A controlled trial of corticosteroids to prevent restenosis after coronary angioplasty. M-HEART Group

The safety of pulse corticosteroid therapy- Systematic review and meta-analysis

OBJECTIVE

To amass all available evidence from randomized controlled trials regarding the safety of pulse corticosteroids therapy, in order to establish its safety.

PATIENTS AND METHODS

All electronic databases from 1/1966 up to 02/2019 were reviewed to find all randomized controlled trials comparing pulse corticosteroids to oral corticosteroids or to placebo/no treatment. Two reviewers independently extracted and recorded data regarding type of corticosteroid treatment, dosages, length of treatment and follow-up. Risk ratios (RR) with 95% (CI) for differences between pulse corticosteroids and comparator were pooled using a fixed effect meta-analysis. The primary outcome was occurrence of severe adverse events (SAEs). Secondary outcomes included any adverse events (AEs), AEs requiring discontinuation, AEs per system involved and all-cause mortality.

RESULTS

A total of 64 trials were included: 18 trials which compared pulse corticosteroids to oral corticosteroids and 46 trials which compared pulse corticosteroids to placebo/no intervention. Pulse corticosteroids was not associated with increased risk for SAEs for both comparators: RR 0.77 (95% CI 0.52-1.14), and RR 0.99 (95% CI 0.93-1.06), respectively. Sensitivity analysis based on adequate allocation concealment and use of a valid AE grading did not alter the results. Subgroup analysis revealed no increased risk of specific SAEs or AEs with pulse corticosteroids compared to oral corticosteroids.

CONCLUSION

Pulse corticosteroids was not associated with an increase risk of SAEs and should be regarded as safe.

Species-specific regulation of angiogenesis by glucocorticoids reveals contrasting effects on inflammatory and angiogenic pathways

Glucocorticoids are potent inhibitors of angiogenesis in the rodent in vivo and in vitro but the mechanism by which this occurs has not been determined. Administration of glucocorticoids is used to treat a number of conditions in horses but the angiogenic response of equine vessels to glucocorticoids and, therefore, the potential role of glucocorticoids in pathogenesis and treatment of equine disease, is unknown. This study addressed the hypothesis that glucocorticoids would be angiostatic both in equine and murine blood vessels.The mouse aortic ring model of angiogenesis was adapted to assess the effects of cortisol in equine vessels. Vessel rings were cultured under basal conditions or exposed to: foetal bovine serum (FBS; 3%); cortisol (600 nM), cortisol (600nM) plus FBS (3%), cortisol (600nM) plus either the glucocorticoid receptor antagonist RU486 or the mineralocorticoid receptor antagonist spironolactone. In murine aortae cortisol inhibited and FBS stimulated new vessel growth. In contrast, in equine blood vessels FBS alone had no effect but cortisol alone, or in combination with FBS, dramatically increased new vessel growth compared with controls. This effect was blocked by glucocorticoid receptor antagonism but not by mineralocorticoid antagonism. The transcriptomes of murine and equine angiogenesis demonstrated cortisol-induced down-regulation of inflammatory pathways in both species but up-regulation of pro-angiogenic pathways selectively in the horse. Genes up-regulated in the horse and down-regulated in mice were associated with the extracellular matrix. These data call into question our understanding of glucocorticoids as angiostatic in every species and may be of clinical relevance in the horse.

Inflammation and atherosclerosis--revisited

Atherogenesis has been traditionally viewed as a metabolic disease representing arterial obstruction by fatty deposits in its wall. Today, it is believed that atherogenesis involves highly specific biochemical and molecular responses with constant interactions between various cellular players. Despite the presence of inflammatory reaction in each and every step of atherosclerosis from its inception to terminal manifestation, the cause--effect relationship of these 2 processes remains unclear. In this article, we have attempted to review the role of inflammation in the development of atherosclerosis and in its major complication--coronary heart disease.

Modulation of 11β-hydroxysteroid dehydrogenase as a strategy to reduce vascular inflammation

Atherosclerosis is a chronic inflammatory disease in which initial vascular damage leads to extensive macrophage and lymphocyte infiltration. Although acutely glucocorticoids suppress inflammation, chronic glucocorticoid excess worsens atherosclerosis, possibly by exacerbating systemic cardiovascular risk factors. However, glucocorticoid action within the lesion may reduce neointimal proliferation and inflammation. Glucocorticoid levels within cells do not necessarily reflect circulating levels due to pre-receptor metabolism by 11β-hydroxysteroid dehydrogenases (11β-HSDs). 11β-HSD2 converts active glucocorticoids into inert 11-keto forms. 11β-HSD1 catalyses the reverse reaction, regenerating active glucocorticoids. 11β-HSD2-deficiency/inhibition causes hypertension, whereas deficiency/inhibition of 11β-HSD1 generates a cardioprotective lipid profile and improves glycemic control. Importantly, 11β-HSD1-deficiency/inhibition is atheroprotective, whereas 11β-HSD2-deficiency accelerates atherosclerosis. These effects are largely independent of systemic risk factors, reflecting modulation of glucocorticoid action and inflammation within the vasculature. Here, we consider whether evidence linking the 11β-HSDs to vascular inflammation suggests these isozymes are potential therapeutic targets in vascular injury and atherosclerosis.

Perivascular delivery of neomycin inhibits the activation of NF-κB and MAPK pathways, and prevents neointimal hyperplasia and stenosis after arterial injury

The nuclear transcription factor kappaB (NF-kappaB) is a cytoplasmic dimer that, as the family of mitogen-activated protein kinase (MAPK), can directly regulate the expression of early genes and genes involved in the stress response, following a variety of physiological or pathological stimuli. Both of them stimulate the transcription of many proteins, which are considered important during inflammation. A crucial role has been assigned to these factors in cellular proliferation and in neointimal hyperplasia secondary to the endothelial lesion of arterial vessels. On the other hand, it has been described that neomycin can have an inhibitory function on tumor cell proliferation, through the inhibition of different intracellular pathways of signaling, among them the NF-kappaB and MAPK pathways. Rat common carotid artery was subjected to balloon angioplasty. Neomycin sulfate (18 mg) was applied using pluronic acid gel on the adventitial surface of the injured vessel. MAPK and NF-kappaB activation was quantified after 24 hours with immunohistochemical staining. Neointimal formation was quantified after 14 days with morphometry. Immunohistochemistry results demonstrating MAPK and NF-kappaB activation reveal that both transcription factors are activated in the media of the control vessel wall. In contrast, the immunoreactivity for MAPK and NF-kappaB in the sections obtained from arteries treated with neomycin over 24 hours was insufficient or nonexistent. Treatment with neomycin on adventitia over 14 days in arteries on which angioplasty was performed shows a neointimal index (intimal area/medial area) decrease of 71% in comparison with arteries that were not treated. The adventitial neomycin treatment over 14 days produces a very significant increase (287.5%; p<0.0001) in the arterial luminal circumference in comparison with arteries treated with vehicle. These results support the theory that neomycin plays an important role against neointimal hyperplasia through the inhibition of MAPK and NF-kappaB activation.

Intravascular stents

Intravascular stents have been developed to address acute arterial closure and restenosis, the major limitations of percutaneous transluminal coronary angioplasty (PTCA). Metallic stents in human clinical trials have shown efficacy in treating acute closure and, in selected patients, lowering the restenosis rate. This review delineates the characteristics of the ideal stent and examines ongoing clinical trials that are evaluating various stent prototypes. Developmental stents that use radiopaque and bioabsorbable materials are presented. The potential role for intravascular stents as vehicles for localized drug delivery and gene therapy is discussed.

Nanomedicine for the prevention, treatment and imaging of atherosclerosis

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in developed countries, with an increasing prevalence due to an aging population. The pathology underpinning CVD is atherosclerosis, a chronic inflammatory state involving the arterial wall. Accumulation of low density lipoprotein (LDL) laden macrophages in the arterial wall and their subsequent transformation into foam cells lead to atherosclerotic plaque formation. Progression of atherosclerotic lesions may gradually lead to plaque related complications and clinically manifest as acute vascular syndromes including acute myocardial or cerebral ischemia. Nanotechnology offers emerging therapeutic strategies, which may have advantage overclassical treatments for atherosclerosis. In this review, we present the potential applications of nanotechnology toward prevention, identification and treatment of atherosclerosis.

AMPKα2 deletion exacerbates neointima formation by upregulating Skp2 in vascular smooth muscle cells

RATIONALE

Adenosine monophosphate-activated protein kinase (AMPK), a metabolic and redox sensor, is reported to suppress cell proliferation of nonmalignant and tumor cells. Whether AMPKα alters vascular neointima formation induced by vascular injury is unknown.

OBJECTIVE

The aim of this study was to determine the roles of AMPKα in the development of vascular neointima hyperplasia and to elucidate the underlying mechanisms.

METHODS AND RESULTS

Vascular smooth muscle cell (VSMC) proliferation and neointimal hyperplasia were evaluated in cultured VSMCs and wire-injured mouse carotid arteries from wild-type (WT, C57BL/6J), AMPKα2(-/-), and AMPKα1(-/-) mice. Mouse VSMCs derived from aortas of AMPKα2(-/-) mice exhibited increased proliferation compared with either WT or AMPKα1(-/-) VSMCs. Further, deletion of AMPKα2 but not AMPKα1 reduced the level of p27(Kip1), a cyclin-dependent kinase inhibitor, and increased the level of S-phase kinase-associated protein 2 (Skp2), a known E3 ubiquitin ligase for p27(Kip1), through activation of p52 nuclear factor kappa B (NF-κB)-2. Moreover, either pharmacological (ie, through compound C) or genetical (ie, through AMPKα2-specific siRNA) inhibition of AMPK decreased p27(Kip1) levels but increased the abundance of Skp2 in human VSMCs. Furthermore, gene silencing of Skp2 reversed the levels of p27(Kip1) and VSMCs proliferation. Finally, neointima formation after mechanical arterial injury was increased in AMPKα2(-/-) but not AMPKα1(-/-) mice.

CONCLUSIONS

These findings indicate that deletion of AMPKα2 through p52-Skp2-mediated ubiquitination and degradation of p27(Kip1) accentuates neointimal hyperplasia in response to wire injury.

Immunosuppressive therapy with oral prednisone to prevent restenosis after PCI. A multicenter randomized trial

BACKGROUND

Prednisone at immunosuppressive doses after stenting has shown remarkable efficacy in reducing ischemic recurrences in nondiabetic patients with high post-procedural levels of C-reactive protein; the study aim was to compare the clinical outcome obtained in a control group of patients treated with bare metal stents versus 2 other study groups--bare metal stent plus oral prednisone or drug eluting stents--assuming similar optimal adjunctive medical treatment.

METHODS

Five tertiary Italian hospitals enrolled 375 nondiabetic patients with coronary artery disease and no contraindications to dual antiplatelet treatment or corticosteroid therapy in a randomized, controlled study performed between 2007 and 2009. Patients were allocated into 3 study groups: bare metal stents (controls), bare metal stents followed by a 40-day prednisone treatment, or drug-eluting stents. The primary endpoint was the event-free survival of cardiovascular death, myocardial infarction, and recurrence of ischemia needing repeated target vessel revascularization at 1 year as adjudicated by an independent clinical events committee.

RESULTS

One-year follow-up was obtained in all patients. Patients receiving bare metal stents alone as compared to those treated with prednisone or drug-eluting stents had lower event-free survival; the primary endpoint was 80.8% in controls compared to 88.0% in the prednisone and 88.8% in the drug-eluting stent groups, respectively (P=.04 and .006).

CONCLUSION

Compared with bare metal stents alone, prednisone treatment after bare metal stents or drug-eluting stent implantation result in a better event-free survival at 1 year.

Therapeutic manipulation of glucocorticoid metabolism in cardiovascular disease

The therapeutic potential for manipulation of glucocorticoid metabolism in cardiovascular disease was revolutionized by the recognition that access of glucocorticoids to their receptors is regulated in a tissue-specific manner by the isozymes of 11beta-hydroxysteroid dehydrogenase. Selective inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 have been shown recently to ameliorate cardiovascular risk factors and inhibit the development of atherosclerosis. This article addresses the possibility that inhibition of 11beta-hydroxsteroid dehydrogenase type 1 activity in cells of the cardiovascular system contributes to this beneficial action. The link between glucocorticoids and cardiovascular disease is complex as glucocorticoid excess is linked with increased cardiovascular events but glucocorticoid administration can reduce atherogenesis and restenosis in animal models. There is considerable evidence that glucocorticoids can interact directly with cells of the cardiovascular system to alter their function and structure and the inflammatory response to injury. These actions may be regulated by glucocorticoid and/or mineralocorticoid receptors but are also dependent on the 11beta-hydroxysteroid dehydrogenases which may be expressed in cardiac, vascular (endothelial, smooth muscle) and inflammatory (macrophages, neutrophils) cells. The activity of 11beta-hydroxysteroid dehydrogenases in these cells is dependent upon differentiation state, the action of pro-inflammaotory cytokines and the influence of endogenous inhibitors (oxysterols, bile acids). Further investigations are required to clarify the link between glucocorticoid excess and cardiovascular events and to determine the mechanism through which glucocorticoid treatment inhibits atherosclerosis/restenosis. This will provide greater insights into the potential benefit of selective 11beta-hydroxysteroid dehydrogenase inhibitors in treatment of cardiovascular disease.

Avoiding restenosis: is there a role for glucocorticoids in the drug-eluting stent era?

Restenosis is an important limitation of percutaneous coronary interventions (PCI). In-stent restenosis is mainly due to neointimal hyperplasia, a proliferative process modulated by inflammatory mechanisms. Numerous technical and pharmacological means have been tested to reduce restenosis rates, with frequently disappointing clinical results. Drug-eluting stents (DES) have demonstrated a high efficacy in reducing restenosis, but there are some associated problems that limit its generalized utilization. Glucocorticoids (GC), as potent anti-inflammatory agents, may exert beneficial effects on neointimal proliferation. Clinical studies with oral and intracoronary GC therapy have demonstrated reduction in restenosis rates in selected patients. Although further investigations are warranted, GC might have a potential role for restenosis prevention in selected cases.

A review of the biocompatibility of implantable devices: current challenges to overcome foreign body response

In recent years, a variety of devices (drug-eluting stents, artificial organs, biosensors, catheters, scaffolds for tissue engineering, heart valves, etc.) have been developed for implantation into patients. However, when such devices are implanted into the body, the body can react to these in a number of different ways. These reactions can result in an unexpected risk for patients. Therefore, it is important to assess and optimize the biocompatibility of implantable devices. To date, numerous strategies have been investigated to overcome body reactions induced by the implantation of devices. This review focuses on the foreign body response and the approaches that have been taken to overcome this. The biological response following device implantation and the methods for biocompatibility evaluation are summarized. Then the risks of implantable devices and the challenges to overcome these problems are introduced. Specifically, the challenges used to overcome the functional loss of glucose sensors, restenosis after stent implantation, and calcification induced by implantable devices are discussed.

Glucocorticoids and cardiovascular disease

Chronic excessive activation of glucocorticoid receptors induces obesity, insulin resistance, glucose intolerance, dyslipidaemia and hypertension. Subtle abnormalities of the hypothalamic-pituitary-adrenal axis and/or of tissue sensitivity to glucocorticoids are also associated with these cardiovascular risk factors in patients with the metabolic syndrome. Furthermore, glucocorticoids have direct effects on the heart and blood vessels, mediated by both glucocorticoid and mineralocorticoid receptors and modified by local metabolism of glucocorticoids by the 11beta-hydroxysteroid dehydrogenase enzymes. These effects influence vascular function, atherogenesis and vascular remodelling following intra-vascular injury or ischaemia. This article reviews the systemic and cardiovascular effects of glucocorticoids, and the evidence that glucocorticoids not only promote the incidence and progression of atherogenesis but also modify the recovery from occlusive vascular events and intravascular injury. The conclusion is that manipulation of glucocorticoid action within metabolic and cardiovascular tissues may provide novel therapeutic avenues to combat cardiovascular disease.

Glucocorticoids in the prevention of restenosis after coronary angioplasty: therapeutic potential

Vessel luminal narrowing after percutaneous coronary intervention (PCI) is characterised by platelet aggregation, release of growth factors, inflammatory cell infiltration, medial smooth muscle cell (SMC) proliferation, proteoglycan deposition and extracellular matrix remodelling. It is broadly accepted that the central mechanism at the basis of the whole pathophysiological process of restenosis is inflammation, triggered by vascular injury and activated through autocrine or paracrine mediators. Glucocorticosteroids exert beneficial effects on platelet function, on SMC proliferation and on collagen synthesis as well as inflammatory cell migration and activation, thus interfering with several steps of the cascade leading to neointima formation and subsequent late lumen loss. Initial experiences with systemic administration of glucocorticoids after PCI failed to confirm the expected benefits of this treatment, probably as a result of inadequate dosage and pharmacokinetic calculations. Recently a short-term, high-dose immunosuppressive treatment scheme with oral prednisone has demonstrated remarkable clinical and angiographic results when prednisone was given orally at a dose of 1 mg/kg for 10 days, 0.5 mg/kg for 20 days and 0.25 mg/kg for 15 days. This treatment has dramatically reduced the incidence of clinical vascular events at 1 year compared with controls (relative risk 0.34; 95% CI 0.12, 0.96; p = 0.006) and reduced the incidence of angiographic restenosis below 10% in different clinical and angiographic subsets. Secondary effects of a short course of glucocorticoids are generally minor, predictable and reversible: gastric pain, water and salt retention and worsened hypertension manifest in nearly 10% of patients. The addition of diuretics and acid suppressants before discharge, and the upgrading of antihypertensive medication thereafter, if needed, are useful preventive measures to control these temporary disorders. A routine blood cell count 4 weeks after PCI is advised in patients receiving thienopyridines (clopidogrel or ticlopidine) in addition to prednisone to rule out infrequent haematological dyscrasias. Emerging evidence supports this strategy as a convenient and well tolerated alternative to more expensive and complex revascularisation procedures such as drug eluting stent (DES) implantation or cardiac surgery, provided that the treatment is reserved for carefully selected candidates, i.e. after the exclusion of those with diabetes mellitus, a recent transmural myocardial infarction, or contraindications to the administration of a short-course of high-dose glucocorticosteroids. The recent concerns regarding the long-term safety of first-generation DES and the as yet undetermined duration of dual anti-platelet treatment, further supports the need for a simple pharmacological treatment that can be applied in a large percentage of patients currently treated with PCI. Multicentre randomised studies aimed at defining the efficacy and safety of oral prednisone treatment compared with metallic stents and DES are ongoing, and will become available in upcoming years.

Percutaneous treatment of coronary bifurcations: lesion preparation before provisional bare metal stenting and subsequent immunosuppression with oral prednisone. The IMPRESS-Y study

Aim of the study was to assess the clinical and angiographic efficacy of oral treatment with prednisone at immunosuppressive dosage after percutaneous coronary interventions (PCI) in patients with bifurcation lesions treated with elective bare metal stent (BMS) implantation in the main-branch (MB) and provisional stenting in the side-branch (SB). Twenty-five patients were treated on 29 bifurcation lesions (58 vessel segments). Lesion preparation before stenting was performed with atherectomy in 7 cases, and balloon PCI over double wires in all other cases; none was treated directly with stents. The mean length of stents implanted in the MB was 19.6 +/- 4.9 mm (10-30 mm). Balloon PCI was successful in 23 of 29 SB and provisional stenting was needed in 6 SB (21%). All patients received oral prednisone according to the immunosuppressive protocol previously reported (1 mg/kg/day/10 days, 0.5 mg/kg/day/20 days, 0.25 mg/kg/day/15 days). At 12 months, one patient had recurrence of angina (4%) and two patients underwent repeated target lesion revascularization (8%). No patient died or had stent thrombosis. Quantitative coronary analysis was performed in all patients at 8 months. Global restenosis rate per vessel was 8.6% (5/58), and 17.2% (5/29) per lesion. The restenosis rate and late lumen loss were 3.4% and 0.36 +/- 0.6 mm, and 13.8% and 0.47 +/- 0.46 mm in the MB and the SB, respectively. Single stent implantation in the MB and provisional stenting of the SB is feasible in most cases after adequate lesion preparation. The systemic treatment with oral prednisone after BMS implantation offers good clinical and angiographic results even in the difficult setting of bifurcation lesions.

Comparison of efficacy and safety of lower-dose to higher-dose oral prednisone after percutaneous coronary interventions (the IMPRESS-LD study)

This study assessed clinical and angiographic efficacies of oral treatment with prednisone at low-dose (LD) versus the previous high-dose (HD) immunosuppressive dosage used after percutaneous coronary interventions (PCIs) with bare metal stents in patients with multivessel coronary artery disease. Forty-three patients with multivessel disease successfully treated with multiple PCIs were matched to the previous HD IMPRESS-2/MVD study population. The 43 patients were treated for 103 coronary stenoses and received 30-day oral prednisone treatment (LD group 1 mg/kg for 5 days, 0.5 mg/kg for 10 days, 0.25 mg/kg for 15 days) and were compared retrospectively with the 43 patients in the HD IMPRESS-2/MVD study with 116 treated coronary lesions (HD group 1 mg/kg for 10 days, 0.5 mg/kg for 20 days, 0.25 mg/kg for 15 days). The primary clinical end point was 12-month event-free survival rate (defined as freedom from death, myocardial infarction, and need for target vessel revascularization). The secondary end point was angiographic restenosis at 8 months assessed by quantitative coronary angiography. Event-free survival rates were 74% and 93% in the LD and HD groups, respectively (relative risk 4.6, 95% confidence interval 1.18 to 17.8, p = 0.019). Restenosis was observed in 4 lesions (4%) in the HD group and in 20 lesions (22%) in the LD group (p <0.001). Mean late lumen loss was 0.61 +/- 0.35 mm, and the loss index was 31.3 +/- 21.6% in the HD group compared with 0.87 +/- 0.61 mm and 52.03 +/- 25.1% in the LD group (p = 0.03 and 0.02, respectively). In conclusion, antirestenotic efficacy of oral treatment with prednisone after conventional PCI is dose sensitive. A 50% dose decrease in oral prednisone, as tested in this study, is less effective than the previously tested HD IMPRESS therapeutic scheme.

The favorable clinical and angiographic outcomes of a high-dose dexamethasone-eluting stent: randomized controlled prospective study

BACKGROUND

Previous studies with dexamethasone-eluting stents could not elucidate the role of dexamethasone in the prevention of neointimal hyperplasia because they did not compare their results with a control group. We prospectively evaluated the clinical and angiographic outcomes of dexamethasone-eluting stents, comparing them with unloaded stents of an identical design.

METHODS

A total of 92 patients (98 lesions) were randomly assigned to the dexamethasone group (67 patients, 71 lesions) or control group (25 patients, 27 lesions). The inclusion criteria for a stent implantation were a de novo lesion with a diameter of 2.60 to 4.0 mm. BiodivYsio Drug Delivery phosphorylcholine-coated stents (Biocompatibles Ltd, Galway, Ireland) were immersed in a 20-mg/mL dexamethasone solution, yielding a total dexamethasone dose of 0.5 microg/mm2 per stent.

RESULTS

The total major adverse cardiac events rate at 12 months was significantly lower in the dexamethasone group, as compared with the control group (10.4% [7/67] vs 28.0% [7/25], P = .037). The binary restenosis rate at 6 months was 11.9% (7/59) in the dexamethasone group and 42.9% (9/21) in the control group (P = .002). The use of dexamethasone-eluting stents was the only independent predictor for the major adverse cardiac event at 12 months (relative risk 0.20, 95% CI 0.06-0.68, P = .009) and binary restenosis at 6 months (relative risk 0.17, 95% CI 0.05-0.60, P = .006) by multivariate analysis.

CONCLUSIONS

Dexamethasone-eluting stents exhibited an improvement in the clinical and angiographic outcomes, as compared with the control stents. These results suggest that dexamethasone may play an important role in the inhibition of the polymer-induced inflammation in the era of drug-eluting stents.

Efficacy of a dexamethasone-eluting nitinol stent on the inhibition of pseudo-intimal hyperplasia in a transjugular intrahepatic portosystemic shunt: an experimental study in a swine model

OBJECTIVE

We wanted to evaluate the feasibility and efficacy of using a dexamethasone (DM)-eluting nitinol stent to inhibit the pseudo-intimal hyperplasia following stent placement in the transjugular intrahepatic portosystemic shunt tract (TIPS) of a swine.

MATERIALS AND METHODS

Fifteen stents were constructed using 0.15 mm-thick nitinol wire; they were 60 mm in length and 10 mm in diameter. The metallic stents were then classified into three types; type 1 and 2 was coated with the mixture of 12% and 20%, respectively, of DM solution and polyurethane (PU), while type 3 was a bare stent that was used for control study. In fifteen swine, each type of stent was implanted in the TIPS tract of 5 swine, and each animal was sacrificed 2 weeks after TIPS creation. The proliferation of the pseudo-intima was evaluated both on follow-up portogram and pathologic examination.

RESULTS

One TIPS case, using the type 1 stent, and two TIPS cases, using the type 2 stent, maintained their luminal patency while the others were all occluded. On the histopathologic analysis, the mean of the maximum pseudo-intimal hyperplasia was expressed as the percentage of the stent radius that was patent, and these values were 51.2%, 50% and 76% for the type 1, 2, and 3 stents, respectively.

CONCLUSION

The DM-eluting stent showed a tendency to reduce the development of pseudo-intimal hyperplasia in the TIPS tract of a swine model with induced-portal hypertension.

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.

Dexamethasone could improve myocardial infarction outcomes and provide new therapeutic options for non-interventional patients

BACKGROUND

Statins reduce death and morbidity of acute myocardial infarction in part through immunosuppressive mechanisms, suggesting glucocorticoids could produce similar benefits. Glucocorticoids inhibit proliferation of smooth muscle cells and activation of macrophages within atherosclerotic plaques and protect ischemic myocardium through inhibition of a heat shock protein. Dexamethasone-eluting coronary stents have a decreased rate of restenosis, and oral prednisone reduces restenosis of conventional stents. Some studies from the 1970's and 1980's showed that steroids improve survival in myocardial infarction, but no conclusive large-scale randomized well-powered trials have been conducted.

PRESENTATION OF THE HYPOTHESIS

Dexamethasone administered alongside statins in the setting of acute myocardial infarction could attenuate myocardial damage in patients with diffuse disease.

TESTING THE HYPOTHESIS

Patients with acute myocardial infarction who cannot undergo angioplasty or coronary artery bypass grafting could be given a statin and intravenous and oral dexamethasone. Dexamethasone minimizes fluid retention and avoids mineralocorticoid-induced cell proliferation in plaques. Blood glucose monitoring should be ordered for all patients, but diabetic patients need not be excluded. There should be measures to prevent steroid-induced homocystinuria or more common complications such as ulcers, osteoporosis, infections and psychosis.

IMPLICATIONS OF THE HYPOTHESIS

Showing that acute coronary syndrome is a steroid-responsive disorder would have immediate relevance for patients limited to medical management because of anatomy and comorbidities, and results would similarly have application for acute ischemic stroke.

Coronary stenting and inflammation

Restenosis after stent implantation is mainly caused by neointimal proliferation through the stent struts. Experimental studies performed in the last decade indicate that inflammatory mechanisms play a key role in the process of neointimal proliferation and restenosis. Coronary stenting is a strong inflammatory stimulus, and the acute local and systemic inflammatory responses to local inflammation produced by coronary stenting are highly individual and predictive of restenosis and event-free survival. The benefit of anti-inflammatory periprocedural therapy, such as with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) and steroids, and long-term follow-up is dependent on the individual's inflammatory status. Measurement of acute-phase reactants, such as C-reactive protein plasma concentration, appears to be important for the identification of subjects at high risk and the development of specific treatment tailored to individual patients.

Inflammatory response after intervention assessed by serial C-reactive protein measurements correlates with restenosis in patients treated with coronary stenting

OBJECTIVES

We hypothesized that a higher degree of inflammatory response to coronary stenting, as measured by the change in C-reactive protein (CRP) levels after intervention in patients with stable or unstable angina, would be related to a higher risk of in-stent restenosis.

METHODS

We studied 1800 consecutive patients with stable or unstable angina treated with coronary stenting. C-reactive protein levels were serially measured before and after the intervention. The difference (Delta) between highest CRP values after intervention and CRP values before intervention was calculated. Patients were grouped into tertiles according to DeltaCRP values. The primary end point was angiographic restenosis (diameter stenosis > or = 50% at 6-month angiography). The secondary end point was clinical restenosis, defined as target vessel revascularization performed in the presence of angiographic restenosis and symptoms or signs of ischemia.

RESULTS

No relationship was found between CRP values at baseline and angiographic restenosis (P = .88). On the other hand, the change between baseline and peak postintervention CRP values strongly correlated with angiographic restenosis (30.5% in the upper tertile with DeltaCRP values >11.8 mg/L, 25.3% in the middle tertile with DeltaCRP values 3.0-11.8 mg/L, and 21.5% in the lower tertile with DeltaCRP values < 3.0 mg/L, P = .002) as well as with clinical restenosis (P = .01). Patients in the upper tertile had the highest risk of restenosis even after adjustment for other covariates.

CONCLUSIONS

The inflammatory response to coronary stenting as assessed by the change in CRP correlates with the development of in-stent restenosis. These findings provide strong support for the role of inflammation in restenosis.

Effect of dexamethasone-eluting stents on systemic inflammatory response in patients with unstable angina pectoris or recent myocardial infarction undergoing percutaneous coronary intervention

The effect of treatment with steroid-eluting stents on systemic inflammatory response was investigated in patients with unstable angina pectoris or recent myocardial infarction who underwent percutaneous intervention. Compared with controls, dexamethasone-eluting stents significantly reduced C-reactive protein peak levels 48 hours after the procedure; this effect persisted for 7 days and was particularly evident in patients with elevated (>/=3 mg/L) preprocedural C-reactive protein values. Patients receiving a dexamethasone-eluting stent had lower adverse events during follow-up.

Effects of Preinjury Administration of Corticosteroids on Pseudointimal Hyperplasia and Cytokine Response in a Rat Model of Balloon Aortic Injury

Restenosis occurs in approximately one-third of patients with coronary or peripheral vascular disease who undergo balloon angioplasty or a surgical bypass procedure primarily because of the development of pseudointimal hyperplasia (PIH). Corticosteroids were effective in suppressing PIH in several experimental studies, but no clinical studies have been reported. To resolve this discrepancy, we studied the effects of preinjury administration of several doses of methylprednisolone (MP) at targeted times in a rat model of balloon aortic injury. Rats were given either no treatment or an intravenous injection of MP (0.5, 5.0, 50, or 500 mg/kg) 2 hours before aortic injury. Four hours later interleukin-6 (IL-6), IL-10, and macrophage migration inhibitory factor (MIF) concentrations in serum and tissue of injured aortas were assessed. Two weeks after injury, damaged aortas were harvested and studied histopathologically. Compared with results in controls, MP at a dose of 5 mg/kg significantly inhibited increases in plasma and tissue levels of IL-6 and significantly reduced the pseudointimal area, pseudointimal/medial area ratio, and proliferating cell nuclear antigen index in injured vessels. Administration of MP had no significant effect on the IL-10 or MIF level. Thus in a rat model of balloon aortic injury, preinjury administration of MP 5 mg/kg mitigated the development of PIH and cell proliferation and suppressed the postinjury increase in serum and tissue IL-6 concentrations. These results suggest that there is an appropriate dosage as well as appropriate timing for MP administration to suppress PIH.

Evaluation of a high-dose dexamethasone-eluting stent

This study evaluated the safety and efficacy of a dexamethasone-eluting stent with a special high dexamethasone-loading dose for treatment of de novo coronary lesions in 30 patients. Eight patients had in-stent restenosis (restenosis rate 31%) at 6-month follow-up, and the in-stent late lumen loss was 0.96 +/- 0.63 mm due to an average intimal hyperplasia area obstruction of 32 +/- 21%, indicating that high-dose dexamethasone-loaded stents do not significantly reduce neointimal proliferation.

Lipaemia, Inflammation and Atherosclerosis

Atherosclerosis is the major cause of death in the world. Fasting and postprandial hyperlipidaemia are important risk factors for coronary heart disease (CHD). Recent developments have undoubtedly indicated that inflammation is pathophysiologically closely linked to atherogenesis and its clinical consequences. Inflammatory markers such as C-reactive protein (CRP), leucocyte count and complement component 3 (C3) have been linked to CHD and to hyperlipidaemia and several other CHD risk factors. Increases in these markers may result from activation of endothelial cells (CRP, leucocytes, C3), disturbances in adipose tissue fatty acid metabolism (CRP, C3), or from direct effects of CHD risk factors (leucocytes). It has been shown that lipoproteins, triglycerides, fatty acids and glucose can activate endothelial cells, most probably as a result of the production of reactive oxygen species. Similar mechanisms may also lead to leucocyte activation. Increases in triglycerides, fatty acids and glucose are common disturbances in the metabolic syndrome and are most prominent in the postprandial phase. People are in a postprandial state most of the day, and this phase is proatherogenic. Inhibition of the activation of leucocytes, endothelial cells, or both, is an interesting target for intervention, as activation is obligatory for adherence of leucocytes to the endothelium, thereby initiating atherogenesis. Potential interventions include the use of unsaturated long-chain fatty acids, polyphenols, antioxidants, angiotensin converting enzyme inhibitors and high-dose aspirin, which have direct anti-inflammatory and antiatherogenic effects. Furthermore, peroxisome proliferator activating receptor gamma (PPARgamma) agonists and statins have similar properties, which are in part independent of their lipid-lowering effects.

Local Delivery of Argatroban for the Prevention of Restenosis After Coronary Balloon Angioplasty-A Prospective Randomized Pilot Study-

BACKGROUND

Effective pharmacological prevention of restenosis using the systemic administration of various drugs that were effective for the prevention of restenosis in experimental studies has not been reported. The purpose of this study was to evaluate whether the local delivery of a potent thrombin inhibitor, argatroban, using a local drug delivery device would prevent restenosis after plain old balloon angioplasty (POBA).

METHODS AND RESULTS

Seventy patients with chronic coronary artery disease requiring POBA were randomly assigned to wither the control group (n=35) or the argatroban group (n=35). In the argatroban group, argatroban was administered intravenously for 30 min before the POBA and intracoronarily into the dilated site using a Dispatch catheter immediately after the POBA, followed by a postoperative intravenous infusion for 4 h. The angiographical lesion restenosis and clinical restenosis rates at follow-up were significantly lower in the argatroban group (27% and 14%) than in the control group (56% and 37%; p=0.02 and p=0.03, respectively). There was no major complication during the procedure.

CONCLUSION

The local delivery of argatroban is safe and effective in preventing restenosis after balloon angioplasty.

Therapeutic Potential of Oral Antiproliferative Agents in the Prevention of Coronary Restenosis

The treatment of coronary artery disease has reached many milestones - from balloon angioplasty to drug-eluting stents. The last decade witnessed the revolution of bare metal stents with new designs, alloys and strut thicknesses. Yet restenosis, the aphorismic 'Achilles heel', remains to be conquered. The restenosis rates with balloon angioplasty alone are 30-40% and are reduced to 20-30% with stents. Although intravascular brachytherapy proved to be a durable and safely used technique to treat in-stent restenosis, clinical event rates were not reduced to single digits.Drug-eluting stents are showing positive results in this direction, but it is too early to predict their efficacy in various subsets of lesions. With the increased usage of these stents, there are reports of problems such as late stent malapposition, subacute and late thromboses, and aneurysm formations due to the vessel toxicity associated with this method of treatment. Furthermore, when multivessel stenting is considered, the cost of drug-eluting stents is a significant problem given the fact that these are no longer 'zero restenosis' devices. There is a definite need for a simple, safe and durable solution to restenosis. Oral agents are an alternative delivery strategy that can target multiple coronary lesions, which are targets for catheter-based revascularisation with any approved metal stent and with potentially lower cost. Although oral agents have been an interesting option to treat restenosis and several agents have been tested in trials since the 1980s, the results were disappointing. The development of devices such as intravascular ultrasound has led to a greater understanding of restenosis mechanisms, and the focus on pathophysiological mechanisms, which centred mainly on platelets, growth factors and lipids, has changed to inflammation, endothelium and smooth muscle cell proliferation.Accordingly, the targets of pharmaceutical agents have shifted from platelets to cell cycle inhibition, smooth muscle cell proliferation and migration, synthesis of extra cellular matrix, and inflammatory mediators. Initial encouraging results with oral drugs such as cilostazol, sirolimus (rapamycin) and thiazolidinediones indicate a definite place for this strategy to reduce restenosis. A desirable oral agent would be anti-inflammatory, inhibit smooth muscle cell migration and proliferation, promote endothelial growth, and be well tolerated and free from significant adverse effects. It may be useful to start with a high loading dose before stent implantation and then follow with a short-term lower maintenance dose. Future trials should be aimed at finding an ideal agent, effective loading dose, maintenance dose and optimum duration of therapy.

Immunosuppressive Therapy for the Prevention of Restenosis after Coronary Artery Stent Implantation (IMPRESS Study)

OBJECTIVES

This study tested the effect of oral prednisone on clinical and angiographic restenosis rate after successful stent implantation in patients with persistent elevation of systemic markers of inflammation after the procedure.

BACKGROUND

Experimental studies have shown that corticosteroids have the potential to reduce the inflammatory response associated with stent implantation.

METHODS

Eighty-three patients undergoing successful stenting with C-reactive protein (CRP) levels >0.5 mg/dl 72 h after the procedure were randomized to receive oral prednisone or placebo for 45 days. The primary clinical end point was 12-month event-free survival rate (defined as freedom from death, from myocardial infarction, and from recurrence of symptoms requiring additional revascularization). The angiographic end points were restenosis rate and late loss at six months.

RESULTS

Twelve-month event-free survival rates were 93% and 65% in patients treated with prednisone and placebo, respectively (relative risk [RR] 0.18, 95% confidence intervals [CI], 0.05 to 0.61, p = 0.0063). Six-month restenosis rate and late loss were lower in prednisone-treated than in placebo-treated patients (7% vs. 33%, p = 0.001, and 0.39 +/- 0.6 mm vs. 0.85 +/- 0.6 mm, p = 0.001, respectively).

CONCLUSIONS

In patients with persistently high CRP levels after successful coronary artery stent implantation, oral immunosuppressive therapy with prednisone results in a striking reduction of clinical events and angiographic restenosis rate.

Rat and human aortic smooth muscle cells display differing migration and matrix metalloproteinase activities in response to dexamethasone

OBJECTIVE

The steroid dexamethasone inhibits neointimal hyperplasia development in rats but not in humans. This study investigates the differential effects of dexamethasone on rat and human smooth muscle cell migration and matrix metalloproteinase (MMP) activity.

METHODS

Rat aortic smooth muscle cells were harvested from Sprague-Dawley rats. Human aortic smooth muscle cells were obtained from Clonetics. Boyden chamber migration assays were performed with chemoattractant (platelet-derived growth factor) and varying concentrations of dexamethasone (10(-9) to 10(-5) mol/L). Zymography of culture media was used to assess MMP activity, and Western blot analysis was used for quantification of MMP-2 and tissue inhibitor of MMP-2 (TIMP-2) secretion.

RESULTS

Dexamethasone inhibits rat aortic smooth muscle cell migration in a dose-dependent fashion. An increase in concentrations of dexamethasone does not effect human aortic smooth muscle cell migration. Rat aortic smooth muscle cell MMP-2 activity is inhibited with dexamethasone in a dose-dependent fashion, and human aortic smooth muscle cell MMP-2 activity is unchanged with dexamethasone. MMP-2 secretion is inhibited with dexamethasone in rat aortic smooth muscle cells but remains unaltered in human aortic smooth muscle cells. Dexamethasone increases rat aortic smooth muscle cell TIMP-2 secretion, and human aortic smooth muscle cell TIMP-2 secretion remains constant.

CONCLUSION

Dexamethasone inhibits rat aortic smooth muscle cell migration, MMP-2 activity, and MMP-2 secretion and increases TIMP-2 secretion. These effects are not observed in human aortic smooth muscle cells. These findings may explain why dexamethasone inhibits neointimal hyperplasia in animal models but is ineffective in humans. Inhibition of human smooth muscle cell migration in vitro may be useful in predicting the effectiveness of future therapeutic agents for treatment of neointimal hyperplasia in humans.

Overview of therapies for prevention of restenosis after coronary interventions

Coronary artery disease is a leading cause of morbidity and mortality in the United States and across the world. The economic impact of coronary artery disease is staggering and on the rise. Percutaneous transluminal coronary angioplasty is widely used to treat severe, symptomatic coronary stenosis. The Achilles heel of angioplasty is restenosis of those treated arteries. As a result, numerous therapies, including mechanical and pharmacological approaches, to prevent restenosis have been studied. A greater understanding of the pathophysiology of restenosis has enhanced the success of these therapeutic approaches. To date, the most important and successful approach to limit restenosis has been the use of coronary stents. Stents have reduced the rate of restenosis from approximately 50% down to 20-30%. However, in-stent restenosis presents a new and an even more challenging dilemma. The success of adjunctive drug therapy has been promising, but, as of yet, very limited. Antithrombotic agents have reduced acute thrombosis and many of the acute complications of angioplasty. New approaches and therapies are very encouraging, and provide great hope in the treatment of restenosis. Brachytherapy has shown success in the treatment of in-stent restenosis, and recently has been approved by the United States Food and Drug Administration for this indication. Drug-eluting stents using antiproliferative drugs are the most exciting new advance in preventing restenosis, currently in Phase III trials. Gene therapy, targeted drug delivery, and newer antithrombotic agents are also under investigation. We will review the pathophysiology of restenosis, animal models, pharmacological therapies, and mechanical approaches for the treatment of restenosis.

Current approaches to therapy for vascular injury

Vascular injury is a ubiquitous phenomenon which can be both occult (such as with hyperlipidemia) and overt (such as with angioplasty). While the exact pathophysiology differs between acute and chronic atherosclerosis, both lesions can be mechanistically explained by the vasculature's exaggerated response to injury. Pharmacological attempts to treat atherosclerotic cardiovascular disease can be categorised by their role in modifying this inflammatory response. This manuscript reviews current therapy for cardiovascular injury at two levels: the chronic smouldering atheromatous lesion and intimal hyperplasia associated with acute vascular intervention. In addition, future therapeutic strategies, based within this inflammatory paradigm, are discussed.

Effect of valsartan and captopril in rabbit carotid injury. Possible involvement of bradykinin in the antiproliferative action of the renin-angiotensin blockade

The effects of the specific angiotensin II (Ang II) AT1-receptor blocker valsartan on events related to restenosis were investigated in rabbits after common carotid balloon injury. Six animals were given valsartan from two days prior to injury until 14 days post-injury. Three control groups (n=6 in each group) were either sham-operated, untreated or treated with the angiotensin-converting enzyme (ACE) inhibitor,captopril. Both ACE inhibition and AT,-receptor blockade had marked effects on plasma levels of endothelin ET1, thromboxane TXB2 and 6-keto-PGF1-alpha. The most dramatic effects on ET, levels were seen in rabbits treated with valsartan, where levels were reduced to values close to those for sham-operated animals (96.85 vs. 86.45 pg/ml). Captopril treatment led to a statistically significant (p<0.01) reduction in ET1 levels compared with untreated animals, but the reduction was only about half that seen with AT1-receptor blockade. TXB2 levels doubled (202.58 vs.413.28 pg/ml) upon arterial injury in control animals but rose by only 20-35% in rabbits treated with captopril (246.45 pg/ml) or valsartan (268.13). In untreated animals, 6-keto-PGF1-alpha levels decreased slightly after injury, but for both the captopril and valsartan groups, there were significant increases in levels of this prostaglandin derivative, effects attributed to the action of bradykinins. Levels were highest in the captopril-treated animals. Valsartan and captopril treatment led to a significant reduction in neointimal thickness and the extent of lumen stenosis compared with untreated animals. Both treatments were effective in reducing neointimal area and significantly (p<0.05)reduced cell proliferation. The differences between treatments can be attributed to the different actions of the agents, as valsartan leaves the AT2-receptor unblocked, while captopril, through inhibition of Ang II synthesis, prevents stimulation of both receptors.A combination of both treatments may be a possible way forward in the clinical prevention of restenosis.