 years due to the development of intimal hyperplasia (IH) among others. The cytokine transforming growth factor-beta (TGFß) and its signaling components have been found to be upregulated in diseased or injured vessels, and to promote IH after grafting. Interventions that globally inhibit TGFß in CABG have yielded contrasting outcomes in in vitro and in vivo studies including clinical trials. With advances in molecular biology, it becomes clear that TGFß exhibits both protective and damaging roles, and only specific components such as some Smad-dependent TGFß signaling mediate vascular IH. The activin receptor-like kinase (ALK)-mediated Smad-dependent TGFß signaling pathways have been found to be activated in human vascular smooth muscle cells (VSMCs) following injury and in hyperplastic preimplantation vein grafts. It appears that focused targeting of TGFß pathway constitutes a promising therapeutic target to improve the outcome of CABG. This study dissects the role of TGFß pathway in CABG failure, with particular emphasis on the therapeutic potentials of specific targeting of Smad-dependent and ALK-mediated signaling.

Carbon-Coated Stent and the Role of the Kallikrein-Kinin System in Peripheral Angioplasty

OBJECTIVE

The purpose of this study was to investigate the clinical evolution of patients treated with carbon-coated stent, as well as its patency and the inflammatory response triggered by this process through the quantification of serum elements of the kallikrein-kinin system (KKS).

METHODS

This was a single-center prospective study with 27 patients with peripheral artery disease (PAD) who required percutaneous transluminal angioplasty and stenting of the iliacofemoropopliteal segment using carbon-coated stent grafts (carbostents). The blood concentrations of the total and kininogen fractions were evaluated using immunoenzymatic methods. Plasma kallikrein levels were assessed by the colorimetric method and tissue kallikrein levels were evaluated by the spectrophotometric method. The activity of kininase II was measured by -fluorometric analysis.

RESULTS

Of the 27 patients who completed the 6 months of the study (11 iliac territory, 16 femoropopliteal territory), only one experienced restenosis (3.7%) (femoropopliteal segment) and no patient had occlusion (96.3% of patency). In 1 year, four patients were lost to follow-up and all 23 patients evaluated maintained stent patency, except for the patient who had restenosis throughout the first 6 months. We report complete (100%) member salvage in 12 months of follow-up. The activity levels of high- and low-molecular-weight kininogens decreased significantly over time (before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.001, and before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.001; 24 h vs. 6 months, p < 0.001, respectively). Patients also had significantly lower levels of plasma and tissue kallikrein (before vs. 24 h, p < 0.001; before vs. 6 months, p < 0.001, and before vs. 24 h, p < 0.01; before vs. 6 months, p < 0.05, respectively). There was a significant increase in the enzymatic activity of kininase II at 24 h and after 6 months compared to the pre-treatment control (p < 0.001).

CONCLUSION

Our early experience shows that the use of carbon-coated stents in PAD appears to be safe, with low rates of early restenosis (3.7% in the first 6 months and 5% in the 12 months of follow-up). We concluded that KKS was involved in the inflammatory response caused by the placement of carbon-coated stents.

Gene Delivery from Stents for Prevention of In-Stent Restenosis

The increasing sophistication of vascular stent design, especially devices that combine mechanical support with local drug delivery to the vascular wall, has resulted in major progress in the management of coronary and peripheral artery disease. This progress is reflected in expanded anatomical and clinical indications for stent angioplasty, with complementary reduction in bypass surgery rates and decreased need for target-lesion revascularisation. Nevertheless, even with second-generation drug-eluting stents (DES), the most common cause of stent failure, in-stent restenosis, while <10%, generates high numbers of cases due to the large scale of stent use (there are >1 million stent angioplasty procedures yearly in the USA alone). Gene-eluting stents (GES), the next generation of stent devices now in the preclinical phase of development, have evolved over the past two decades around the concept of localised vessel wall delivery of gene vectors attached to the stent struts. GES potentially provide several important advantages over DES, such as prolonged or even permanent anti-restenotic effect, capacity to deliver dissimilar impact on smooth muscle cells and endothelium, and fine-tuning of transgene expression and pharmacological effect with systemically administered therapeutics. Furthermore, GES can be used for treating non-occlusive lesions with the aim of slowing the underlying atherosclerotic process in the vessel wall. GES research at this time is concerned with achieving effective and safe transgene overexpression in the stented arteries, optimal vector choice, and proper techniques for vector immobilisation on the stent struts.

Immuno-Informed 3D Silk Biomaterials for Tailoring Biological Responses

Macrophages, the key players in immunoregulation, are actively involved in tissue remodelling and vascularization. Recent advances in tissue engineering and regenerative medicine illustrate the importance of "immuno-informed" biomaterials to regulate the microenvironment of biomedical implants. In the current study, silk-based 3D hydrogels were utilized to regulate cytokine delivery for macrophage, a type of immune cell, differentiation and polarization. Three different hydrogel variants, silk-poly(ethylene glycol) (PEG) (SP), silk-horseradish peroxidase (HRP) (SH) and silk-sonicated (SS) hydrogels were studied. Hydrogels were loaded with the M1 and M2 polarizing cytokines interferon-γ (IFN-γ) and interleukin-4 (IL-4), respectively. Functional cytokine release and macrophage polarization studies were conducted using three cytokine exposure approaches: only cytokine encapsulation (macrophage in culture well), only macrophage encapsulation (cytokine in culture media) and cytokine with macrophage encapsulation. The extent of macrophage polarization by cytokine-eluting and macrophage-encapsulating hydrogels was investigated using gene expression analysis for C-C chemokine receptor 7 (CCR7), Interleukin-1 beta (IL-1β), cluster of differentiation 206 (CD206) and cluster of differentiation 209 (CD209). The released cytokines polarized macrophages from an M0 phenotype to an M1/M2 phenotype. Also, lineage committed M1/M2 macrophages could be "switched" to their M2/M1 counterparts (M1-to-M2 or M2-to-M1 transition) exhibiting their well-established plasticity. When macrophages were encapsulated in hydrogels, polarization could be induced to the lineage committed M1 or M2 phenotypes either in polarizing media or when coencapsulated with cytokines. Through this study, silk hydrogels demonstrated utility as a novel system for focal delivery of cytokines and macrophages as "immuno-informed" 3D silk-biomaterials.

Techniques in Vascular and Interventional Radiology Drug Delivery Technologies in the Superficial Femoral Artery

Peripheral arterial disease (PAD) affects over 8 million people in the United States alone. Although great strides have been made in reducing the burden of cardiovascular disease the prevalence of PAD is expected to rise with the age of global population. PAD characterized by narrowing of arterial blood can be asymptomatic or cause limb threatening claudication. It has been classically treated with bypass, but these techniques have been supplanted by endovascular therapy. Plain old balloon angioplasty has been successful in helping revascularize lesions, but its effect has not been durable because of restenosis. This prompted the creation of several technologies aimed at reducing restenosis. These advances slowly improved outcomes and the durability of endovascular management. Among the main tools used in current endovascular practice are drug-delivery devices aimed at inhibiting the inflammatory and proliferative pathways that lead to restenosis. This article examines the current drug-delivery technologies used in the superficial femoral artery.

Controlled release of cytokines using silk-biomaterials for macrophage polarization

Polarization of macrophages into an inflammatory (M1) or anti-inflammatory (M2) phenotype is important for clearing pathogens and wound repair, however chronic activation of either type of macrophage has been implicated in several diseases. Methods to locally control the polarization of macrophages is of great interest for biomedical implants and tissue engineering. To that end, silk protein was used to form biopolymer films that release either IFN-γ or IL-4 to control the polarization of macrophages. Modulation of the solubility of the silk films through regulation of β-sheet (crystalline) content enabled a short-term release (4-8 h) of either cytokine, with smaller amounts released out to 24 h. Altering the solubility of the films was accomplished by varying the time that the films were exposed to water vapor. The released IFN-γ or IL-4 induced polarization of THP-1 derived macrophages into the M1 or M2 phenotypes, respectively. The silk biomaterials were able to release enough IFN-γ or IL-4 to repolarize the macrophage from M1 to M2 and vice versa, demonstrating the well-established plasticity of macrophages. High β-sheet content films that are not soluble and do not release the trapped cytokines were also able to polarize macrophages that adhered to the surface through degradation of the silk protein. Chemically conjugating IFN-γ to silk films through disulfide bonds allowed for longer-term release to 10 days. The release of covalently attached IFN-γ from the films was also able to polarize M1 macrophages in vitro. Thus, the strategy described here offers new approaches to utilizing biomaterials for directing the polarization of macrophages.

The relationship between eosinophilia and slow coronary flow

Aim

The pathophysiology of slow coronary flow (SCF) involves atherosclerosis, small vessel dysfunction, platelet function disorders, and inflammation. It has been known that eosinophils also play a significant role in inflammation, vasoconstriction, thrombosis, and endothelial dysfunction. We propose to evaluate the relationship between eosinophilia and SCF.

Methods

All patients who underwent coronary angiography between January 2011 and December 2013 were screened retrospectively. Of 6,832 patients, 102 patients with SCF (66 males, mean age 52.2±11.7 years) and 77 control subjects with normal coronary angiography (50 males, mean age 50.7±8.1 years) were detected. Baseline characteristics, hematological test results, and biochemical test results were obtained from the hospital database.

Results

Baseline characteristics of the study groups were comparable between groups. There was no significant difference between groups regarding leukocyte count, paletelet count, and mean platelet volume. However, patients with SCF had a higher eosinophil count than the controls (0.24±0.17×10³/μL vs 0.16±0.15×10³/μL, P=0.002). In addition, eosinophil count was found to be correlated with thrombolysis in myocardial infarction (TIMI) frame count in the SCF group (r=0.3, P<0.01). There was no significant correlation between eosinophil count and the number of coronary arteries showing slow flow.

Conclusion

Patients with SCF have higher blood eosinophil count, and this may play an important role in the pathogenesis of SCF. Elevated baseline eosinophil count may indicate the presence of SCF.

The relationship between eosinophil and cardiac syndrome X

AIM

The pathophysiology of cardiac syndrome X (CSX) has not been clearly identified, although multiple abnormalities including microvascular spasm, endothelial dysfunction, and atherothrombosis have been reported. It is known that eosinophils play an important role in vasoconstruction and thrombosis. We aimed to compare the eosinophil counts in patients with CSX versus controls.

MATERIALS AND METHODS

This study included 50 patients with CSX (20 male, mean age 50.42 ± 9.6 years) and 30 control persons (10 male, mean age 49.16.11 ± 9.2 years). These participants underwent concurrent routine biochemical tests, and their eosinophil counts were obtained on whole blood count. These parameters were compared between groups.

RESULTS

Baseline characteristics of the study groups were comparable. Patients with CSX had a higher eosinophil count and mean platelet volume (MPV) value than the controls (339.4 ± 188 vs 132.7 ± 75 and 8.8 ± 0.2 vs 7.2 ± 0.1 fL; P < .001, respectively).

CONCLUSION

As a result, our study revealed a relationship between eosinophil count and MPV in patients with CSX.

Modulation of NO and ROS production by AdiNOS transduced vascular cells through supplementation with L-Arg and BH4: implications for gene therapy of restenosis

OBJECTIVE

Gene therapy with viral vectors encoding for NOS enzymes has been recognized as a potential therapeutic approach for the prevention of restenosis. Optimal activity of iNOS is dependent on the intracellular availability of L-Arg and BH4 via prevention of NOS decoupling and subsequent ROS formation. Herein, we investigated the effects of separate and combined L-Arg and BH4 supplementation on the production of NO and ROS in cultured rat arterial smooth muscle and endothelial cells transduced with AdiNOS, and their impact on the antirestenotic effectiveness of AdiNOS delivery to balloon-injured rat carotid arteries.

METHODS AND RESULTS

Supplementation of AdiNOS transduced endothelial and vascular smooth muscle cells with L-Arg (3.0 mM), BH4 (10 μM) and especially their combination resulted in a significant increase in NO production as measured by nitrite formation in media. Formation of ROS was dose-dependently increased following transduction with increasing MOIs of AdiNOS. Exposure of RASMC to AdiNOS tethered to meshes via a hydrolyzable cross-linker, modeling viral delivery from stents, resulted in increased ROS production, which was decreased by supplementation with BH4 but not L-Arg or L-Arg/BH4. Enhanced cell death, caused by AdiNOS transduction, was also preventable with BH4 supplementation. In the rat carotid model of balloon injury, intraluminal delivery of AdiNOS in BH4-, L-Arg-, and especially in BH4 and L-Arg supplemented animals was found to significantly enhance the antirestenotic effects of AdiNOS-mediated gene therapy.

CONCLUSIONS

Fine-tuning of iNOS function by L-Arg and BH4 supplementation in the transduced vasculature augments the therapeutic potential of gene therapy with iNOS for the prevention of restenosis.

The ALK-1/Smad1 pathway in cardiovascular physiopathology. A new target for therapy?

Activin receptor-like kinase-1 or ALK-1 is a type I cell surface receptor for the transforming growth factor-β (TGF-β) family of proteins. The role of ALK-1 in endothelial cells biology and in angiogenesis has been thoroughly studied by many authors. However, it has been recently suggested a possible role of ALK-1 in cardiovascular homeostasis. ALK-1 is not only expressed in endothelial cells but also in smooth muscle cells, myofibroblast, hepatic stellate cells, chondrocytes, monocytes, myoblasts, macrophages or fibroblasts, but its role in these cells have not been deeply analyzed. Due to the function of ALK-1 in these cells, this receptor plays a role in several cardiovascular diseases. Animals with ALK-1 haploinsufficiency and patients with mutations in Acvrl1 (the gene that codifies for ALK-1) develop type-2 Hereditary Hemorrhagic Telangiectasia. Moreover, ALK-1 heterozygous mice develop pulmonary hypertension. Higher levels of ALK-1 have been observed in atherosclerotic plaques, suggesting a possible protector role of this receptor. ALK-1 deficiency is also related to the development of arteriovenous malformations (AVMs). Besides, due to the ability of ALK-1 to regulate cell proliferation and migration, and to modulate extracellular matrix (ECM) protein expression in several cell types, ALK-1 has been now demonstrated to play an important role in cardiovascular remodeling. In this review, we would like to offer a complete vision of the role of ALK-1 in many process related to cardiovascular homeostasis, and the involvement of this protein in the development of cardiovascular diseases, suggesting the possibility of using the ALK-1/smad-1 pathway as a powerful therapeutic target.

The effects of eosinophil on the left atrial thrombus in patients with atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common cardiac rhythm disorder. Atrial fibrillation causes a 5-fold increased risk for thromboembolic stroke. It is known that eosinophils play an important role in thrombosis. We aimed to compare the number of eosinophil counts of the patients with and without thrombi in the left atrium (LA) or in the left atrial appendage (LAA) and to ascertain the association of eosinophil counts with the presence of thrombi.

METHOD

The study included 89 patients diagnosed with persistent AF who underwent transesophageal echocardiography and designated to undergo cardioversion. The patients were divided into 2 groups: group 1 consisted of 40 patients (18 male; average age 63.27 ± 1.4) who had thrombus formation in the LA or LAA, and group 2 consisted of 49 patients (23 male; average age 66.53 ± 1.56) who did not have any thrombus in the LA or LAA. These patients underwent concurrent routine biochemical tests and eosinophil count on whole blood count was also performed.

RESULTS

Baseline characteristics of the study groups were comparable. Group 1 patients had higher eosinophil and mean platelet volume values than group 2 (233.0 ± 30.7 vs 118.9 ± 11.8 and 9.77 ± 0.20 vs 8.27 ± 0.12 fL, P < .001, respectively). In group 1, the patients' LA diameter is higher than that in group II.

CONCLUSION

As a result, our study revealed a relationship between eosinophil count and LA thrombus in patients with nonvalvular AF.

Endovascular Gene Delivery from a Stent Platform: Gene- Eluting Stents

A synergistic impact of research in the fields of post-angioplasty restenosis, drug-eluting stents and vascular gene therapy over the past 15 years has shaped the concept of gene-eluting stents. Gene-eluting stents hold promise of overcoming some biological and technical problems inherent to drug-eluting stent technology. As the field of gene-eluting stents matures it becomes evident that all three main design modules of a gene-eluting stent: a therapeutic transgene, a vector and a delivery system are equally important for accomplishing sustained inhibition of neointimal formation in arteries treated with gene delivery stents. This review summarizes prior work on stent-based gene delivery and discusses the main optimization strategies required to move the field of gene-eluting stents to clinical translation.

Renal artery stenosis: prevalence of, risk factors for, and management of in-stent stenosis

Atherosclerotic renal artery stenosis is common and is associated with hypertension and chronic kidney disease. More frequent use of percutaneous renal artery stent placement for the treatment of renal artery stenosis during the past 2 decades has increased the number of patients with implanted stents. In-stent stenosis is a serious problem, occurring more frequently than earlier reports suggest and potentially resulting in late complications. Currently, there are no guidelines covering the approach to restenosis after renal artery stent placement. This article reviews data on the prevalence of and risk factors for the development of in-stent stenosis and the clinical manifestations, evaluation, and treatment of in-stent stenosis and suggests a strategy for the management of patients after percutaneous renal artery stent placement.

Nanoparticle-mediated local delivery of an antisense TGF-β1 construct inhibits intimal hyperplasia in autogenous vein grafts in rats

Background

Intimal hyperplasia is one of the most important causes of vascular graft failure. Numerous studies have correlated transforming growth factor-β1 (TGF-β1) with extracellular matrix (ECM) deposition, a hallmark of intimal thickening.

Principal Findings

In the present study, we performed immunohistochemistry, RT-PCR, and Western blot to examine the dynamic expression of TGF-β1, TGF-β1 receptor type I (TGF-β RI), matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) during intimal hyperplasia in grafted veins of a rat model generated by grafting a portion of the right internal jugular vein to the ipisiliary caroid artery. Additionally, we determined whether nanoparticle-mediated delivery of a TGF-β1 antisense-expressing construct prevented TGF-β1 expression and intimal hyperplasia in grafted veins. In grafted veins, the expression of TGF-β1 significantly increased on day 3 after transplantation, peaked on day 7, slightly decreased on day 14, and returned to baseline levels on day 28. The positive expression of TGF-β RI in grafted veins remarkably increased on day 7, peaked on day 14, and decreased thereafter. MMP-1 expression decreased significantly, while TIMP-1 expression increased, significantly on days 14 and 28. Nanoparticle-mediated delivery of a TGF-β1 antisense-expressing construct down-regulated TGF-β1 expression and inhibited intimal hyperplasia in grafted veins.

Conclusions

Our findings provide further evidence that TGF-β1 plays an integral role in the development of intimal hyperplasia after vascular injury. Nanoparticle-mediated delivery of a TGF-β1 antisense-expressing construct is a feasible strategy to target TGF-β1-induced intimal thickening.

TGF-β and Smad3 modulate PI3K/Akt signaling pathway in vascular smooth muscle cells

Transforming growth factor-β (TGF-β) is upregulated at the time of arterial injury; however, the mechanism through which TGF-β enhances the development of intimal hyperplasia is not clear. Recent studies from our laboratory suggest that in the presence of elevated levels of Smad3, TGF-β stimulates smooth muscle cell (SMC) proliferation. This is a novel phenomenon in that TGF-β has traditionally been known as a potent inhibitor of cellular proliferation. In these studies we explore the signaling pathways through which TGF-β mediates its proliferative effect in vascular SMCs. We found that TGF-β phosphorylates and activates Akt in a time-dependent manner, and this effect is significantly enhanced by overexpression of Smad3. Furthermore, both chemical and molecular inhibition of Smad3 can reverse the effect of TGF-β on Akt. Although we found numerous signaling pathways that might function as intermediates between Smad3 and Akt, p38 appeared the most promising. Overexpression of Smad3 enhanced p38 phosphorylation and inhibition of p38 with a chemical inhibitor or a small interfering RNA blocked TGF-β-induced Akt phosphorylation. Moreover, TGF-β/Smad3 enhancement of SMC proliferation was blocked by inhibition of p38. Phosphorylation of Akt by TGF-β/Smad3 was not dependent on gene expression or protein synthesis, and immunoprecipitation studies revealed a physical association among p38, Akt, and Smad3 suggesting that activation requires a direct protein-protein interaction. Our findings were confirmed in vivo where overexpression of Smad3 in a rat carotid injury model led to enhancement of p-p38, p-Akt, as well as SMC proliferation. Furthermore, inhibition of p38 in vivo led to decreased Akt phosphorylation and SMC proliferation. In summary, our studies reveal a novel pathway whereby TGF-β/Smad3 stimulates SMC proliferation through p38 and Akt. These findings provide a potential mechanism for the substantial effect of TGF-β on intimal hyperplasia and suggest new targets for chemical or molecular prevention of vascular restenosis.

TGF-β and restenosis revisited: a Smad link

Despite novel surgical therapies for the treatment of atherosclerosis, restenosis continues to be a significant impediment to the long-term success of vascular interventions. Transforming growth factor-beta (TGF-β), a family of cytokines found to be up-regulated at sites of arterial injury, has long been implicated in restenosis; a role that has largely been attributed to TGF-β-mediated vascular fibrosis. However, emerging data indicate that the role of TGF-β in intimal thickening and arterial remodeling, the critical components of restenosis, is complex and multidirectional. Recent advancements have clarified the basic signaling pathway of TGF-β, making evident the need to redefine the precise role of this family of cytokines and its primary signaling pathway, Smad, in restenosis. Unraveling TGF-β signaling in intimal thickening and arterial remodeling will pave the way for a clearer understanding of restenosis and the development of innovative pharmacological therapies.

Coronary bare metal stent implantation in homozygous LDL receptor deficient swine induces a neointimal formation pattern similar to humans

INTRODUCTION

To date, most of all new developments in stent technologies are tested in normal animals. Although invaluable in the evaluation of device safety, the juvenile domestic swine (DS) do not follow the biological healing response occurring in humans following coronary stent implantation. By using a novel swine breed afflicted with familial hypercholesterolemia (FHS), we aimed to analyse the vascular response occurring following bare metal stent (BMS) implantation by comparing in vivo endovascular imaging and histological data.

METHODS

A total of 26 swine were included in this study (12 FHS and 14 DS). Sixty eight BMS (FHS=28 versus DS=40) were implanted using a 10% overstretch ratio. Imaging evaluation (IVUS and OCT) was conducted in all animals at 30 (n=14) or 90 (n=12) days following stent implantation. After imaging, the stented coronary segments were harvested for histological evaluation.

RESULTS

At 30 days, the degree of neointimal formation analysed by OCT (%AS=DS 21.9 ± 10% versus FHS 25.4 ± 12%; p=0.18) and histology (DS 24.6 ± 10% versus FHS 23.58 ± 10%; p=0.8) was similar between both animal groups. At 90 days, the degree of neointimal formation in the DS group decreased in all analysed variables (-40% in IVUS neointimal volume, -57% in OCT %AS, and -30% in %AS by histology) compared to the progression of neointimal formation observed in the FHS group (+29% in IVUS neointimal volume, +27% in OCT %AS and +43% in %AS by histology).

CONCLUSION

The pattern of neointimal formation following BMS implantation in the FHS follows a progressive course that does not occur in the DS. Therefore, by providing a progressive neointimal biological response to BMS implantation, the FHS could serve as an ideal efficacy model for the validation of drug eluting stent technologies.

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.

Local delivery of gene vectors from bare-metal stents by use of a biodegradable synthetic complex inhibits in-stent restenosis in rat carotid arteries

BACKGROUND

Local drug delivery from polymer-coated stents has demonstrated efficacy for preventing in-stent restenosis; however, both the inflammatory effects of polymer coatings and concerns about late outcomes of drug-eluting stent use indicate the need to investigate innovative approaches, such as combining localized gene therapy with stent angioplasty. Thus, we investigated the hypothesis that adenoviral vectors (Ad) could be delivered from the bare-metal surfaces of stents with a synthetic complex for reversible vector binding.

METHODS AND RESULTS

We synthesized the 3 components of a gene vector binding complex: (1) A polyallylamine bisphosphonate with latent thiol groups (PABT), (2) a polyethyleneimine (PEI) with pyridyldithio groups for amplification of attachment sites [PEI(PDT)], and (3) a bifunctional (amine- and thiol-reactive) cross-linker with a labile ester bond (HL). HL-modified Ad attached to PABT/PEI(PDT)-treated steel surfaces demonstrated both sustained release in vitro over 30 days and localized green fluorescent protein expression in rat arterial smooth muscle cell cultures, which were not sensitive to either inhibition by neutralizing anti-Ad antibodies or inactivation after storage at 37 degrees C. In rat carotid studies, deployment of steel stents configured with PABT/PEI(PDT)/HL-tethered adenoviral vectors demonstrated both site-specific arterial Ad(GFP) expression and adenovirus-luciferase transgene activity per optical imaging. Rat carotid stent delivery of adenovirus encoding inducible nitric oxide synthase resulted in significant inhibition of restenosis.

CONCLUSIONS

Reversible immobilization of adenovirus vectors on the bare-metal surfaces of endovascular stents via a synthetic complex represents an efficient, tunable method for sustained release of gene vectors to the vasculature.

Cells of primarily extravascular origin in neointima formation following stent implantation: coordinated expression of endothelial progenitor, dendritic and neural crest-derived cells

OBJECTIVES

In-stent restenosis due to neointima formation is a major limitation following stent implantation. Recently, several studies reported mobilization of primarily extravascular cells to the arterial sites after balloon angioplasty. Therefore, the goal of the present study was to assess the coordinated neointimal expression of endothelial progenitor, dendritic and neural crest-derived cells after stent implantation.

METHODS

Male minipigs underwent stent implantation in abdominal aortic segments. Animals were sacrificed at 1, 7, 14, 30, 60 or 90 days. Cross sections of the injured vessels were obtained for immunohistochemistry using specific antibodies for the detection of endothelial progenitor (CD133), dendritic (S100) and neural crest-derived cells (GFAP), as well as monocytes/macrophages (CD14) and T lymphocytes (CD3).

RESULTS

As a key finding, frequency of CD133, S100, GFAP, CD14 and CD3 (18.5 +/- 3.6, 14.9 +/- 1.8, 10.6 +/- 1.1, 40.2 +/- 8.3 and 5.0 +/- 0.6%, respectively) in neointima was maximal at day 7. With ongoing neointima enlargement, expression of these cells decreased. In advanced neointima, labeled cells were predominantly localized at luminal and stented sites. Media showed almost no immunoreactivity of the markers studied, whereas adventitial zones of neovascularization revealed some signals.

CONCLUSIONS

Endothelial progenitor, dendritic, neural crest-derived and inflammatory cells are consistently recruited into arterial neointima, mostly at early time points after stent implantation.

Pathophysiology of coronary artery in-stent restenosis

In-stent restenosis reflects the interaction of a cascade of molecular and cellular events occurring within the vessel wall. Coronary stenting induces localized injury to the vessel wall, which leads to the release of thrombogenic, vasoactive, and lymphocytes mitogenic factors that result in processes causing re-narrowing at the injured site. Three major processes have been identified that lead to the in-stent restenosis: neointimal hyperplasia, elastic recoil, and negative arterial remodeling. The most important one is intimal hyperplasia. As the time course of neointimal hyperplasia is unknown, a causal relationship between the development of new blood vessels and clinical restenosis cannot be firmly established.

The cell cycle: a critical therapeutic target to prevent vascular proliferative disease

Percutaneous coronary intervention is the preferred revascularization approach for most patients with coronary artery disease. However, this strategy is limited by renarrowing of the vessel by neointimal hyperplasia within the stent lumen (in-stent restenosis). Vascular smooth muscle cell proliferation is a major component in this healing process. This process is mediated by multiple cytokines and growth factors, which share a common pathway in inducing cell proliferation: the cell cycle. The cell cycle is highly regulated by numerous mechanisms ensuring orderly and coordinated cell division. The present review discusses current concepts related to regulation of the cell cycle and new therapeutic options that target aspects of the cell cycle.

Restenosis after percutaneous angioplasty: the role of vascular inflammation

Restenosis after endovascular treatment of atherosclerotic lesions in the peripheral, cerebrovascular, and coronary circulation is the major drawback of this minimally invasive technique. Although certain advances have been made during recent years to improve patency rates after percutaneous angioplasty, restenosis remains a challenging clinical problem. Understanding factors that contribute to the pathophysiology of late lumen loss is an effective strategy to improving patients' postangioplasty outcome. Vascular inflammation after balloon angioplasty or stent implantation has been identified as a cornerstone of the restenotic process, and several markers of inflammation have been referred to as potential predictors of outcome. This article reviews recent findings on the issue of inflammation and restenosis after percutaneous angioplasty with special attention given to the role of inflammatory parameters as markers for the restenosis risk in the peripheral vessel area.

Bisphosphonate-mediated gene vector delivery from the metal surfaces of stents

The clinical use of metallic expandable intravascular stents has resulted in improved therapeutic outcomes for coronary artery disease. However, arterial reobstruction after stenting, in-stent restenosis, remains an important problem. Gene therapy to treat in-stent restenosis by using gene vector delivery from the metallic stent surfaces has never been demonstrated. The present studies investigated the hypothesis that metal-bisphosphonate binding can enable site-specific gene vector delivery from metal surfaces. Polyallylamine bisphosphonate (PAA-BP) was synthesized by using Michael addition methodology. Exposure to aqueous solutions of PAA-BP resulted in the formation of a monomolecular bisphosphonate layer on metal alloy surfaces (steel, nitinol, and cobalt-chromium), as demonstrated by x-ray photoelectron spectroscopy. Surface-bound PAA-BP enabled adenoviral (Ad) tethering due to covalent thiol-binding of either anti-Ad antibody or a recombinant Ad-receptor protein, D1. In arterial smooth muscle cell cultures, alloy samples configured with surface-tethered Ad were demonstrated to achieve site-specific transduction with a reporter gene, (GFP). Rat carotid stent angioplasties using metal stents exposed to aqueous PAA-BP and derivatized with anti-knob antibody or D1 resulted in extensive localized Ad-GFP expression in the arterial wall. In a separate study with a model therapeutic vector, Ad-inducible nitric oxide synthase (iNOS) attached to the bisphosphonate-treated metal stent surface via D1, significant inhibition of restenosis was demonstrated (neointimal/media ratio 1.68 +/- 0.27 and 3.4 +/- 0.35; Ad-iNOS vs. control, P < 0.01). It is concluded that effective gene vector delivery from metallic stent surfaces can be achieved by using this approach.

Drug-Eluting Coronary Stents

The introduction and widespread use of coronary stents have been the most important advancement in the percutaneous treatment of coronary artery disease since the introduction of balloon angioplasty. Coronary artery stents reduce the rate of angiographic and clinical restenosis compared to balloon angioplasty. This angiographic restenosis was further reduced with the introduction of drug-eluting stents and hence further reduction in the frequency of major adverse cardiac events. Herein we present a comprehensive and up-to-date review about the use of drug-eluting stents in the treatment of coronary artery disease.

Comparison of levels of inflammatory markers and hemostatic factors in the patients with and without peripheral arterial disease

INTRODUCTION

Peripheral arterial disease is one aspect of atherosclerosis, a disease associated with both inflammation and hypercoagulability. Many recent studies have focused on the diversity of mechanisms by which inflammation can promote blood clotting. However, the relationship between plasma concentrations of inflammatory and hemostatic markers and the severity of atherosclerosis is not yet well studied. We want to determine the relations among selected D-dimer, C-reactive protein, fibrinogen, prothrombin time and serum amyloid A, and the ankle brachial index in patients with and without peripheral arterial disease.

MATERIALS AND METHODS

In a prospective cohort study, 45 consecutive patients with peripheral arterial disease of ankle brachial index<0.90, and 44 patients without peripheral arterial disease of ankle brachial index 0.90 to 1.50 were included. D-dimer, fibrinogen, C-reactive protein, serum amyloid A, and prothrombin time were measured at the recruitment.

RESULTS

Median values of serum amyloid A, D-dimer, and C-reactive protein were significantly higher in the peripheral arterial disease group than in those without peripheral arterial disease group (p<0.001). The patients with PAD had moderately higher fibrinogen levels than without PAD (p<0.01). Prothrombin time levels were normal in both groups. In multivariable regression analyses adjusting for all blood factors as well as potential confounders, patients with peripheral arterial disease, levels of serum amyloid A, and C-reactive protein showed a highly significant, inverse association with the ankle brachial index. D-dimer and fibrinogen level increase were also found to be related to lower ankle brachial index, while no association was observed between prothrombin time levels.

CONCLUSIONS

Higher C-reactive protein, serum amyloid A, and D-dimer levels are showing positive association with the presence of peripheral arterial disease. C-reactive protein and serum amyloid A levels are direct relations between the ankle brachial index and the extent of vascular inflammation.

Eosinophilic infiltration in restenotic tissue following coronary stent implantation

OBJECTIVES

The aim of our study was to compare the histopathological features of restenotic tissue after balloon angioplasty and after stent placement. We emphasized on specific types of inflammatory cells to evaluate the type of tissue immune response in both situations.

METHODS

A total of 32 patients underwent elective directional coronary atherectomy; 16 patients had restenosis after balloon angioplasty, 16 patients had in-stent restenosis (ISR). Atherectomy specimens were stained with antibodies against T cells, eosinophils, smooth muscle cell actin, macrophages and with antibodies against T cell activation markers. Quantitative morphometric analysis was performed using image analysis software.

RESULTS

In-stent restenotic tissue contained more smooth muscle cells (P < 0.001), anti-CD3 positive T cells (P < 0.001) and eosinophils (P = 0.012). Anti-CD40L positive activated T cells were more numerous in ISR lesions (P = 0.003) and were frequently clustered around stent imprints in the tissue. Five ISR specimens contained grossly visible stent fragments amidst the restenotic tissue. In all cases of balloon restenosis, T cells and eosinophils (if present) were concentrated around lipid rich tissue.

CONCLUSIONS

Our study indicates involvement of inflammatory responses in both types of restenosis, with significantly more eosinophils encountered in case of in-stent restenosis. In contrast with clustering of inflammatory cells around stent struts after stent placement, the inflammatory cells in balloon restenosis were located in association with lipid rich tissue, suggesting different inflammatory triggers in balloon restenosis and in-stent restenosis.

Calcification and proteoglycan accumulation following balloon angioplasty and stenting

PURPOSE

To examine in a porcine model if a correlation exists between calcification and the hyperplastic response of arteries to balloon angioplasty and stenting.

METHODS

Eleven Sinclair miniature swine on an atherogenic diet underwent balloon angioplasty or endovascular stenting in nondiseased external iliac arteries using standard procedures. Ninety days postoperatively, the animals were euthanized, and histological sections of the dilated, stented, and control arteries were examined for evidence of calcification and increased proteoglycan accumulation.

RESULTS

An increase in proteoglycan accumulation and the loss of integrity of the internal elastic lamina were observed in both the dilated and stented arteries. Diffuse calcification was seen in the media/neomedia of both groups, and large calcium salt deposits were observed in the dilated arteries at the site of the internal elastic lamina and near the stent struts in stented arteries.

CONCLUSIONS

Internal elastic lamina loss of integrity appears to be related to an increase in proteoglycans through the formation of a neointima, and the arterial hyperplastic response to balloon angioplasty and stenting seems to lead to calcification.

Evolving Strategies for the Prevention and Treatment of Coronary Restenosis

Percutaneous coronary intervention has become an increasingly attractive alternative to medical therapy and surgical revascularization for the treatment of coronary artery disease. Over 1.5 million interventional procedures are performed annually worldwide, with the rate of procedures performed continuing to rise dramatically. Restenosis following percutaneous coronary intervention occurs at rates of 20% to 40% and has remained the Achilles heel of the procedure. Numerous early attempts at the prevention of restenosis with oral pharmacologic agents, such as antithrombotic therapies, lipid lowering agents, vasodilators, and growth factor inhibitors, failed to show benefit in clinical trials. The introduction of intracoronary stents resulted in a 30% reduction in restenosis rates by abolishing the early vessel recoil following angioplasty. However, as more complex lesions underwent percutaneous coronary intervention with stenting, rates of “in-stent” restenosis remained high (20% to 30%). With technologic advances and greater understanding of vascular pathobiology, novel therapeutic strategies, such as local delivery of ionizing radiation, immunosuppressive agents, and gene therapy, have been deployed to prevent coronary restenosis. In addition, a number of mechanical and radiation-based strategies have been used to treat those patients who develop restenosis. This review considers these emerging strategies for the prevention and treatment of restenosis.

Obstruction of St Jude Medical valves in the aortic position: histology and immunohistochemistry of pannus

OBJECTIVE

This study aims to reveal the morphological, histological, and immunohistochemical mechanism of pannus formation using resected pannus tissue from patients with prosthetic valve dysfunction.

METHOD

Eleven patients with prosthetic valve (St Jude Medical valve) dysfunction in the aortic position who underwent reoperation were studied. We used specimens of resected pannus for histological staining (hematoxylin and eosin, Grocott's, azan, elastica van Gieson) and immunohistochemical staining (transforming growth factor-beta, transforming growth factor-beta receptor 1, alpha-smooth muscle actin, desmin, epithelial membrane antigen, CD34, factor VIII, CD68KP1, matrix metalloproteinase-1, matrix metalloproteinase-3, and matrix metalloproteinase-9).

RESULTS

Pannus without thrombus was observed at the periannulus of the left ventricular septal side; it extended into the pivot guard, interfering with the movement of the straight edge of the leaflet. The histological staining demonstrated that the specimens were mainly constituted with collagen and elastic fibrous tissue accompanied by endothelial cells, chronic inflammatory cells infiltration, and myofibroblasts. The immunohistochemical findings showed significant expression of transforming growth factor-beta, transforming growth factor-beta receptor 1, CD34, and factor VIII in the endothelial cells of the lumen layer; strong transforming growth factor-beta receptor 1, alpha-smooth muscle actin, desmin, and epithelial membrane antigen in the myofibroblasts of the media layer; and transforming growth factor-beta, transforming growth factor-beta receptor 1, and CD68KP1 in macrophages of the stump lesion.

CONCLUSIONS

Pannus appeared to originate in the neointima in the periannulus of the left ventricular septum. The structure of the pannus consisted of myofibroblasts and an extracellular matrix such as collagen fiber. The pannus formation after prosthetic valve replacement may be associated with a process of periannular tissue healing via the expression of transforming growth factor-beta.

Effects of candesartan and probucol on restenosis after coronary stenting: results of insight of stent intimal hyperplasia inhibition by new angiotensin II receptor antagonist (ISHIN) trial

The purpose of this study was to determine whether candesartan and its combination with probucol reduce restenosis after coronary stenting. A total of 132 patients who successfully underwent stenting were randomly assigned to a control group (n=45), a candesartan group (8 mg daily, n=43), or a candesartan plus probucol group (+ probucol 500 mg daily, n=44). No differences in late loss were observed between the control and candesartan groups. In the candesartan plus probucol group, late loss was significantly smaller than in the control and candesartan groups (p=0.003, 0.015). The restenosis rate was 27% in the control group, 26% in the candesartan group (p>0.99), and 11% in the candesartan plus probucol group (p=0.104 vs the control group and p=0.103 vs the candesartan group). Intravascular ultrasound revealed no differences in stent area among the 3 groups, and no differences in lumen area or in intimal hyperplasia area between the control and candesartan groups. However, the intimal hyperplasia area in the candesartan plus probucol group was significantly less than that in the control and candesartan groups (p<0.001, p<0.001). This study demonstrated that candesartan failed to inhibit the neointimal hyperplasia and although the combination treatment did reduce neointimal hyperplasia, it did not statistically reduce the restenosis rate.

Restenosis after femoropopliteal PTA and elective stent implantation: predictive value of monocyte counts

PURPOSE

To investigate the association of baseline peripheral blood monocyte counts and restenosis after femoropopliteal percutaneous transluminal angioplasty (PTA) and PTA plus elective stent implantation.

METHODS

Three hundred thirty consecutive patients (170 men; median age 71 years, interquartile range 61-78) with peripheral artery disease underwent femoropopliteal PTA (n=258) or PTA plus elective stent implantation (n=72). Multivariate Cox regression analysis was used to determine the predictive value of baseline peripheral blood monocyte counts on the rate of restenosis (> or =50% luminal reduction) in follow-up.

RESULTS

Cumulative patency at 6 and 12 months was 55% and 39% after PTA and 70% and 41% after elective stenting, respectively (p=0.19). Pretreatment monocyte counts (in tertiles) were associated with restenosis after PTA (p=0.002) and stent implantation (p=0.02). Compared to patients with monocyte counts <0.3x10(9)/L (lower tertile, n=128), patients with monocytes from 0.3 to 0.4x10(9)/L (middle tertile, n=91) had a 1.8-fold increased adjusted risk for restenosis (95% CI 1.1 to 2.8, p=0.01). Patients with monocytes >0.4x10(9)/L (upper tertile, n=87) had a 2.3-fold increased adjusted risk (95% CI 1.4 to 3.5, p<0.0001).

CONCLUSIONS

Baseline monocyte counts were associated with restenosis after femoropopliteal PTA and elective stent implantation, suggesting that circulating monocytes play a pivotal role in the development of recurrent lumen narrowing.

Endovascular revascularization below the knee: 6-month results and predictive value of C-reactive protein level

PURPOSE

To determine the association between pre- and postintervention serum C-reactive protein (CRP) levels and 6-month restenosis after endovascular treatment of atherosclerotic lesions in arteries below the knee.

MATERIALS AND METHODS

Eighty-nine patients with peripheral arterial disease underwent primary successful percutaneous transluminal angioplasty (PTA) of the distal popliteal, anterior tibial, posterior tibial, and fibular arteries. Six-month patency was evaluated with the ankle brachial index (ABI) and color-coded duplex ultrasonography (US). The association between restenosis and preintervention and 48-hour postintervention CRP levels was assessed with multiple logistic regression analysis.

RESULTS

ABI improved from a preintervention median of 0.54 to a postintervention median of 0.75 (P <.001). The primary technical success rate was 94% (100 of 106). In 50 patients, a suboptimal technical result was achieved with 30%-40% residual stenosis at the dilated segment. The median ABI at 6 months was 0.65, and it was inversely correlated with preintervention (r = -0.27, P =.009) and 48-hour postintervention (r = -0.40, P <.001) CRP levels. With duplex US at 6 months, restenosis (> or =50%) occurred in 36 patients. Patients with a preintervention CRP level of 0.23-0.92 mg/dL (2.3-9.2 mg/L) had a 3.7-fold increased adjusted risk for restenosis (P =.05); patients with a preintervention CRP level greater than 0.92 mg/dL (9.2 mg/L) had a 4.7-fold increased adjusted risk (P =.03). Postintervention CRP values greater than 2.42 mg/dL (24.2 mg/L) were associated with a 10.7-fold adjusted risk for restenosis (P =.002). Suboptimal PTA result was the only other parameter associated with an increased risk for restenosis (odds ratio, 3.7; P =.03).

CONCLUSION

Pre- and postintervention CRP levels were associated with restenosis after PTA of the distal popliteal and tibioperoneal arteries, which indicates that inflammation plays a crucial role in the pathophysiology of this process.

Acute-phase response after stent implantation in the carotid artery: association with 6-month in-stent restenosis

PURPOSE

To determine the prognostic importance of periintervention serum levels of acute-phase reactants in 6-month restenosis after stent implantation in the carotid artery.

MATERIALS AND METHODS

One hundred eight consecutive patients with 70% or greater stenosis of the internal carotid artery (ICA) according to the North American Symptomatic Carotid Endarterectomy Trial criteria underwent successful stent implantation in the ICA in a prospective cohort study. Six-month patency was evaluated at color-coded duplex ultrasonography. The association between in-stent restenosis (> or =50%, North American Symptomatic Carotid Endarterectomy Trial criterion) and C-reactive protein (CRP) and serum amyloid A levels at baseline and at 24 and 48 hours after intervention was assessed.

RESULTS

Restenosis was found in 15 (14%) patients within 6 months. CRP level at 48 hours, exemplary for the postintervention acute-phase response, was significantly (P =.01) associated with 6-month restenosis by using multiple logistic regression analysis. Recurrent stenosis after prior stent implantation in the carotid artery (odds ratio, 9.2; 95% CI: 1.6, 53.2; P =.01) and residual stenosis of 10%-30% after stent implantation (odds ratio, 9.7; 95% CI: 1.6, 59.3; P =.01) were independent clinical predictors of restenosis.

CONCLUSION

Extent of vascular inflammatory response after stent implantation in the carotid artery measured with acute-phase reactants is associated with 6-month patency. Recurrent stenosis after prior stent implantation and initial suboptimal technical result seem to be clinically relevant predictors of postangioplasty outcome.