Effects of Combined Treatment with Angiotensin II Type 1 Receptor Blocker and Statin on Stent Restenosis

An overview of in-stent restenosis in iliofemoral venous stents

BACKGROUND

Although endovenous stents have been associated with overall low morbidity, they can require reinterventions to correct stent malfunction due to in-stent restenosis (ISR). ISR has often occurred iliofemoral venous stents but has not been well described. It has been reported to develop in >70% of patients who have undergone iliofemoral venous stenting. We sought to provide an overview of ISR in iliofemoral venous stents, including the pathologic, diagnostic, and management considerations and the identification of several areas of potential research in the future.

METHODS

A search of reported English-language studies was performed in PubMed and the Cochrane Library. "In-stent restenosis," "vein," "venous," "iliac," and "iliofemoral" were used as keywords. The pertinent reports included in the present review had addressed the pathology, diagnosis, and current management options for ISR.

RESULTS

ISR refers to the narrowing of the luminal caliber of the stent owing to the development of stenosis inside the stent itself. ISR should be differentiated from stent compression. Two main types of ISR have been described: soft and hard lesions. These lesions respond differently to angioplasty. Stent inflow and shear stress are important factors in the development of ISR. The treatment options available at present include balloon angioplasty (hyperdilation or isodilation), laser ablation, atherectomy, and Z-stent placement.

CONCLUSIONS

Reintervention for ISR should be determined by the presence of residual or recurrent symptoms and not simply by a numeric value obtained from an imaging study. Overall stent occlusion due to ISR is rare, and no role exists for prophylactic angioplasty to treat asymptomatic ISR. The current treatment options for ISR are mostly durable and effective. However, more research is needed on methods to prevent the development of ISR. The role of antiplatelet and anticoagulant agents in the prevention of ISR requires further investigation, with particular attention to unique subset of patients (after thrombosis vs nonthrombotic iliac vein lesions). For high-risk, post-thrombotic patients, anticoagulation can be considered to prevent ISR. The role of triple therapy (anticoagulation and dual antiplatelet therapy) in the prevention of ISR remains unclear.

Atheroprotective effects of statins in patients with unstable angina by regulating the blood-borne microRNA network

Experimental studies have demonstrated several effects of statins in acute coronary syndrome (ACS) that may extend their clinical benefit beyond the lipid profile modification itself. However, the precise underlying mechanism remains to be elucidated. microRNAs (miRNAs) serve significant roles in the pathophysiology of atherosclerotic plaque progression. The present study investigated the protective role of statins in patients with unstable angina (UA) by regulating the circulating miRNA network. miRNA array results demonstrated that there were 21 differentially expressed miRNAs in non-statin-treated patients with UA (n=8) compared with non-coronary artery disease controls (n=8), and 33 differentially expressed miRNAs in statin-treated patients with UA (n=8) compared with non-statin patients. TargetScan and miRanda programs were used to predict miRNAs target genes. miRNAs target genes in vascular endothelial cells and monocytes were clustered based on the CGAP SAGE library via the Database for Annotation, Visualization and Integrated Discovery (DAVID) platform, and miRNA target genes in platelets were clustered based on a UP tissue-specific library via the DAVID platform. The PANTHER database via DAVID platform was used to perform signaling pathway analysis. The miRNA-gene/pathway network was visualized by Cytoscape software. Bioinformatic analysis suggested that statin-induced miRNAs functions were primarily enriched in angiogenesis, integrin and platelet derived growth factor signaling pathways in UA patients. In endothelial cells and platelets, statin-induced miRNAs primarily targeted the integrin signaling pathway, and in monocytes primarily targeted cytoskeletal regulation by the Rho GTPase signaling pathway. These results revealed that statins may serve systematic protective roles in UA patients by influencing the circulating miRNA regulatory network. Further studies are required to verify the functions of statin-induced miRNAs in endothelial cells, platelets and monocytes.

Renin-angiotensin system inhibitors in patients with coronary artery disease who have undergone percutaneous coronary intervention

The percutaneous coronary intervention (PCI) procedure has become one of the pivotal options in the treatment of coronary artery disease (CAD). Although the PCI procedure has rapidly developed in China, some concerns including in-stent restenosis and dissatisfactory long-term prognosis remain unsolved. Large-scale randomized controlled clinical trials indicate that angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) can reduce all-cause mortality and recurrent cardiac events in patients with CAD. ACEIs/ARBs are recommended as a fundamental treatment in the secondary prevention of CAD and reduce in-stent restenosis after PCI. This review focuses on the role of ACEIs/ARBs in improving long-term prognosis and reducing in-stent restenosis.

BMSCs Interactions with Adventitial Fibroblasts Display Smooth Muscle Cell Lineage Potential in Differentiation and Migration That Contributes to Neointimal Formation

In this study a model of simulated vascular injury in vitro was used to study the characterization of bone-marrow-derived mesenchymal stem cells (BMSCs) morphology and to investigate the differentiation and migration of BMSCs in the presence of adventitial fibroblasts. BMSCs from rats were indirectly cocultured with adventitial fibroblasts in a transwell chamber apparatus for 7 days, and clonogenic assays demonstrated that BMSCs could be differentiated into smooth muscle-like cells with this process, including smooth muscle α-actin (α-SMA) expression by immunofluorescence staining. Cell morphology of BMSCs was assessed by inverted microscope, while cell proliferation was assessed by MTT assay. The expressions of TGF-β1, MMP-1, and NF-κB were detected by immunofluorescence staining and Smad3 mRNA was measured by reverse transcription PCR. Migration ability of BMSCs with DAPI-labeled nuclei was measured by laser confocal microscopy. Our results demonstrate that indirect interactions with adventitial fibroblasts can induce proliferation, differentiation, and migration of BMSCs that can actively participate in neointimal formation. Our results indicate that the pathogenesis of vascular remodeling might perform via TGF-β1/Smad3 signal transduction pathways.

The Role of Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers in Postangioplasty Restenosis

Postangioplasty restenosis remains a clinical problem, and various strategies have been used to minimize or eliminate this complication. Stimulation of the renin-angiotensin system has been shown to cause vascular smooth muscle migration, matrix deposition, and endothelial dysfunction, which are possible causes of postangioplasty restenosis, suggesting that the use of angiotensin-converting enzyme (ACE) inhibitors and/or angiotensin receptor blockers might ameliorate or prevent restenosis. However, data obtained to date in both animal and human studies of various designs show conflicting results regarding the benefit or lack of benefit of angiotensin inhibition strategies. It has also been shown that the type of ACE genotype may influence the effects of drugs on restenosis, suggesting that in the future, a pharmacogenetic approach might be of use for augmenting the benefit in patients from inhibitors of the angiotensin system. As of now, there are no supportive data to suggest a benefit of using routine ACE inhibitors or angiotensin receptor blockers to prevent postangioplasty restenosis in the general population.

Differential metabolic actions of specific statins: clinical and therapeutic considerations

SIGNIFICANCE

Statins, the most widely prescribed drugs in clinical practice, mainly act by reducing the plasma level of low-density lipoprotein (LDL)-cholesterol. A shift in redox homeostasis to an imbalance between reactive oxygen species generation and endogenous antioxidant mechanisms results in oxidative stress that has been implicated in the pathogenesis of various diseases, including those of the cardiovascular system. Beyond their efficacy in lowering LDL cholesterol, statins modulate redox systems that are implicated in the development of atherosclerosis, cardiovascular morbidity, and mortality.

RECENT ADVANCES

Differences in specific statins or their dosages result in differential metabolic actions arising from off-target or unknown mechanisms of action that can have important implications for overall patient morbidity and mortality.

CRITICAL ISSUES

A recent meta-analysis and a combined analysis have suggested that high doses of statins increase the risk of developing type 2 diabetes mellitus, but reduce the risk of cardiovascular events. Thus, it is important to consider the cardiovascular and metabolic context and natural history of diseases when choosing a specific statin therapy for optimal individual patient health over the long term.

FUTURE DIRECTIONS

More information is needed regarding the metabolism of statins, and the off-target or unknown actions of statins in affecting insulin resistance and metabolic homeostasis. The differential metabolic effects of specific statins should be considered in formulating optimal therapeutic strategies to reduce not just cardiovascular-related but also overall patient morbidity and mortality.

Controlling the proliferation and differentiation stages to initiate periodontal regeneration

The success of periodontal regeneration depends on the coordination of early cell proliferation and late cell differentiation. The aim of this study was to investigate whether the proliferation or differentiation stage predominantly promotes the initiation of periodontal regeneration. Critical-sized periodontal defects were surgically created on rat maxillae and filled with poly-(D,L-lactide-co-glycolide)-poly-d,l-lactide hybrid microspheres encapsulating platelet-derived growth factor (PDGF, a promoter of mitogenesis), simvastatin (a promoter of osteogenic differentiation), or bovine serum albumin (a control). The encapsulation efficiency and in vitro release profiles of the microspheres were determined by high-performance liquid chromatography and enzyme-linked immunosorbent assay. The maxillae were harvested after 10 or 14 days and assessed by micro-computed tomography, histology, and immunohistochemistry for regeneration efficacy and cell viability. The rapid release of PDGF was observed within the first week, whereas a slow release profile was noted for simvastatin. The PDGF-treated specimens demonstrated a significantly higher bone volume fraction compared with bovine serum albumin- (p < 0.05) or simvastatin-treated (p < 0.05) specimens at day 14. Histologically, active bone formation originating from the defect borders was noted in both the PDGF- and the simvastatin-treated specimens, and functionally aligned periodontal ligament fiber insertion was only observed in the PDGF-treated specimens. The significant promotion of mitogenesis by PDGF treatment was also noted at day 14 (p < 0.05). In conclusion, increased mitogenesis or osteogenic differentiation may stimulate osteogenesis, and the upregulation of mitogenesis by PDGF appears to play a role in the initiation of periodontal regeneration.

The effects of low-dose fluvastatin and valsartan combination on arterial function: a randomized clinical trial

BACKGROUND

Ageing progressively diminishes arterial functions, even in the absence of traditional risk factors. Our aim was to explore whether age-related arterial changes in middle-aged males could be reversed using short-term, low-dose fluvastatin/valsartan combination intervention.

METHODS

Forty apparently healthy, middle-aged males (43.3 ± 5.8 years) were recruited in a double-blind, randomised intervention. Individuals received either 10mg fluvastatin/20mg valsartan daily or placebo over 30 days. The brachial artery flow mediated dilation (FMD), pulse wave velocity (PWV) and common carotid artery β-stiffness were assessed at baseline and after 30 days, and again 5-10 months after therapy discontinuation.

RESULTS

Arterial function variables significantly improved after 30 days of intervention; FMD improved by 167.7% (P<0.001), PWV by 10.9% (P<0.05) and β-stiffness by 18.8% (P<0.01), whereas no changes were obtained in the placebo group. The favourable outcomes in the intervention group were accompanied by a significant decrease of high sensitivity-C reactive protein levels (1.8-fold; P<0.05). In contrast, lipids and blood pressure remained unchanged. Surprisingly, the beneficial arterial effects were still present to a substantial degree 7 months after completing intervention (remaining % of initial improvement: FMD 82.1%, PWV 69.5% and β-stiffness 68.5%), but declined substantially after 10 months.

CONCLUSION

Our results indicate that age-related arterial changes, at least in middle-aged males, can be reversed. Short-term treatment with a low-dose fluvastatin/valsartan combination resulted in a large and long lasting improvement of arterial function.

Neointimal hyperplasia inhibition effect of angiotensin II type 1 receptor blockers in patients after coronary stent implantation: a meta-analysis

BACKGROUND AND OBJECTIVE

It remains unclear whether angiotensin II type 1 receptor antagonists (angiotensin receptor blockers [ARBs]) can inhibit neointimal hyperplasia after stent implantation in patients with coronary artery disease. The aim of this meta-analysis was therefore to evaluate the benefits of ARBs in patients after coronary stent implantation based on the currently available randomized controlled trials.

METHODS

We conducted a pooled analysis of randomized controlled trials to compare outcomes after stent implantation in patients administered ARBs with those not administered ARBs. We searched Ovid/MEDLINE, EMBASE, and the ISI web of knowledge using the terms 'angiotensin receptor blocker,' 'renin angiotensin system inhibitor,' 'angiotensin receptor antagonist,' 'stent,' 'angiograph,' 'percutaneous coronary intervention (PCI),' and 'coronary artery disease.' Published meta-analyses, review articles, and editorials were reviewed for potential studies of interest. The inclusion criteria were randomized controlled trials published in English, with a follow-up period of 6 months, comparing the outcomes after coronary stent implantation with and without the administration of any kind of ARB, reporting at least one outcome of interest (restenosis rate and late lumen loss). Data abstraction included study design, patient characteristics, follow-up period, type of ARB, type of stent, restenosis rate, and late lumen loss. Fixed-effects models were used to calculate the pooled relative risk for the restenosis rate and the standardized mean difference for late lumen loss.

RESULTS

Five studies were included, with a total number of 624 patients. Seventy-five of 314 patients in the ARB group were diagnosed with in-stent restenosis at the 6-month follow-up, compared with 87 of 310 patients in the control group (relative risk 0.85; 95% CI 0.65, 1.11; p = 0.23). Consistent with this, there was no significant difference in late lumen loss between the two groups (0.04 mm; 95% CI -0.15, 0.23; p = 0.66).

CONCLUSION

There is no evident benefit with the use of an ARB in terms of inhibition of neointimal hyperplasia in patients after coronary stent implantation.

Angiotensin receptor blockers and antiplatelet agents are associated with improved primary patency after arteriovenous hemodialysis access placement

OBJECTIVE

Dialysis access failure is a major cause of morbidity, mortality, and cost in end-stage renal disease. We undertook a study to determine the influence of medication use on dialysis access failure.

METHODS

After institutional review board approval, we performed a retrospective analysis of all upper extremity hemodialysis accesses placed from 2005 to 2009 at the Washington DC Veterans Affairs Medical Center. For each access, the date of failure was recorded. For patients who died or were lost to follow-up, the date of the last documented functional patency (censoring) was recorded. The primary exposures were 12 medication classes. Patient demographics, behaviors, comorbidities, and access characteristics were used as covariates. Patency rates were calculated using Kaplan-Meier methods. Cox proportional hazard models controlling for patient characteristics and all medication classes, with procedures clustered within patients, were used to determine the influence of medication class on primary patency.

RESULTS

Two hundred sixty autogenous and 126 prosthetic newly placed accesses were identified. Of these, three lower extremity accesses and six accesses with unknown thrombosis date were excluded. Forty-five (18%) of the remaining 257 autogenous accesses were excluded for primary nonfunctionality (patent, but with inadequate venous dilatation for initial hemodialysis), because the primary outcome was long-term functional patency. The remaining 212 autogenous and 120 prosthetic accesses were analyzed. Primary patency rates at 1 and 2 years were 55.2% and 49.1% for autogenous accesses, and 50.2% and 29.7% for prosthetic accesses, respectively. On multivariable analysis, angiotensin receptor blockers (ARBs) were associated with reduced hazard of both autogenous (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.16-0.76; P = .008) and prosthetic (HR, 0.41; 95% CI, 0.18-0.95;P = .039) access failure. On subgroup analysis, ARBs prolonged autogenous access primary patency among patients receiving antiplatelet medication (aspirin, clopidogrel; HR, 0.16; 95% CI, 0.05-0.52;P = .002) but had no demonstrable benefit among patients not receiving antiplatelets (HR, 1.35; 95% CI, 0.34-5.31;P = .670). There were no significant drug-drug interactions in the analysis of prosthetic accesses. Weighted regression models demonstrated low multicollinearity among the model variables.

CONCLUSION

Our data suggest that therapy with an ARB plus antiplatelet agent is associated with prolonged autogenous access primary patency, and therapy with an ARB with or without antiplatelet agents is associated with prolonged prosthetic access primary patency. Randomized studies are needed to confirm the causal role of ARBs and to determine the optimal therapeutic regimen (dose, timing, and duration) to promote access patency.

Inhibitory effects of simvastatin on platelet-derived growth factor signaling in pulmonary artery smooth muscle cells from patients with idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a progressive disease characterized by inappropriate increase of pulmonary artery smooth muscle cells (PASMCs) leading to occlusion of pulmonary arterioles. Inhibition of platelet-derived growth factor (PDGF) signaling is starting to garner attention as a targeted therapy for IPAH. We assessed the inhibitory effects of simvastatin, a 3-hydroxy-3-methylglutanyl coenzyme A reductase inhibitor, on PDGF-induced proliferation and migration of PASMCs obtained from 6 patients with IPAH who underwent lung transplantation. PDGF stimulation caused a significantly higher growth rate of PASMCs from patients with IPAH than that of normal control PASMCs as assessed by (3)H-thymidine incorporation. Simvastatin (0.1 micromol/L) significantly inhibited PDGF-induced cell proliferation of PASMCs from patients with IPAH but did not inhibit proliferation of normal control cells at the same concentration. Western blot analysis revealed that simvastatin significantly increased the expression of cell cycle inhibitor p27. PDGF significantly increased the migration distance of IPAH-PASMCs compared with that of normal PASMCs, and simvastatin (1 micromol/L) significantly inhibited PDGF-induced migration. Immunofluorescence staining revealed that simvastatin (1 micromol/L) inhibited translocation of Rho A from the cytoplasm to membrane and disorganized actin fibers in PASMCs from patients with IPAH. In conclusion, simvastatin had inhibitory effects on inappropriate PDGF signaling in PASMCs from patients with IPAH.

4-Hydroxy-2-nonenal induces calcium overload via the generation of reactive oxygen species in isolated rat cardiac myocytes

BACKGROUND

It has been reported that that the amount of 4-hydroxy-2-nonenal (HNE), which is a major lipid peroxidation product and a cytotoxic aldehyde, is increased in the human failing myocardium. This study was designed to determine whether HNE has a pro-oxidant effect in cardiac myocytes and whether HNE causes Ca(2+) overload.

METHODS AND RESULTS

Exposure to HNE for 10 minutes in the presence of ferric nitrilotriacetate induced the production of hydroxyl radical (.OH) in the rat myocardium as assessed by electron spin resonance spectroscopy, and HNE induced the generation of reactive oxygen species (ROS) in a dose-dependent manner as assessed by 2', 7'-dichlorofluorescein diacetate fluorescence. HNE increased intracellular Ca(2+) concentration ([Ca(2+)](i)) as assessed by fura-2 ratio in a dose- and time-dependent manner. After 20 minutes of HNE (400 micromol/L) exposure, hypercontracture was induced in 67% of the cells. Catalase, an antioxidative enzyme that can decompose hydrogen peroxide (H(2)O(2)), significantly attenuated the increase in [Ca(2+)](i) and completely inhibited hypercontracture. Carvedilol, a beta-blocker with potent antioxidant activity, also significantly attenuated the increase in [Ca(2+)](i) and completely inhibited hypercontracture, but propranolol had no effect on either [Ca(2+)](i) increase or hypercontracture.

CONCLUSIONS

HNE induces the formation of ROS, especially H(2)O(2) and .OH, in cardiomyocytes and subsequently ROS cause intracellular Ca(2+) overload. HNE formation may play an important role as a mediator of oxidative stress in heart failure.