Histopathologic comparison of human coronary in-stent and post-balloon angioplasty restenotic tissue

Impact of renin-angiotensin system inhibitors after revascularization of patients with left main coronary artery disease

BACKGROUND

There is a paucity of data regarding the effect of inhibition of the renin-angiotensin system on outcomes after percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). We sought to examine long-term outcomes of patients with left main coronary disease (LMCAD) randomized to PCI with fluoropolymer-based cobalt-chromium everolimus-eluting stents or CABG according to treatment at discharge with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) in the large-scale, multicenter, randomized EXCEL trial.

METHODS

EXCEL randomized 1905 patients with LMCAD of low and intermediate anatomical complexity (visually-assessed SYNTAX score ≤32) to PCI (n = 948) versus CABG (n = 957). Patients were categorized according to whether they were treated with ACEI/ARB at discharge; their outcomes from discharge to 5 years were examined using multivariable logistic regression with an offset for follow-up time.

RESULTS

Among 1775 patients discharged alive with known ACEI/ARB treatment status, 896 (50.5%) were treated with one of these agents. Among those treated with ACEI/ARB, the 5-year rate of all-cause death was similar after PCI or CABG (10.7% versus 9.8% respectively, adjOR, 0.94; 95% CI, 0.56-1.57) in contrast to patients not treated with ACEI/ARB (15.0% versus 7.8%, respectively, adjOR, 2.20; 95% CI, 1.32-3.67) (Pinteraction = 0.02). Significant interactions between treatment arm (PCI versus CABG) and ACEI/ARB treatment status were also found for cardiovascular death (Pinteraction = 0.03), ischemia-driven revascularization (Pinteraction = 0.03), target vessel revascularization (Pinteraction = 0.007) and target vessel failure (Pinteraction = 0.0009).

CONCLUSION

In the EXCEL trial, the postdischarge rates of death and revascularization after 5 years were similar after PCI and CABG in patients with LMCAD treated with ACEI/ARB at discharge. In contrast, event rates were higher after PCI versus CABG in those not so treated.

ACE Inhibitors Versus ARBs in Patients With NSTEMI With Preserved LV Systolic Function Who Underwent PCI With New Generation Drug-Eluting Stents

The relative superiority of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) on long-term clinical outcomes in patients with non-ST-segment elevation myocardial infarction (NSTEMI) with preserved left ventricular systolic function in the era of new generation drug-eluting stents is not well established. A total of 6436 patients with NSTEMI (ACEIs group: n = 3965 vs ARBs group: n = 2471) were enrolled. The major clinical end point was the occurrences of major adverse cardiac events (MACEs), defined as all-cause death, recurrent myocardial infarction (re-MI), and any repeat revascularization. After propensity score matching analysis, the cumulative incidences of MACEs (hazard ratio, 1.334; 95% confidence interval, 1.045-1.703; P = .021), any repeat revascularization, and target vessel revascularization (TVR) in the ARB group were significantly higher than that in the ACEI group. However, the cumulative incidences of all-cause death, cardiac death, re-MI, target lesion revascularization, and non-TVR were similar between the 2 groups. Hence, although the mortality and re-MI reduction benefits were similar between the 2 groups, the ACEIs group showed more prominent ability to decrease the occurrences of MACEs, any repeat revascularization, and TVR compared to the ARBs group in these patients during a 2-year follow-up period.

Tumor Necrosis Factor Receptor-Associated Factor 5 Promotes Arterial Neointima Formation through Smooth Muscle Cell Proliferation

Tumor necrosis factor (TNF) receptor-associated factors (TRAFs) are cytoplasmic adaptor proteins of the TNF/interleukin (IL)-1/Toll-like receptor superfamily. Ligands of this family such as TNFα, CD40L, and IL-1β promote chronic inflammatory processes such as atherosclerosis and restenosis, the latter being a common adverse reaction after vascular interventions. We previously reported overexpression of TRAF5 in murine and human atheromata and TRAF5-dependent proinflammatory functions in vitro. However, the role of TRAF5 in restenosis remains unsettled. To evaluate whether TRAF5 affects neointima formation, TRAF5-/-LDLR-/- and TRAF5+/+LDLR-/- mice consuming a high cholesterol diet (HCD) received wire-induced injury of the carotid artery. After 28 days, TRAF5-deficient mice showed a 45% decrease in neointimal area formation compared with TRAF5-compentent mice. Furthermore, neointimal vascular smooth muscle cells (vSMC) and macrophages decreased whereas collagen increased in TRAF5-deficient mice. Mechanistically, the latter expressed lower transcript levels of the matrix metalloproteinases 2 and 9, both instrumental in extracellular matrix degradation and vSMC mobilization. Additionally, TRAF5-specific siRNA interference rendered murine vSMC less proliferative upon CD40L stimulation. In accordance with these findings, fewer vSMC isolated from TRAF5-deficient aortas were in a proliferative state as assessed by Ki67 and cyclin B1 expression. In conclusion, TRAF5 deficiency mitigates neointima formation in mice, likely through a TRAF5-dependent decrease in vSMC proliferation.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

Drug- and Gene-eluting Stents for Preventing Coronary Restenosis

Coronary artery disease (CAD) has been reported to be a major cause of death worldwide. Current treatment methods include atherectomy, coronary angioplasty (as a percutaneous coronary intervention), and coronary artery bypass. Among them, the insertion of stents into the coronary artery is one of the commonly used methods for CAD, although the formation of in-stent restenosis (ISR) is a major drawback, demanding improvement in stent technology. Stents can be improved using the delivery of DNA, siRNA, and miRNA rather than anti-inflammatory/anti-thrombotic drugs. In particular, genes that could interfere with the development of plaque around infected regions are conjugated on the stent surface to inhibit neointimal formation. Despite their potential benefits, it is necessary to explore the various properties of gene-eluting stents. Furthermore, multifunctional electronic stents that can be used as a biosensor and deliver drug- or gene-based on physiological condition will be a very promising way to the successful treatment of ISR. In this review, we have discussed the molecular mechanism of restenosis, the use of drug- and gene-eluting stents, and the possible roles that these stents have in the prevention and treatment of coronary restenosis. Further, we have explained how multifunctional electronic stents could be used as a biosensor and deliver drugs based on physiological conditions.

Oral Mycophenolate Mofetil Prevents In-Stent Intimal Hyperplasia Without Edge Effect

Neointimal hyperplasia is in the forefront in in-stent restenosis. Prevention of in-stent restenosis is possible by reducing and inhibiting the hyperplasia of smooth muscle cells. The authors planned this study to test the hypothesis that when administered orally, mycophenolate mofetil (MMF) could inhibit in-stent neointimal hyperplasia. The study included 14 New Zealand rabbits. The rabbits were allocated to 2 different groups: Group 1 included 7 rabbits that were given MMF, 40 mg/kg/day by oral route. Group 2 included 7 rabbits that were not given MMF after the stenting. Sampling materials were taken before and after stenting by incising the artery so as to cover a 5-mm area. The samples taken from the edge of the stent in Group 1 showed focal neointimal cell proliferation, but it was less than that from the control group. Neointimal thickness was 0.048 ±0.009 mm and neointimal area was 0.0925 ±0.019 mm2. Apparent neointimal cell proliferation and thickening of the intimal layer were observed in Group 2. Neointimal thickness at the stent edge was 0.147 ±0.051 mm and the neointimal area was 0.154 ±0.023 mm2. The differences between groups in terms of neointimal thickness and neointimal area were statistically significant (p=0.001 for thickness and p=0.001 for area). In-stent artery samples of Group 1 showed that some subjects had no neointimal cell proliferation, while others had very limited focal intimal thickening. Neointimal thickening was 0.071 ±0.003 mm and neointimal area was 0.073 ±0.003 mm2. In Group 2 apparent, and mostly focal, neointimal cell proliferation and formation of intimal layer were observed in the stent. Neointimal thickening was 0.154 ±0.069 mm and neointimal area was 0.279 ±0.059 mm2. The comparison between groups showed significant differences (p=0.011 for thickness and p=0.001 for area). It was established in the third month that endothelialization was completed in both groups. Oral MMF decreased in-stent intimal hyperplasia without edge effect. It was concluded that for the prevention of in-stent restenosis, studies should be conducted for using systemic immunosuppressive treatments in humans as well.

Current Role of Laser Angioplasty of Restenotic Coronary Stents

Treatment of in-stent restenosis (ISR) with conventional percutaneous transluminal coronary angioplasty (PTCA) causes significant recurrent neointimal tissue growth in 30-85%. Therefore, laser ablation of intrastent neointimal hyperplasia before balloon dilation can be an attractive alternative. However, the long-term outcomes of such treatment have not been studied thoroughly enough. This prospective case-control study evaluated angiographic and clinical outcomes of PTCA alone and a combination of excimer laser coronary angioplasty (ELCA) and adjunct PTCA in 125 patients with ISR. ELCA was performed before balloon dilation in 67 patients, PTCA alone was performed in 58 patients. Basic demographic and clinical data were comparable in both groups. Lesions included in ELCA group were longer (17.1 ±9.9 vs 13.6 ±9.1 mm; p=0.034), more complex (36.5% type C stenoses vs 14.3%; p=0.006), and more frequently had reduced distal blood flow (TIMI <3: 18.9% vs 4.8%; p=0.025) compared to lesions in the PTCA group. Immediate angiographic results of PTCA and ELCA + PTCA appeared to be comparable. PTCA alone was successful in 57 patients (98.3%), ELCA + PTCA, in 66 patients (98.5%). The rates of hospital complications were comparable (3.0% in ELCA group vs 8.6% in PTCA group). The 1-year follow-up showed that the rates of major adverse cardiac events (MACE) were comparable in the 2 groups (37.3% in ELCA group vs 46.6% in PTCA group). The rates of target vessel revascularization (TVR) within 1 year after the intervention were also similar in the 2 groups (32.8% vs 34.5%). The data mean that ELCA in patients with complex ISR is efficient and safe. Despite a higher complexity of lesions in the ELCA group, no increase in the rate of complications was registered.

Novel Respiratory Syncytial Virus-Like Particle Vaccine Composed of the Postfusion and Prefusion Conformations of the F Glycoprotein

Respiratory syncytial virus (RSV) is the leading cause of severe respiratory disease in infants and children and represents an important global health burden for the elderly and the immunocompromised. Despite decades of research efforts, no licensed vaccine for RSV is available. We have developed virus-like particle (VLP)-based RSV vaccines assembled with the human metapneumovirus (hMPV) matrix protein (M) as the structural scaffold and the RSV fusion glycoprotein (F) in either the postfusion or prefusion conformation as its prime surface immunogen. Vaccines were composed of postfusion F, prefusion F, or a combination of the two conformations and formulated with a squalene-based oil emulsion as adjuvant. Immunization with these VLP vaccines afforded full protection against RSV infection and prevented detectable viral replication in the mouse lung after challenge. Analyses of lung cytokines and chemokines showed that VLP vaccination mostly induced the production of gamma interferon (IFN-γ), a marker of the Th1-mediated immune response, which is predominantly required for viral protection. Conversely, immunization with a formalin-inactivated RSV (FI-RSV) vaccine induced high levels of inflammatory chemokines and cytokines of the Th2- and Th17-mediated types of immune responses, as well as severe lung inflammation and histopathology. The VLP vaccines showed restricted production of these immune mediators and did not induce severe bronchiolitis or perivascular infiltration as seen with the FI-RSV vaccine. Remarkably, analysis of the serum from immunized mice showed that the VLP vaccine formulated using a combination of postfusion and prefusion F elicited the highest level of neutralizing antibody and enhanced the Th1-mediated immune response.

The evolution of coronary stents: a brief review

Percutaneous coronary intervention is the most prevalent method for coronary artery revascularization. Initial interventions using balloon angioplasty had limited efficacy because coronary dissections, arterial recoil, and neointimal formation led to high rates of abrupt vessel closure and clinical restenosis. With the introduction of coronary stents, vascular dissections were stabilized and arterial recoil was eliminated, but neointimal accumulation remained problematic, resulting in the development of in-stent restenosis (ISR) in 20%-30% of cases. Drug-eluting stents (DESs) were developed to release antiproliferative agents at the site of arterial injury to attenuate neointimal formation. Although DESs have incrementally improved outcomes after percutaneous coronary intervention, delayed re-endothelialization and stent thrombosis remain important challenges. Herein we review the pathophysiology of ISR, stent thrombosis, and briefly summarize the clinical evidence behind first- and second-generation DESs. Moreover, we discuss advancements in our understanding of the pathogenesis of ISR and potential novel therapeutic strategies to improve clinical outcomes.

Do statins have a role in reduction/prevention of post-PCI restenosis?

The pathophysiology of post-PCI restenosis involves neointimal formation that consists of three phases: thrombosis (within 24 h), recruitment (3-8 days), and proliferation, which starts on day 8 of PCI. Various factors suggested to be predictors/risks for restenosis include C-reactive protein (CRP), inflammatory mediators (cytokines and adhesion molecules), oxygen radicals, advanced glycation end products (AGEs) and their receptors (RAGE), and soluble RAGE (sRAGE). The earlier noted factors produce thrombogenesis, vascular smooth muscle cell proliferation, and extracellular matrix formation. Statins have pleiotropic effects. Besides lowering serum cholesterol, they have various other biological effects including antiinflammatory, antithrombotic, CRP-lowering, antioxidant, antimitotic, and inhibition of smooth muscle cell proliferation. They inhibit matrix metalloproteinase and cyclooxygenase-2, lower AGEs, decrease expression of RAGE and increase levels of serum sRAGE. They also increase the synthesis of nitric oxide (NO) by increasing endothelial NO synthase expression and activity. Preprocedural statin therapy is known to reduce peri- and post-PCI myonecrosis and reduce the need for repeat revascularization. There is evidence that statin-eluting stents inhibit in-stent restenosis in animal models. It is concluded that because of the above attributes of statins, they are suitable candidates for reduction of post-PCI restenosis and post-PCI myonecrosis. The future directions for the use of statins in reduction of post-PCI restenosis and myonecrosis have been discussed.

Directional coronary atherectomy: a time for reflection. Should we let it go?

A series of interventional tools have emerged since the advent of percutaneous coronary angioplasty. Several are fundamental and used routinely, while others less favourable have fallen short of mainstream therapy and/or have settled as a niche device. We present an overview of the evolution of directional coronary atherectomy (DCA), a unique device that was originally conceived in 1984 to solve the limitations of balloon angioplasty. Unfortunately, we have witnessed its use fall significantly out of favour due to premature and controversial study results. In many interventional laboratories DCA is no longer available. However, we strongly feel that allowing DCA to join the list of extinct interventional tools would be very unfortunate. We, herein, present a series of complex percutaneous coronary procedures to illustrate the convenience of DCA use as a lesion-specific niche device. Finally, DCA offers a valuable distinct clinical research function as it allows for in vivo pathological coronary tissue examination. In conclusion, we plead for its continued production and use as an interventional niche device for the wellbeing of our patients.

Impact of small thrombus formation in restenotic bare-metal stent lesions associated with acute coronary syndrome: identification by optical coherence tomography

BACKGROUND

Although in-stent restenosis (ISR) after bare-metal stent (BMS) implantation is considered to be clinically benign, ISR is often associated with adverse complications, such as acute coronary syndrome (ACS). The frequency, type, and location of thrombi in ISR lesions and their clinical presentation have not yet been precisely validated.

METHODS

Thirty angiographic ISR lesions occurring within 3 to 8 months after stenting were evaluated by optical coherence tomography (OCT). A thrombus was defined as a mass protruding into the lumen with an irregular surface, and its type was divided into red or white. The maximum size of a thrombus and the longitudinal distance from the thrombus to the narrowest lumen were measured.

RESULTS

A thrombus was identified in 2 patients by angiography and in 10 patients by OCT (7% vs. 33%; P=0.01). OCT showed that 9 patients had white thrombus and another patient had both types of thrombi. ACS relevant to ISR was seen in 6 patients, and the frequency of ACS was significantly higher in patients with thrombus than in those without thrombus [50% (5/10) vs. 5% (1/20); P=0.003]. The maximum size of the thrombus was 412 ± 220 µm in height, 424 ± 251 µm in width, and the longitudinal distance between the thrombus and the minimum lumen area was 0.3 ± 0.7 mm.

CONCLUSIONS

One third of ISR lesions following BMS deployment dominantly contained a white thrombus, and half of them were associated with ACS. A small thrombus formation adjacent to the narrowest lumen in an ISR lesion may therefore contribute to the clinical presentation of ACS.

The clinical presentation of restenosis after bare metal stent implantation: behind a facade of benignity

Contrary to common belief, bare metal in-stent restenosis (ISR) seems to be not a benign clinical entity. Thus,we believed that continued efforts are warranted to prevent bare metal ISR, including aggressive use of drug-eluting stent (DES) to decrease the incidence of acute coronary syndromes. However, despite improved outcomes with DES, bare metal stent (BMS) will continue to play a role for both clinical and economic reasons and we feel that there is still a future for BMS.

Atherosclerosis and vascular injury: the effect of a perivascular nitric oxide donor in a cholesterol-fed rabbit model

Nitric oxide (NO) has been shown to prevent neointimal hyperplasia and decrease atherosclerosis in several animal models. It is a major modulator of vascular homeostasis and has vasoprotective effects against atherosclerosis. However, NO-based therapies with such purposes have not been used in the clinical arena. Our objective was to combine a medical grade elastomer and an NO donor, diethylenetriamine NO adduct (DETA/NO), to determine whether its perivascular administration can attenuate atherosclerosis and vascular injury. Aortic intimal injury was produced using paediatric pulmonary valvoplasty catheter in 22 healthy male New Zealand White rabbits, which were fed a high-cholesterol diet for 4 weeks beforehand. A mixture of the elastomer Silastic and DETA/NO was applied locally to cover the aortas in the experiment group. After 6 additional weeks on the high-cholesterol diet, the aortas and blood samples were harvested for pathologic analysis and comparison with the control group. Mean atherosclerosis and vascular injury surface area was 6.68 x 10(5) microm2 in the experiment group, compared with 3.44 x 10(5) microm2 in the controls. However, there was no statistically significant difference in atherosclerotic surface area between the two groups. Perivascular application of the NO donor DETA/NO, in the concentration we used, did not prevent atherosclerosis in high cholesterol-fed rabbits. This finding prompts more careful assessment before possible clinical uses.

Late occlusive in-stent restenosis of a bare-metal stent presenting with ST-elevation anterior MI: is restenosis better than a late stent thrombosis?

In-stent restenosis (ISR) occurs in 20% to 40% of de novo coronary lesions treated with bare-metal stents (BMS), depending on lesion and patient-related factors. Drug-eluting stents coated with antiproliferative agents, represent a valid rationale for treatment and prevention of recurrent ISR, with low MACE rates. However, case reports and observational studies reported a definite increase in the incidence of late stent thrombosis after drug-eluting stents use, particularly in off-label cases and after clopidogrel withdrawal. The case we present shows target vessel occlusion occurring at the site of a previously implanted BMS, suggesting that in-stent restenosis was the main pathological mechanism leading to abrupt thrombotic vessel closure and acute myocardial infarction.

Midkine is expressed by infiltrating macrophages in in-stent restenosis in hypercholesterolemic rabbits

BACKGROUND

Neointimal hyperplasia is strikingly suppressed in an endothelium injury model in mice deficient in the growth factor midkine. Knockdown of midkine expression by means of antisense oligonucleotide or small interfering RNA has been shown to lead to suppression of neointimal hyperplasia in a balloon injury model and a rabbit vein graft model; therefore, midkine is an essential factor for neointimal hyperplasia. These findings, however, do not necessarily apply to the function of midkine in vascular stenoses such as in-stent restenosis, because human vascular stenosis is often accompanied by atherosclerosis.

METHODS

We investigated midkine expression in the neointima induced by implantation of a bare metal stent in the atheromatous lesions of hypercholesterolemic rabbits. We analyzed midkine expression during a THP-1 cell differentiation and in peritoneal macrophages exposed to low-density lipoprotein or oxidized low-density lipoprotein.

RESULTS

Midkine expression reached the maximum level within 7 days after stenting and was detected in infiltrating macrophages. Differentiation of THP-1 cells to macrophage-like cells did not trigger midkine expression. Neither low-density lipoprotein nor oxidized low-density lipoprotein enhanced midkine expression in peritoneal macrophages that had been activated by thioglycollate, although these cells expressed a significant amount of midkine.

CONCLUSION

The results indicate that macrophages are the major source of midkine in the atherosclerotic neointima. The amount of midkine expressed in macrophages may be sufficient (ie, further enhancement of the expression is not necessary) for the pathogenesis, because oxidized low-density lipoprotein stimulation did not induce the midkine expression.

CLINICAL RELEVANCE

The growth factor midkine is induced during vascular stenosis in mouse and rat models with normal diet. Knockdown of midkine expression suppresses neointimal hyperplasia. The vascular response after stenting differs from that after balloon injury in that the inflammation is more prolonged and the accumulation of macrophages is more abundant in stent-injured vessel. We found here that macrophages are the major source of midkine in the atherosclerotic neointima of in-stent restenosis in hypercholesterolemic rabbits. Our data suggest that midkine has an important role in in-stent restenosis of atherosclerotic vessels and is a candidate molecular target to prevent in-stent restenosis.

Intimal hyperplasia in murine models

The most commonly used procedures to induce arterial injury in mice are carotid artery ligation with cessation of blood flow and mechanically-induced denudation of endothelium in the carotid or the femoral arteries. Both procedures result in neointimal hyperplasia after two to three weeks. A survey of various inbred strains of mice shows that strain-specific differences in susceptibility to injury-induced neointimal hyperplasia are different than those for susceptibility to diet-induced atherosclerosis, with strains identified as susceptible to both neointimal hyperplasia and atherosclerosis, resistant to both, susceptible to atherosclerosis but resistant to neointimal hyperplasia, or resistant to atherosclerosis but susceptible to neointimal hyperplasia. Inflammatory cells such as T and B lymphocytes, which are contributory to atherosclerosis, are protective against injury-induced neointimal hyperplasia. In contrast, the infiltration of monocytes into the site of injury and their differentiation to macrophages favor neointimal hyperplasia similar to their pathogenic role in atherosclerosis. The regulatory role of lymphocytes and macrophages in neointimal hyperplasia is related to the production of cytokines such as interferon-gamma and tumor necrosis factor-alpha, respectively. Interestingly, inducible nitric oxide synthase (iNOS) activity appears to inhibit neointimal hyperplasia in the endothelial denudation model but contributes to neointimal hyperplasia when arterial injury is induced by periadventitial cuff placement. The difference appears to be due to the time required for endothelial recovery and the participation of inflammatory cells. Thus, although arterial injury-induced neointimal hyperplasia results in similar vascular occlusion as progressive atherosclerosis, the pathology and mechanism of the two disease processes are quite different.

Pro-healing drug-eluting stents: a role for antioxidants?

Current strategies to lower the incidence of ISR (in-stent restenosis) following PCI (percutaneous coronary intervention) are aimed at modifying arterial healing after stent injury. This can impair endothelial recovery and render the vessel prone to acute thrombosis. As early restoration of endothelial integrity inhibits neointimal growth and thrombosis, alternative approaches which encourage this process may provide a more effective long-term result after PCI. Oxidative stress is enhanced after PCI and participates in the regulation of endothelial regeneration and neointimal growth. Moreover, evidence suggests antioxidants improve re-endothelialization and inhibit ISR. By promoting, rather than blocking, the healing process, antioxidant and other therapies may offer an alternative or additional approach over the antiproliferative approaches common to many current devices.

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.

Clinical in-stent restenosis with bare metal stents: is it truly a benign phenomenon?

OBJECTIVE

In-stent restenosis (ISR) remains an important problem following percutaneous coronary intervention (PCI). Although it is generally believed that patients with ISR present with stable angina, this has not been well characterized. The aim of this study was to define the incidence, predictors, timing and clinical presentation of patients with ISR requiring repeat catheterization.

DESIGN

Using a multiregion prospective database which captures all patients undergoing cardiac catheterization and revascularization in the Province of Alberta, Canada, consecutive bare metal stent (BMS) implantations from January 1, 1998 to December 31, 2002 were analyzed. All patients with a repeat angiogram within one year of the index PCI were reviewed for evidence of clinical-ISR (CISR), defined as ISR as the cause for clinical presentation at angiography.

RESULTS

Of the 12,492 consecutive PCI patients reviewed, 2521 had repeat angiography and 744 patients (6.0%) had CISR by study definition. The mean time to repeat angiography in CISR patients was 5.4+/-2.7 months and multivariate analysis identified female gender, diabetes mellitus, and prior PCI as predictors. The majority of patients presented with an acute coronary syndrome: 52.2% unstable angina/non-ST elevation myocardial infarction and 18.5% ST elevation myocardial infarction. Only 25.3% presented with stable exertional angina.

CONCLUSION

Although the incidence of CISR within one year after BMS was relatively low, the recurrent clinical event in the majority of cases was a high-risk coronary syndrome. Thus, careful consideration of the risks of ISR to a specific patient against the cost implications of novel and expensive means to decrease its occurrence is required.

Midterm outcomes of paclitaxel-eluting stents for the treatment of intracranial posterior circulation stenoses

OBJECT

Symptomatic intracranial vertebral and basilar artery atherosclerotic stenoses carry a high risk of stroke and permanent disability if refractory to maximal medical therapy. The authors conducted a study to determine the technical feasibility and midterm clinical and angiographic outcomes in patients in whom paclitaxel-eluting stents were placed for the treatment of symptomatic intracranial posterior circulation stenoses.

METHODS

A retrospective review of medical records and imaging studies was performed for 13 consecutive patients in whom paclitaxel-coated stents were used to treat symptomatic posterior circulation intracranial stenoses between 2002 and 2005. Clinical follow-up data were supplemented by telephone interviews. The technical success rate for stent placement was 100%. One patient (8%) suffered a periprocedural stroke. Twelve patients (92%) underwent clinical follow up for a minimum of 3 months postsurgery, and 11 (92%) of these patients remained asymptomatic after a mean period of 10.9 months. Nine patients (69%) underwent catheter angiographic follow up, and no patient had significant in-stent recurrence of stenosis after a mean period of 5.4 months.

CONCLUSIONS

Treatment of intracranial posterior circulation stenoses with drug-eluting stents is technically feasible, and the rate of clinically significant periprocedural complications is low. Rates of stenosis recurrence are reduced compared with those of bare-metal stents in the midterm. Midterm clinical outcome is excellent; no symptom recurrence was observed in this patient cohort.

Meta-analysis comparing the effect of drug-eluting versus bare metal stents on risk of acute myocardial infarction during follow-up

The only clinical benefit of drug-eluting stents (DESs) over bare metal stents (BMSs) is a significant decrease in the need for new revascularization procedures. We evaluated whether DESs also decrease the incidence of myocardial infarction at midterm. We performed a meta-analysis from 25 randomized trials comparing commercially available DESs with BMSs that included 9,791 patients overall. There was no heterogeneity across the trials included (Q test for heterogeneity, p = 0.68). Of the 9,791 patients included in all the trials, 364 developed an acute myocardial infarction during follow-up (6 to 12 months). The risk of myocardial infarction was significantly lower in patients allocated to DESs (3.3% vs 4.2% in those allocated to BMSs, odds ratio 0.79, 95% confidence interval 0.64 to 0.97, p = 0.03). In conclusion, the significant decrease in angiographic restenosis associated with the use of DESs leads not only to a decreased need for subsequent revascularization procedures but also a decreased incidence of myocardial infarction during the first 12 months after stent implantation.

A meta-analysis of randomized controlled trials of intracoronary gamma- and beta-radiation therapy for in-stent restenosis

We assessed the effectiveness of intracoronary brachytherapy and compared treatment effects for the two radiation sources as well as the performance of the procedure in saphenous vein grafts (SVG) and native coronary arteries. Five randomized controlled trials comparing intracoronary brachytherapy with placebo involving a total of 1310 patients were reviewed for a meta-analysis. Risk differences (RD) for major adverse cardiac events (MACE), target vessel revascularization, target lesion revascularization, and angiographic binary restenosis at 6-12 months were computed, and a meta-regression analysis of MACE was performed. For MACE, the RD was 0.19 (95% confidence interval [CI], 0.09%-0.29%; P value, 0.00); there was significant between-study variance of 0.2395. In univariate meta-regression analyses, diabetes was a significant factor for the between-study variance (P value, 0.000). In multivariate meta-regression analyses adjusted for diabetes and lesion length, neither gamma-radiation source nor SVG was a significant factor for the between-study variance (P value, 0.675 and 0.433, respectively); the adjusted between-study variance was 0.000. Intra-coronary brachytherapy is effective compared with placebo at mid-term follow up. Neither procedure in SVG (gamma radiation) nor difference in radiation source (beta or gamma) in native coronary arteries was a significant factor in brachytherapy effectiveness compared to placebo.

Acute coronary syndrome may occur with in-stent restenosis and is associated with adverse outcomes (the PRESTO trial)

Patients with de novo acute coronary syndromes (ACSs) have a higher rate of adverse cardiac events and recurrent revascularization after percutaneous coronary interventions compared with patients who have stable angina. However, it is not known if an ACS presentation in patients with in-stent restenosis (ISR) is associated with a worse prognosis. Using the large PRESTO database of patients with ISR, we compared outcomes after successful percutaneous coronary intervention in 824 patients who presented with ACS with 617 patients who had stable angina. In-hospital and 9-month follow-up for myocardial infarction, target vessel revascularization, death, and a combined outcome of major adverse cardiac events (MACEs) were obtained. Follow-up angiographic results were also compared in those patients included in the angiographic substudy (140 patients with ACS and 99 with stable angina). Patients with ISR who presented with ACS were older and less often men, with higher incidences of diabetes, hypertension, tobacco use, previous coronary artery bypass graft surgery, and congestive heart failure. In-hospital complications were rare and similar in the 2 groups. At follow-up, patients with ACS had higher incidences of target vessel revascularization (33% vs 21%, p <0.001), MACEs (35% vs 22%, p <0.001), and angiographic restenosis (> or =50% narrowing, 56% vs 42%, p = 0.043). In multivariate analysis, after adjusting for baseline differences, an ACS presentation was associated with a higher incidence of long-term MACEs (odds ratio 1.66, 95% confidence interval 1.27 to 2.18, p <0.001). In conclusion, an ACS presentation in patients with ISR is associated with a higher incidence of recurrent adverse cardiovascular events and angiographic restenosis.

Therapeutic Potentials of Sarpogrelate in Cardiovascular Disease*

In view of the pivotal role of serotonin (5-HT) in a wide variety of cardiovascular disorders, extensive effort has been made to develop different types of 5-HT receptor antagonists for therapeutic use. On the basis of experimental studies, this article is focused on the potentials of sarpogrelate, a specific 5-HT2A receptor antagonist as an antiplatelet, antithrombotic, antiatherosclerotic and antianginal agent. The major effects of sarpogrelate are due to the inhibition of 5-HT-induced platelet aggregation and smooth muscle cell proliferation. This agent was found to attenuate the 5-HT-mediated increase in intracellular Ca2+ and ischemia-reperfusion injury in the heart. Sarpogrelate has been found to have beneficial effects in peripheral vascular disease, restenosis after coronary stenting, pulmonary hypertension, acute and chronic myocardial infarction.

Myocardial Infarction as a Presentation of Clinical In-Stent Restenosis

BACKGROUND

In-stent restenosis is considered to be a gradual and progressive condition and there is scant data on myocardial infarction (MI) as a clinical presentation.

METHODS AND RESULTS

Of 2,462 consecutive patients who underwent percutaneous coronary intervention between June 2001 and December 2002, clinical in-stent restenosis occurred in 212 (8.6%), who were classified into 3 groups: ST elevation MI (STEMI), non-ST elevation MI (NSTEMI) and non-MI. Of the 212 patients presenting with clinical in-stent restenosis, 22 (10.4%) had MI (creatine kinase (CK)>or=2xbaseline with elevated CKMB). The remaining 190 (89.6%) patients had stable angina or evidence of ischemia by stress test without elevation of cardiac enzymes. Median interval between previous intervention and presentation for clinical in-stent restenosis was shorter for patients with MI than for non-MI patients (STEMI, 90 days; NSTEMI, 79 days; non-MI, 125 days; p=0.07). Diffuse in-stent restenosis was more frequent in MI patients than in non-MI patients (72.7% vs 56.3%; p<0.005). Renal failure was more prevalent in patients with MI than in those without MI (31.8% vs 6.3%, p=0.001). Compared with the non-MI group, patients with MI were more likely to have acute coronary syndromes at the time of index procedure (81.8% vs 56.8%, p=0.02).

CONCLUSION

Clinical in-stent restenosis can frequently present as MI and such patients are more likely to have an aggressive angiographic pattern of restenosis. Renal failure and acute coronary syndromes at the initial procedure are associated with MI.

Pre-procedural ACE-activity does not predict symptomatic in-stent restenosis

BACKGROUND

Several studies indicate that ACE-activity is related to atherosclerosis. We investigated the correlation between ACE-activity, in plasma as well as in the atherosclerotic plaque, and in-stent restenosis.

METHODS AND RESULTS

ACE-activity was measured in blood samples from 178 patients who underwent a percutaneous coronary intervention with stent placement. During 8 months follow-up, 51 of these patients had an adverse clinical event. ACE-activity did not differ between patients with or without adverse events (21.5 vs. 23.1 nM/ml/min; P=0.36). Tissue samples were obtained with an atherectomy catheter before elective stent placement in another group of 13 patients with de novo stenosis. In this tissue, we determined the ACE-content immunohistologically. These patients were scheduled for follow-up quantitative coronary angiography after 12 months. In this group, the quantity of ACE was not correlated to the late luminal loss (0.31 vs. 0.38 mm; P=0.76).

CONCLUSION

In this study, pre-procedural ACE-activity, in plasma as well as in the atherosclerotic plaque, does not predict the occurrence of in-stent restenosis.

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.

Renin-Angiotensin System Intervention to Prevent In-Stent Restenosis

The occurrence of in-stent restenosis is a major drawback of percutaneous transluminal coronary angioplasty with stent placement. Target vessel revascularization is necessary in 15% of patients who receive a stent. Recent advances in the development of drug-eluting stents have reduced these numbers tremendously. However refinement of antirestenotic therapies remains obligatory. The emerging interest in more physiological antirestenotic therapies might unchain an interest in the well-known inhibitors of the rennin-angiotensin system (RAS), the angiotensin-converting enzyme inhibitors, and the angiotensin II type I receptor blockers. Contradictory results overshadow the discussion of whether intervention in the RAS could prevent in-stent restenosis. This review discusses the pathophysiology of in-stent restenosis, the role of the RAS in in-stent restenosis, and the possible role of RAS intervention in the prevention of in-stent restenosis.

Pathogen burden, inflammation, proliferation and apoptosis in human in-stent restenosis. Tissue characteristics compared to primary atherosclerosis

Pathogenic events leading to in-stent restenosis (ISR) are still incompletely understood. Among others, inflammation, immune reactions, deregulated cell death and growth have been suggested. Therefore, atherectomy probes from 21 patients with symptomatic ISR were analyzed by immunohistochemistry for pathogen burden and compared to primary target lesions from 20 stable angina patients. While cytomegalovirus, herpes simplex virus, Epstein-Barr virus and Helicobacter pylori were not found in ISR, acute and/or persistent chlamydial infection were present in 6/21 of these lesions (29%). Expression of human heat shock protein 60 was found in 8/21 of probes (38%). Indicated by distinct signals of CD68, CD40 and CRP, inflammation was present in 5/21 (24%), 3/21 (14%) and 2/21 (10%) of ISR cases. Cell density of ISR was significantly higher than that of primary lesions (977 +/- 315 vs. 431 +/- 148 cells/mm(2); p < 0.001). There was no replicating cell as shown by Ki67 or PCNA. TUNEL(+) cells indicating apoptosis were seen in 6/21 of ISR specimens (29%). Quantitative analysis revealed lower expression levels for each intimal determinant in ISR compared to primary atheroma (all p < 0.05). In summary, human ISR at the time of clinical presentation is characterized by low frequency of pathogen burden and inflammation, but pronounced hypercellularity, low apoptosis and absence of proliferation.

The effect of long-term clopidogrel use on neointimal formation after percutaneous coronary intervention

OBJECTIVE

The purpose of this study was to evaluate the long term effect of clopidogrel-based antiplatelet therapy on neointimal formation.

METHODS

This study comprised 78 patients with typical stable angina pectoris or documented myocardial ischaemia, and with only one angiographic lesion in one native coronary artery undergoing successful stent implantation without predilatation with C-reactive protein levels < or =5 mg/l at 72 h after the procedure. All patients received dual antiplatelet therapy with 75 mg/day clopidogrel and 300 mg/day aspirin for four weeks. Clopidogrel was switched to isochronous placebo in half of the patients (n=39) at the end of the fourth week. This allocation was maintained for 20 weeks, and at week 24 of the study, coronary angiography and intravascular ultrasound imaging were performed again in all cases in order to evaluate the changes that had occurred in the in-stent neointimal formation; rates of restenosis were also recorded

RESULTS

At the end of the follow-up period, angiographic stenosis diameter and restenosis rates were smaller in the clopidogrel group than in the placebo group (23.3% versus 35.6%, p=0.05 and 5.12% versus 10.25%; p=0.03 respectively); the intravascular ultrasonographic neointimal cross sectional area was also smaller in the clopidogrel group (3.6 +/- 2.7 mm(2) versus 5.2 +/- 2.5 mm(2), p=0.03).

CONCLUSIONS

Long-term clopidogrel administration significantly reduced neointimal formation at the stent site as well as reducing major clinical events in patients who did not develop high-risk systemic inflammatory response after percutaneous coronary intervention.

Promoter polymorphism in the CD14 gene and concentration of soluble CD14 in patients with in-stent restenosis after elective coronary stenting

BACKGROUND

Activated monocytes/macrophages, neutrophils, endothelial cells and smooth muscle cells participate in the restenosis processes. Monocytes/macrophages and neutrophils are activated by lipopolysaccharide (LPS) via CD14. Endothelial cells and smooth muscle cells are also stimulated by soluble CD14 (sCD14)-LPS complexes.

METHODS

We tested the hypothesis that C(-260)-->T polymorphism of the CD14 gene and sCD14 might be predictors for in-stent restenosis. We analyzed 129 consecutive patients who underwent elective coronary stenting. The restenosis was defined as > or =50% diameter stenosis at follow-up angiography.

RESULTS

The prevalence of the T/T genotype and the concentration of sCD14 were significantly higher in the restenosis group than in the no-restenosis group. This CD14 polymorphism also affected the levels of sCD14, therefore, we divided the patients into four groups. The loss index was 24.8% in C/C or C/T and < or =50th percentile of sCD14, 35.9% in T/T and < or =50th percentile of sCD14, 44.2% in C/C or C/T and >50th percentile of sCD14, and 49.1% in T/T and >50th percentile of sCD14 (P=0.02). The restenosis rate was 10.0%, 26.7%, 26.2% and 50.0% in each group, respectively (P=0.003). In the multivariate analysis, T/T and >50th percentile of sCD14 was the independent predictor for in-stent restenosis.

CONCLUSIONS

This study showed that the T/T genotype with a high level of sCD14 is an independent predictor of in-stent restenosis. The activation of monocytes/macrophages, endothelial cells and smooth muscle cells mediated by CD14 and/or sCD14 may play an important role in the restenosis processes.

Treatment of In-Stent restenosis using a stent with non-polymer-based paclitaxel elution

Treatment of in-stent restenosis remains a therapeutic challenge. Twenty-seven lesions with in-stent restenosis were treated with non-polymer-based paclitaxel-eluting stents. At 6-month follow-up, in-stent late loss was 0.44 +/- 0.54 mm and the restenosis rate was 20%, indicating effective treatment for reduction of recurrent restenosis.

Coronary in-stent restenosis following beta brachytherapy A histopathological examination

Two cases of in-stent restenosis of a coronary artery bypass vein graft following beta (beta) brachytheraphy are presented. Previously unreported histopathology of directed atherectomy specimens of such restenotic lesions and a discussion of their proposed significance form the basis of this report.

Catheter based intracoronary brachytherapy leads to increased platelet activation

BACKGROUND

Vascular brachytherapy (VBT) after percutaneous coronary intervention (PCI) is associated with a higher risk of stent thrombosis than conventional treatment.

OBJECTIVE

To investigate in vivo periprocedural platelet activation with and without VBT, and to assess a possible direct effect of radiation on platelet activation.

DESIGN

Of 50 patients with stable angina, 23 received VBT after PCI, while 27 had PCI only. The 23 patients who received VBT after PCI were pretreated for one month with aspirin and clopidogrel. Platelet activation was assessed by flow cytometry.

RESULTS

The two patient groups did not differ in their platelet activation before the intervention. There was a significant increase in activation immediately after VBT, with 21.2% (interquartile range 13.0% to 37.6%) thrombospondin positive and 54.0% (42.3% to 63.6%) CD 63 positive platelets compared with 12.7% (9.8% to 14.9%) thrombospondin positive and 37.9% (33.2% to 45.2%) CD 63 positive platelets before the intervention (p < 0.001 and p < 0.01, respectively). Patients without VBT had no periprocedural difference in platelet activation immediately after PCI. No increase in platelet activation was found after ex vivo irradiation of blood samples obtained from healthy controls.

CONCLUSIONS

Catheter based intracoronary VBT carried out according to current standards is highly thrombogenic. The current antithrombotic treatment with aspirin and clopidogrel is not sufficient to suppress platelet activation during the procedure. From in vitro experiments, it appears that platelet activation during brachytherapy is not caused by irradiation but by the procedure of catheter based VBT.

Histological findings after angioplasty using conventional balloon, radiofrequency thermal balloon, and stent for experimental aortic coarctation

BACKGROUND

Use of balloon angioplasty or stent implantation has been reported to be effective in relieving coarctation of the aorta. However, restenosis frequently occurs after balloon angioplasty for native aortic coarctation in small infants, and sometimes develops after stent implantation because of vessel growth. The causes of restenosis remain uncertain. The purpose of this study was to assess the histologic differences in vascular responses to angioplasty using conventional balloon, radiofrequency thermal balloon (RFTB), or stent for experimental aortic coarctation.

METHODS

The authors surgically created an aortic coarctation model using 14 puppies. Angioplasty using conventional balloon, RFTB, or stent was performed 1 month after the initial operation. At the acute or chronic phase after angioplasty, the animals were killed and histologic studies were performed.

RESULTS

More vascular injuries were noted in the specimens from animals undergoing conventional angioplasty than in those with RFTB or stent. However, neointimal hyperplasia was seen more often after RFTB or stent because of the proliferation of smooth muscle cells from the tunica media, caused by secretion of growth factors. Apoptosis reached a peak 1-2 weeks after angioplasty, regardless of the type of intervention.

CONCLUSIONS

The authors conclude that angioplasty with RFTB or stent can provide relatively small injuries in the vessel wall for aortic coarctation, but care must be taken to prevent restenosis caused by intimal hyperplasia, because neointima hyperplasia is more frequent after RFTB or stent.

Re-angioplasty of in-stent restenosis versus balloon restenoses—a matched pair comparison

BACKGROUND

Despite different biological mechanisms involved in the restenotic process of in-stent restenosis and restenosis after balloon angioplasty alone, the occurrence of a second restenosis has been reported in the same range. There are no data available comparing the outcome after re-angioplasty of such lesions. We analyzed in a matched pair comparison the clinical outcome and angiographic long-term result of patients with balloon angioplasty of a first in-stent restenosis versus patients with balloon re-angioplasty of a first balloon restenosis.

METHODS

Both groups consisted of 74 lesions matched by treated vessel, lesion location differentiated in proximal and non-proximal, and angiographic appearance of coronary artery disease differentiated in singular stenosis, diffuse or mixed pattern. Clinical follow-up was 100%. Angiographic follow-up was 78.4% after median 174 days.

RESULTS

Angiographic restenosis rate in matched pairs of patients (n=46/74) was significantly higher in the balloon restenosis group (41.3%, n=19/46) compared to the in-stent restenosis group (21.7%, n=10/46, p<0.042). There was no death or myocardial infarction. After clinical follow-up, target lesion revascularization rate was significantly lower in the in-stent restenosis group compared to the balloon restenosis group (12.1%, n=9/74 versus 27.0%, n=20/74; difference between groups 14.9%, 95% confidence interval 2.0-27.3%, p<0.023). Multivariate logistic regression analysis revealed as predictors for a second restenosis unstable angina pectoris, non-proximal lesion, restenosis after balloon angioplasty and the occurrence of the first restenosis within 90 days after initial intervention.

CONCLUSION

Clinical and angiographic outcome after balloon angioplasty of a first in-stent restenosis was significantly better compared with balloon re-angioplasty of a first balloon restenosis.

High plasma heparin cofactor II activity is associated with reduced incidence of in-stent restenosis after percutaneous coronary intervention

BACKGROUND

Thrombin plays an important role in the development of atherosclerosis and restenosis after percutaneous coronary intervention. Because heparin cofactor II (HCII) inhibits thrombin action in the presence of dermatan sulfate, which is abundantly present in arterial wall, HCII may affect vascular remodeling by modulating thrombin action. We hypothesized that patients with high plasma HCII activity may show a reduced incidence of in-stent restenosis (ISR).

METHODS AND RESULTS

Sequential coronary arteries (n=166) with NIR stent (Boston Scientific Corp) implantation in 134 patients were evaluated before, immediately after, and at 6 months after percutaneous coronary intervention. Patients were divided into the following groups: high HCII (> or =110%, 45 lesions in 36 patients), normal HCII (> or =80% and <110%, 81 lesions in 66 patients), and low HCII (<80%, 40 lesions in 32 patients). Percent diameter stenosis at follow-up in the high-HCII group (18.7%) was significantly lower (P=0.046) than that in the normal-HCII group (30.3%) or the low-HCII group (29.0%). The ISR rate in the high-HCII group (6.7%) was significantly lower than that in the low-HCII group (30.0%) (P=0.0039). Furthermore, multivariate analysis demonstrated that high plasma HCII activity is an independent factor in reducing the incidence of angiographic restenosis (odds ratio, 0.953/1% increase of HCII; 95% CI, 0.911 to 0.998).

CONCLUSIONS

The results demonstrate that HCII may have a hitherto unrecognized effect in inhibiting ISR. The effect of HCII may be mediated by inactivating thrombin in injured arteries, thereby inhibiting vascular smooth muscle cell migration and proliferation.

Granulation Tissue With Eosinophil Infiltration in the Restenotic Lesion After Coronary Stent Implantation-A Case Report-

Although stents reduce the rate of vessel restenosis, in-stent restenosis is a recognized clinical problem and it appears that patients positive for allergic patch-test reactions to the stent components nickel and molybdenum have increased rates of it. A patient with angina pectoris had repeated episodes of restenosis after stent implantation and histological examination demonstrated granulation tissue with eosinophil infiltration in the restenotic lesion of the coronary artery. The patient was positive for an allergic reaction to the stent components.