Mechanism of late in-stent restenosis after implantation of a paclitaxel derivate-eluting polymer stent system in humans

Current Management of In-Stent Restenosis

In-stent restenosis (ISR) remains the primary cause of target lesion failure following percutaneous coronary intervention (PCI), resulting in 10-year incidences of target lesion revascularization at a rate of approximately 20%. The treatment of ISR is challenging due to its inherent propensity for recurrence and varying susceptibility to available strategies, influenced by a complex interplay between clinical and lesion-specific conditions. Given the multiple mechanisms contributing to the development of ISR, proper identification of the underlying substrate, especially by using intravascular imaging, becomes pivotal as it can indicate distinct therapeutic requirements. Among standalone treatments, drug-coated balloon (DCB) angioplasty and drug-eluting stent (DES) implantation have been the most effective. The main advantage of a DCB-based approach is the avoidance of an additional metallic layer, which may otherwise enhance neointimal hyperplasia, provide the substratum for developing neoatherosclerosis, and expose the patient to a persistently higher risk of coronary ischemic events. On the other hand, target vessel scaffolding by DES implantation confers relevant mechanical advantages over DCB angioplasty, generally resulting in larger luminal gain, while drug elution from the stent surface ensures the inhibition of neointimal hyperplasia. Nevertheless, repeat stenting with DES also implies an additional permanent metallic layer that may reiterate and promote the mechanisms leading to ISR. Against this background, the selection of either DCB or DES on a patient- and lesion-specific basis as well as the implementation of adjuvant treatments, including cutting/scoring balloons, intravascular lithotripsy, and rotational atherectomy, hold the potential to improve the effectiveness of ISR treatment over time. In this review, we comprehensively assessed the available evidence from randomized trials to define contemporary interventional treatment of ISR and provide insights for future directions.

Isolated Coronary Arteritis Treated With FDG-PET/CT-Guided Immunosuppressant to Break the Vicious Cycle of In-Stent Restenosis

Recurrent in-stent restenosis of the coronary artery is a rare but intractable problem. In this situation, coronary arteritis should be considered as an etiology. This case highlights the use of immunosuppressive drugs, including tocilizumab, and follow-up F-18-fluorodeoxyglucose positron emission tomography/computed tomography to break the vicious circle of recurrent stenosis caused by isolated coronary arteritis of unknown cause.

Exosomes Derived from Endothelial Cells Inhibit Neointimal Hyperplasia Induced by Carotid Artery Injury in Rats via ROS-NLRP3 Inflammasome Pathway

This study attempted to investigate whether exosomes derived from rat endothelial cells (EC-Exo) attenuate intimal hyperplasia after balloon injury using hematoxylin and eosin staining, immunohistochemistry, immunofluorescence staining, Evans blue staining, and Western blotting. The results indicated that EC-Exo inhibited intimal hyperplasia in the carotid artery after balloon injury, promoted re-endothelialization, and reduced vascular inflammation and ROS-NLRP3-mediated cell pyroptosis. Thus, EC-Exo can inhibit neointimal hyperplasia after carotid artery injury in rats presumably by inhibiting the ROS-NLRP3 inflammasome and phenotypic transformation of vascular smooth muscle cells.

Comparing the impact of the loss of patency between treatment with drug-coated balloon angioplasty and drug-eluting stent placement

OBJECTIVE

To compare the results of endovascular treatment with drug-eluting stents (DES) and drug-coated balloons (DCB) in atherosclerotic lesions in the femoropopliteal artery, as well as to assess restenotic patterns.

METHODS

Clinical data from 617 cases treated with DES or DCB for femoropopliteal diseases were analyzed in this multicenter, retrospective cohort study. From these, 290 DES and 145 DCB cases were extracted by propensity score matching. Outcomes investigated were 1- and 2-year primary patency, reintervention, and restenotic pattern and its impact on symptoms in each group.

RESULTS

The primary patency rates at 1 and 2 years in the DES group were superior to those in the DCB group (84.8% and 71.1% vs 81.3% and 66.6%, P = .043), whereas there was no significant difference in freedom from target lesion revascularization (91.6% and 82.6% vs 88.3% and 78.8%, P = .13). Compared with what was measured before the index procedures, exacerbated symptoms, rate of occlusion, and an increase in the occluded length at loss of patency were more frequent in the DES group than in the DCB group. The odds ratios were 3.53 (95% confidence interval, 1.31-9.49; P = .012), 3.61 (1.09-11.9; P = .036), and 3.82 (1.15-12.7; P = .029), respectively. On the other hand, the frequency of an increase in lesion length and requirement of target lesion revascularization were similar between the two groups.

CONCLUSIONS

Primary patency was significantly higher at 1 and 2 years in the DES than in the DCB group. However, DES were associated with exacerbated clinical symptoms and complicated lesion characteristics at the point of loss of patency.

Combinational Growth Factor and Gas Delivery for Thrombosis Prevention

Cardiovascular stents enable the rapid re-endothelialization of endothelial cells (ECs), and the constant suppression of smooth muscle cell (SMC) proliferation has been proved to effectively prevent thrombosis. However, the development and application of such stents are still insufficient due the delayed re-endothelialization progress, as well as the poor durability of the SMC inhibition. In this paper, we developed a mussel-inspired coating with the ability for the dual delivery of both growth factor (e.g., platelet-derived growth factor, PDGF) and therapeutic gas (e.g., nitric oxide, NO) for thrombosis prevention. We firstly synthesized the mussel-inspired co-polymer (DMHM) of dopamine methacrylamide (DMA) and hydroxyethyl methacrylate (HEMA) and then coated the DMHM on 316L SS stents combined with CuII. Afterwards, we immobilized the PDGF on the DMHM-coated stent and found that the PDGF could be released in the first 3 days to enhance the recruitment, proliferation, and migration of human umbilical vein endothelial cells (HUVECs) to promote re-endothelialization. The CuII could be “sealed” in the DMHM coating, with extended durability (2 months), with the capacity for catalyzed NO generation for up to 2 months to suppress the proliferation of SMCs. Such a stent surface modification strategy could enhance the development of the cardiovascular stents for thrombosis prevention.

Stent Thrombosis After Percutaneous Coronary Intervention: From Bare-Metal to the Last Generation of Drug-Eluting Stents

Since their introduction in clinical practice in 1986, different types of coronary stents have been developed and become available for the treatment of coronary artery disease. Stent thrombosis (ST) is an uncommon but harmful complication after percutaneous coronary implantation, with a high occurrence of acute myocardial infarction and risk of mortality. Among several procedural and clinical predictors, the type of coronary stent is a strong determinant of ST. This article reviews the available evidence on the most used coronary stent types in the modern era and the related risk of ST.

Does the use of polymer-free drug eluting stents improve clinical outcomes of patients undergoing percutaneous coronary interventions?

BACKGROUND

Implantation of drug eluting stents (DES) is the mainstay treatment for patients requiring percutaneous coronary intervention (PCI). The polymer coating of DES has been associated with inflammatory response, increased arterial injury and long-term in-stent restenosis and thrombosis. Polymer-free stents (PFS) were designed to overcome limitations of polymer-coated stents (PCS). Our aim was to compare clinical outcomes of patients undergoing PCI with PFS versus contemporary PCS.

METHODS

This is a prospective, open-label registry study enrolling consecutive all-comers patients admitted to a single center and undergoing PCI using contemporary DES. Clinical outcomes were compared between patients treated with PFS and PCS. The primary endpoint was target lesion revascularization (TLR) at 12 months. Subgroup analyses were conducted for diabetic and nondiabetic patients.

RESULTS

Overall, 1664 patients were included: 928 (55.8%) of which were treated with PFS and 736 (44.2%) with PCS for 2046 and 1462 lesions, respectively. At 12 months, TLR rates were not significantly different between the groups (1.7% vs. 2.3% for PFS and PCS, respectively, P = 0.48). The use of PFS did not improve clinical outcomes among diabetic patients in comparison with PCS. Target vessel revascularization and major adverse cardiac events rates were also similar between groups, regardless of diabetes status.

CONCLUSION

Newer generation DES offer excellent results in diabetic and nondiabetic patients without significant differences in outcomes between PCS and PFS.

pH-Responsive Nanoparticles for Delivery of Paclitaxel to the Injury Site for Inhibiting Vascular Restenosis

A high incidence of restenosis has been reported at the site of inflammation following angioplasty and stent implantation. The anti-proliferative drug paclitaxel (PTX) could help to reduce inflammation and restenosis; however, it has poor water solubility and serious adverse side effects at high doses. Given the presence of metabolic acidosis at the site of inflammation, we hypothesized that nanoparticles that are responsive to low pH could precisely release the loaded drug at the target site. We successfully constructed pH-responsive poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles loaded with PTX and NaHCO3 as a pH-sensitive therapeutic agent (PTX-NaHCO3-PLGA NPs). The NPs exhibited remarkable pH sensitivity and a good safety profile both in vitro in rat vascular smooth muscle cells and in vivo in Sprague Dawley rats after tail vein injection. In the rat model, the PTX-NaHCO3-PLGA NPs treatment group showed suppressed intimal proliferation following balloon-induced carotid artery injury compared with that of the saline-treated control. Overall, these results demonstrate that our newly developed pH-responsive nanodrug delivery platform has the potential to effectively inhibit restenosis.

Aneurysmal degeneration of fluoropolymer-coated paclitaxel-eluting stent in the superficial femoral artery: a rising concern

BACKGROUND

Although several clinical reports demonstrated a durable patency rate after a novel fluoropolymer-coated paclitaxel-eluting stent (Eluvia; Boston Scientific, Marlborough, MA, USA) placement, aneurysmal degeneration after drug-eluting stent (Eluvia) placement has raised clinical concerns. Here, we report a case with progressive aneurysm formation on serial angiography and intravascular ultrasound over 50 months after drug-eluting stent (Eluvia) placement for a superficial femoral artery atheromatous plaque.

CASE PRESENTATION

A 79-year-old woman with right leg intermittent claudication at 100 m distance was referred to our hospital. Pre-procedural angiography showed long-segment severe stenosis from the middle-to-distal part of the right superficial femoral artery, and a 7 mm wide drug-eluting stent (Eluvia) was placed. However, the patient had a recurrence of intermittent claudication in the right lower extremity 25 months thereafter. Angiography revealed de novo stenosis in the distal part of the popliteal artery and proximal superficial femoral artery in-stent restenosis. Subsequently, the patient underwent endovascular therapy for these lesions. In addition, intravascular ultrasound at the time of endovascular therapy revealed femoral artery enlargement with a maximum vessel diameter of 10.0 mm at the distal edge of the stent. Intermittent claudication on the right side recurred again 50 months after drug-eluting stent (Eluvia). Angiography demonstrated de novo severe stenosis from the distal part of the superficial femoral artery to the middle part of the popliteal artery. Peri-stent contrast staining was found at the distal part of the drug-eluting stent (Eluvia) site. Intravascular ultrasound showed a further enlargement of maximum vessel diameter to 12.0 mm at the distal edge of the stent.

CONCLUSIONS

We report a case with progressive aneurysm degeneration on serial angiography and intravascular ultrasound over 50 months after drug-eluting stent (Eluvia) placement for a superficial femoral artery stenosis.

Stent Thrombosis After Percutaneous Coronary Intervention: From Bare-Metal to the Last Generation of Drug-Eluting Stents

Since their introduction in clinical practice in 1986, different types of coronary stents have been developed and become available for the treatment of coronary artery disease. Stent thrombosis (ST) is an uncommon but harmful complication after percutaneous coronary implantation, with a high occurrence of acute myocardial infarction and risk of mortality. Among several procedural and clinical predictors, the type of coronary stent is a strong determinant of ST. This article reviews the available evidence on the most used coronary stent types in the modern era and the related risk of ST.

Predictive value of serum CTRP9 and STIM1 for restenosis after cerebrovascular stent implantation and its relationship with vasoactive substances and inflammatory cytokines

Predictive value of serum complement Clq tumor necrosis factor-related protein 9 (CTRP9) and serum stromal interaction molecule 1 (STIM1) was investigated for restenosis after cerebrovascular stent implantation, as well as its relationship with vasoactive substances and inflammatory cytokines. In this prospective study, 128 patients with cerebral infarction treated with cerebrovascular stent implantation in Yantaishan Hospital were recruited. A total of 66 cases with restenosis after cerebrovascular stent implantation were included in group A, and 62 cases without stenosis were included in group B. Serum CTRP9 and STIM1 levels were measured by enzyme-linked immunosorbent assay (ELISA). ROC curves of serum CTRP9 and STIM1 levels in patients with postoperative restenosis were drawn. The vasoactive substances nitric oxide (NO), tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) were analyzed by ELISA. The correlation of serum CTRP9, STIM1 levels and NO, TNF-α, IL-6 were analyzed by Pearson correlation coefficient. Serum CTRP9 and NO levels in group A were significantly lower than those in group B. The levels of serum STIM1, TNF-α and IL-6 in group A were significantly higher than those in group B (P<0.001). The sensitivity and specificity of serum CTRP9 level in the diagnosis of restenosis after cerebrovascular stent implantation were, respectively, 59.68 and 75.76%. Those of serum STIM1 were, respectively, 87.10 and 46.97% and those of the combination of serum CTRP9 and STIM1 were 90.32 and 48.48%. Serum CTRP9 level was positively correlated with NO, and negatively correlated with TNF-α and IL-6. STIM1 was positively correlated with TNF-α and IL-6, and negatively correlated with NO (P<0.001). Serum CTRP9 level was significantly decreased in patients with restenosis after cerebrovascular stent implantation, while STIM1 level was significantly up-regulated. Both were correlated with the change of NO, IL-6 and TNF-α levels, therefore they could be used as biological indicators for prediction of restenosis after cerebrovascular stent implantation.

Final 3-Year Outcomes of MiStent Biodegradable Polymer Crystalline Sirolimus-Eluting Stent Versus Xience Permanent Polymer Everolimus-Eluting Stent: Insights From the DESSOLVE III All-Comers Randomized Trial

BACKGROUND

Numerous randomized clinical trials have demonstrated the superiority of thin-strut biodegradable polymer second-generation drug-eluting stent to the first-generation drug-eluting stent and the noninferiority to the thin-strut second-generation permanent polymer drug-eluting stent. Data on long-term clinical outcomes with a novel ultrathin drug-eluting stent, to date, are limited.

METHODS

The DESSOLVE III trial (Multicenter Randomized Study of the MiStent Sirolimus Eluting Absorbable Polymer Stent System for Revascularization of Coronary Arteries; n=1398) is a prospective, multicenter, single-blinded, all-comers, randomized controlled trial (NCT02385279), allocating in a 1:1 ratio to either ultrathin-strut biodegradable polymer MiStent sirolimus-eluting stent or to thin-strut permanent polymer Xience everolimus-eluting stent. The primary end point was device-oriented composite end point, defined as the composite of cardiac death, target vessel myocardial infarction, or clinically indicated target lesion revascularization. The secondary end point was patient-oriented composite end point, defined as the composite of all-cause mortality, any myocardial infarction, or any revascularization.

RESULTS

At 3 years, follow-up data were available in 1381 patients (98.8%). The primary end point of device-oriented composite end point occurred in 10.5% for MiStent sirolimus-eluting stent and in 11.5% for Xience everolimus-eluting stent (P=0.55). Rates of cardiac death (3.9% versus 3.8%; P=0.88), target vessel myocardial infarction (3.2% versus 2.5%; P=0.43), and clinically indicated target lesion revascularization (5.2% versus 6.5%; P=0.30) did not differ significantly between the 2 devices. The rate of definite or probable stent thrombosis was infrequent and similar between the 2 arms (1.2% versus 1.5%; P=0.64). The 90-day landmark analysis showed no significant difference in device-oriented composite end point between the 2 groups after polymer degradation of MiStent. The risk of patient-oriented composite end point was comparable between the 2 groups (22.7% versus 22.9%; P=0.34).

CONCLUSIONS

In the DESSOLVE III trial, early safety and efficacy with MiStent sirolimus-eluting bioabsorbable polymer-coated stent are confirmed at a longer term follow-up when compared with Xience everolimus-eluting permanent polymer-coated stent in a large all-comers population. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02385279.

Angioplasty or bare metal stent versus drug-eluting endovascular treatment in femoropopliteal artery disease: a systematic review and meta-analysis

INTRODUCTION

Endovascular treatment represents nowadays the preferred therapeutic approach for disabling femoro-popliteal arterial occlusive disease in fit patients. In the latest years, in order to improve short- and long-term outcomes, drug eluting devices have been developed. Drug coated balloons (DCB) and drug eluting stents (DES) are today employed in clinical practice, and several studies has been completed to assess their performance in different clinical scenarios. Objective of the present review and meta-analysis is to compare clinical results of different endovascular treatment modalities in the published literature in the last 10 years.

EVIDENCE ACQUISITION

A systematic review and meta-analysis following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement on the literature regarding direct comparisons between DCB, DES, bare metal stents (BMS) and Plain Old Balloon Angioplasty (POBA) has been conducted. Primary outcomes were considered Primary Patency and Target Lesion Revascularization (TLR) at 12 months. Analysis of late survival in different treatment groups was outside the scope of the present study and was therefore not included as main end point.

EVIDENCE SYNTHESIS

Meta analysis results confirm that DCB outperforms POBA in both primary patency (estimate OR=3.17, 95% CI: 2.10-4.76) and TLR (POBA estimate OR=3.59, 95% CI= 2.31-5.56). No clear evidences emerged comparing DES and BMS; however, DES were shown to fare better than BMS in terms of TLR when analyzing lesions <15 cm (OR 0.36, 95% CI: 0.35-0.36). Comparison of DCB and DES revealed higher rates of TLR for DES (OR 1.26 95% CI: 1.07-1.49), however no significant differences have been found regarding primary patency analyzing such long lesions (range 14-19.4 cm) as those included in the studies.

CONCLUSIONS

While confirming that DCB outperforms POBA in terms of primary patency and TLR at 12 months, only TLR benefits are noted for DES vs. BMS and DCB vs. DES in limited clinical settings. Further RCTs are needed to strongly assess the compared performance of drug eluting devices in relation to lesion length and controlling possible confounders.

Histological features of restenosis associated with paclitaxel drug-coated balloon: implications for therapy

PURPOSE

To investigate the cellular and extracellular changes induced by drug-coated balloons (DCB) in the treatment of superficial femoral artery (SFA) restenosis, and to compare histopathological features with those observed after plain old balloon angioplasty (POBA) from the same patients.

METHODS AND RESULTS

Plaque samples for five patients with SFA restenosis (first-time) after POBA were collected using atherectomy and DCB. These samples constitute the POBA restenosis group. The same five patients developed recurrent restenosis (RR) after DCB, at the same intervention site. These SFA-RR lesions were again treated using atherectomy and POBA. These samples constitute the DCB restenosis group. DCB restenosis group plaques showed significant reduction in neointima, smooth muscle cells, fibroblast densities, and Ki67 index; and increase in caspase 3, features of apoptosis and type III collagen deposition in comparison to the POBA restenosis group.

CONCLUSION

Plaque tissue from the DCB restenosis group show reductions in neointimal thickness, cellularity, and cellular proliferation, along with increased apoptosis, and Type III collagen content. These results suggest a different mechanistic pathway for DCB restenosis, in which neointimal proliferation is reduced but reparative fibrosis is increased. The treatment for SFA-RR after DCB may therefore benefit from different forms of therapy including scaffolding, rather than recurrent anti-proliferative therapy.

The Predictors of Target Lesion Revascularization and Rate of In-Stent Restenosis in the Second-Generation Drug-Eluting Stent Era

Objectives

The aim of our study was to investigate the predictors of target lesion revascularization (TLR) and to compare the in-stent restenosis (ISR) progression rates of different 2nd-generation drug-eluting stents (DES).

Background

The predictors of early and late TLR after 2nd-generation DES implantation have not been fully evaluated.

Methods

We analyzed 944 stented lesions from 394 patients who had at least two serial follow-up angiograms, using quantitative coronary angiography (QCA) analysis. The study endpoints were TLR and the velocity of diameter stenosis (DS) progression.

Results

TLR occurred in 58 lesions (6.1%) during the first angiographic follow-up period and 23 de novo lesions (2.4%) during the following second interval. Independent predictors for early TLR were diabetes mellitus (DM) (HR 2.58, 95% CI 1.29–5.15, p=0.007), previous percutaneous coronary intervention (PCI) (HR 2.41, 95% CI 1.03–5.65, p=0.043), and postprocedure DS% (HR 1.08, 95% CI 1.05–1.11, p<0.001, per 1%), while predictors of late TLR were previous PCI (HR 9.43, 95% CI 2.58-34.52, p=0.001) and serum C-reactive protein (CRP) (HR 1.60, 95% CI 1.28-2.00, p<0.001). The ISR progression velocity (by DS%) was 12.1 ±21.0%/year and 3.7 ±10.1%/year during the first and second follow-up periods, respectively, which had no significant difference (p>0.05) between the four types of DESs.

Conclusions

Our data showed that predictors for TLR may be different at different time intervals. DM, pervious PCI, and postprocedure DS could predict early TLR, while previous PCI and CRP level could predict late TLR. Contemporary DESs had similar rates of ISR progression rates.

Trial Registration

This study was retrospectively registered and approved by the institutional review board of Seoul National University Hospital (no. 1801–138-918).

The negative affectivity dimension of Type D personality is associated with in-stent neoatherosclerosis in coronary patients with percutaneous coronary intervention: An optical coherence tomography study

OBJECTIVE

In-stent neoatherosclerosis (ISNA) is involved in the pathogenesis of in-stent restenosis and major adverse cardiac events (MACE) in patients with coronary artery disease (CAD) after percutaneous coronary intervention (PCI). We aimed to explore the association between Type D personality and ISNA via in vivo optical coherence tomography (OCT).

METHODS

One hundred and fifty-six patients with CAD completed the Type D Scale-14 and underwent in vivo measurement of in-stent neoatherosclerosis by OCT. The Type D construct was analyzed as both the dichotomous and the dimension constructs.

RESULTS

After adjusting for demographic and clinical factors and presenting as a dichotomous construct, Type D personality was independently associated with the presence of in-stent neoatherosclerosis (odds ratio [OR] = 2.99, 95% confidence interval [CI] = 1.35-6.63, p = 0.007) and in-stent thin-cap fibroatheroma (OR = 2.81, 95% CI = 1.27-6.23, p = 0.01). Meanwhile, the multiple logistic regression also showed that the main effect of negative affectivity was an independent risk factor of in-stent neoatherosclerosis (OR = 1.85, 95% CI = 1.25-2.75, p = 0.002) and in-stent thin-cap fibroatheroma (OR = 1.77, 95% CI = 1.18-2.67, p = 0.006). However, the main effects of social inhibition with in-stent neoatherosclerosis and in-stent thin-cap fibroatheroma (OR = 0.98, 95% CI = 0.64-1.52, p = 0.94; OR = 0.94, 95% CI = 0.63-1.39, p = 0.75, respectively) as well as the interaction of negative affectivity and social inhibition were not significant (OR = 0.71, 95% CI = 0.69-1.81, p = 0.11; OR = 0.72, 95% CI = 0.47-1.08, p = 0.12, respectively).

CONCLUSIONS

Type D personality was found to be independently associated with in-stent neoatherosclerosis via OCT in patients with CAD after PCI. It was negative affectivity, not social inhibition, that affected the occurrence of the in-stent neoatherosclerosis, these results challenged the usefulness of the Type D construct. Our findings may provide new insights regarding the mechanisms of the association between Type D personality and MACE after PCI.

Novel Biomarkers for Coronary Restenosis Occurrence After Drug-Eluting Stent Implantation in Patients With Diabetes Having Stable Coronary Artery Disease

The purpose of the study was to assess whether the occurrence of restenosis is associated with CD45+ platelet count and neutrophil to lymphocyte ratio in patients with type 2 diabetes mellitus (DM) after drug-eluting stent (DES) implantation for stable coronary artery disease (CAD). The study comprised 126 patients, including 55 patients with type 2 DM and stable CAD who underwent elective coronary artery stenting with DES and follow-up angiography within 6 to 12 months. Blood samples were collected from each patient on the morning of the coronary angiography procedure. The variables related to in-stent restenosis were selected by logistic regression analysis. The logistic regression analysis showed that 2 inflammatory factors, CD45+ platelet count (odds ratio [OR] = 4.51, 95% confidence interval [CI]: 1.50-13.50, P = .007) and neutrophil to lymphocyte ratio (OR = 3.09, 95% CI: 1.05-9.10, P = .04), were significantly associated with the risk of in-stent restenosis after stenting with DES in patients with stable CAD and type 2 DM. A receiver operator characteristic curve analysis indicated that the area under the curve was 0.83% (0.05%; P < .001), which showed that the logistic model had good predictive accuracy (based on CD45+ platelet count and neutrophil to lymphocyte ratio) for the risk of in-stent restenosis development in DES in patients with CAD and type 2 DM. Two novel biomarkers of restenosis, CD45+ platelet count and neutrophil to lymphocyte ratio, may be effectively used to predict in-stent restenosis after DES implantation in patients with CAD and type 2 DM.

Controlled release of paclitaxel using a drug-eluting stent through modulation of the size of drug particles in vivo

Drug-eluting stents (DESs) are generally used in percutaneous coronary intervention. Paclitaxel (PTX) is widely used in DESs to suppress neointima, which causes restenosis. However, the PTX release profile is slow owing to its hydrophobic properties, resulting in negative effects on re-endothelialization in vessels. In this study, we assessed the effects of the controlled release of PTX particles of specific sizes on in-stent restenosis (ISR). PTX particle sizes were controlled by adjusting the evaporating temperature of the solvent from 25 to 80°C during ultrasonic coating, and DESs were prepared. The properties of prepared films and DESs were analyzed, and cell viability was assessed in vitro and in vivo. Poly(lactic-co-glycolic acid) (PLGA)/PTX500-loaded stents showed the most rapid release for 58 days, and smaller drug particles exhibited lower PTX release rates. In vivo, PLGA/PTX50-, PLGA/PTX250-, and PLGA/PTX500-loaded stents showed good efficacy for alleviating ISR as compared with bare metal stents and PLGA/PTX5-loaded stents. However, PLGA/PTX250- and PLGA/PTX500-loaded stents exhibited strut exposure and reduced recovery of the vascular compared with PLGA/PTX50-loaded stents. PTX drug particles of approximately 50 nm were most effective in vivo, and the control of particle size is a promising strategy for improving the performance of PTX-eluting stents. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2275-2283, 2018.

Coronary stents and vascular response to implantation: literature review

Drug-eluting stents (DESs) have minimized the limitations of bare-metal stents (BMSs) after percutaneous coronary interventions. Nevertheless, serious concerns remain about possible late complications of stenting, such as stent thrombosis (ST) and in-stent restenosis (ISR), although the introduction of second-generation DESs seems to have softened the phenomenon, compared to the first-generation ones. ST is a potentially catastrophic event, which has been markedly reduced by optimization of stent implantation, novel stent designs, and dual antiplatelet therapy. The exact mechanism to explain its occurrence is under investigation, and, realistically, multiple factors are responsible. ISR of BMSs has been previously considered as a stable condition with an early peak (at 6 months) of intimal hyperplasia, followed by a regression period beyond 1 year. On the contrary, both clinical and histologic studies of DESs have demonstrated evidence of continuous neointimal growth during long-term follow-up, named "late catch-up" phenomenon. The acknowledgment that ISR is a relatively benign clinical condition has been recently challenged by evidences which reported that patients with ISR can experience acute coronary syndromes. Intracoronary imaging is an invasive technology that allows identifying features of atherosclerotic plaque of stent implanted and of vascular healing after stenting; it is often used to complete diagnostic coronary angiography and to drive interventional procedures. Intracoronary optical coherence tomography is currently considered a state-of-the-art imaging technique; it provides, compared to intravascular ultrasound, better resolution (at least >10 times), allowing the detailed characterization of the superficial structure of the vessel wall. Imaging studies "in vivo," in agreement with histological findings, suggest that chronic inflammation and/or endothelial dysfunction may induce late de novo "neoatherosclerosis" inside both BMSs and DESs. So, neoatherosclerosis has become the prime suspect in the pathogenesis of late stent failure.

Phenotypic switching prevention and proliferation/migration inhibition of vascular smooth muscle cells by the ruthenium nitrosyl complex trans-[Ru(NO)Cl(cyclam](PF6 )2

OBJECTIVES

Vascular smooth muscle cell (VSMC) migration and proliferation at sites of vascular injury are both critical steps in the development of intimal hyperplasia (IH). Local delivery of nitric oxide (NO) largely prevents these events. Among the NO donors, tetraazamacrocyclic nitrosyl complexes, such as trans-[Ru(NO)Cl(cyclam)](PF₆ )₂ (cyclamNO), gained attention for their features, which include the possibility of being embedded in solid matrices, and ability to participate in a nitrite/NO catalytic conversion cycle.

METHODS

Methods used to evaluate cyclamNO activity: safety margin by NR and MTT; cell proliferation by 3H-thymidine incorporation and proliferating cell nuclear antigen (PCNA) expression; antimigratory properties by transwell and wound healing; prevention of cell phenotypic switching under platelet-derived growth factor type BB (PDGF-BB) stimuli by analysis of alpha smooth muscle actin (α-SMA) expression.

KEY FINDINGS

Cell proliferation and migration induced by PDGF-BB were significantly inhibited by cyclamNO. The ~60% reduction on expression of contractile protein α-SMA induced by PDGF-BB revealed VSMC phenotypic switching which is significantly prevented by cyclamNO. Compared to the NO donor sodium nitroprusside, cyclamNO showed to be significantly less cytotoxic.

CONCLUSIONS

With great potential to maintain VSMC functionality and prevent IH-associated events, cyclamNO might be a promissory drug for several applications in cardiovascular medicine, as in stents.

Macrophage infiltration of electrospun polyester fibers

Ibuprofen (IBU)-loaded fibrous PLA membranes can prevent peritendinous adhesion/granuloma formation and inflammation by reducing macrophage infiltration.

Crosslinked Polyurethane Coating on Vascular Stents for Enhanced X-ray Contrast

A coating of polyurethaneurea was made from a solution on the surface of metal stents. The influence of cleaning, etching, chemical and ion beam modification (plasma immersion ion implantation) of the metal surface on the adhesion strength of the polyurethaneurea was analysed. Polyurethaneurea films imbedded with tantalum particles as a radiopaque filler maintained their strength and elasticity and produced clear X-ray contrast images of vascular stents.

Drug Eluting Stent Technology

The authors discuss the mechanism of action, clinical trial data, and economic impact of both the paclitaxel and sirolimus drug eluting stents (DESs). Both DESs have been approved by the Food and Drug Administration for the treatment of native coronary arteries to prevent in-stent restenosis (ISR), which patients have experienced since the advent of balloon angioplasty and the bare metal stent. In-stent restenosis, which manifests itself as ischemic symptoms in patients, occurs as a result of the healing process after stent implantation. Until now, there has not been an effective method to prevent ISR. The sirolimus and paclitaxel DESs elute agents that act locally by different mechanisms to reduce neointimal hyperplasia, which is primarily responsible for ISR. Both DESs are capable of reducing the rate of ISR. There are certain physical and mechanistic differences between the 2 stents; the stents have not been compared head to head. Currently, they are indicated for uncomplicated native coronary lesions. Further investigation is needed to define their roles in the treatment of more complex lesions.

The Systems Biocompatibility of Coronary Stenting

The coronary stent has propelled our understanding of the term "biocompatibility." Stents are expanded at sites of arterial blockage and mechanically reestablish blood flow. This simplicity belies the complex reactions that occur when a stent contacts living substrates. Biocompatible seek to elicit the intended response; stents should perform rather than merely exist. Because performance is assessed in the patient, stent biocompatibility is the multiscale examination of material and cell, and of material, structure, and device in the context of cell, tissue, and organism. This review tracks major biomaterial advances in coronary stent design and discusses biocompatibility clinical performance.

A Rare Case of Complete Stent Fracture, Coronary Arterial Transection, and Pseudoaneurysm Formation Induced by Repeated Stenting

This report describes a rare asymptomatic case of complete stent fracture, coronary arterial transection, and pseudoaneurysm formation in response to repeated stenting. The proximal and distal ends of transected coronary artery were closed, and distal bypass was performed. Coronary arterial transection can occur in patients with repeated stenting as a long-term adverse event.

Sustained Efficacy and Arterial Drug Retention by a Fast Drug Eluting Cross-Linked Fatty Acid Coronary Stent Coating

The long held assumption that sustained drug elution from stent coatings over weeks to months is imperative for clinical efficacy has limited the choice for stent coating materials. We developed and evaluated an omega-3 fatty acid (O3FA) based stent coating that is 85% absorbed and elutes 97% of its Sirolimus analog (Corolimus) load within 8d of implantation. O3FA coated stents sustained drug levels in porcine coronary arteries similarly to those achieved by slow-eluting durable coated Cypher Select Plus Stents and with significantly lower levels of granuloma formation and luminal stenosis. Computational modeling confirmed that diffusion and binding constants of Corolimus and Sirolimus are identical and explained that the sustained retention of Corolimus was facilitated by binding to high affinity intracellular receptors (FKBP12). First in man outcomes were positive-unlike Cypher stents where late lumen loss drops over 6 month, there was a stable effect without diminution in the presence of O3FA. These results speak to a new paradigm whereby the safety of drug eluting stents can be optimized through the use of resorbable biocompatible coating materials with resorption kinetics that coincide with the dissociation and tissue elimination of receptor-bound drug.

Influence of insulin resistance on in-stent restenosis in patients undergoing coronary drug-eluting stent implantation after long-term angiographic follow-up

OBJECTIVE

Previous studies have reported that insulin resistance is related to early in-stent restenosis (ISR) after coronary stenting. This study aimed to evaluate the influence of insulin resistance on the long-term angiographic outcome in patients undergoing coronary drug-eluting stent (DES) implantation.

MATERIALS AND METHODS

Within a single hospital-based cohort of patients (n=529) who underwent coronary DES implantation, angiographic follow-up was performed successfully for 417 study patients at 12-48 months after coronary stenting. ISR was defined as stenosis of at least 50% of the luminal diameter. Fasting plasma glucose and fasting plasma insulin were measured. Insulin resistance was expressed by the homeostasis model assessment index (HOMA-IRI).

RESULTS

Among the 417 patients who completed angiographic follow-up (mean 17.5±10.2 months), 58 patients (13.9%) had ISR whereas the remaining 359 patients (86.1%) did not have ISR. Patients with ISR had higher insulin resistance index (IRI) than nonrestenosis patients (P=0.004). Multiple logistic regression analysis (logit) showed that IRI was associated significantly with ISR (adjusted odds ratio 1.476, 95% confidence interval 1.227-1.776; P<0.001). In the nondiabetes subgroup of 309 patients, IRI was higher in patients with ISR than in nonrestenosis patients, as confirmed in a separate logit analysis (adjusted odds ratio 1.456, 95% confidence interval 1.152-1.839; P=0.002). Multiple linear regression analysis showed that IRI was associated significantly with in-stent diameter stenosis degree (P=0.043).

CONCLUSION

Insulin resistance was associated with ISR in patients undergoing coronary DES implantation at long-term angiographic follow-up.

Metallic zinc exhibits optimal biocompatibility for bioabsorbable endovascular stents

Although corrosion resistant bare metal stents are considered generally effective, their permanent presence in a diseased artery is an increasingly recognized limitation due to the potential for long-term complications. We previously reported that metallic zinc exhibited an ideal biocorrosion rate within murine aortas, thus raising the possibility of zinc as a candidate base material for endovascular stenting applications. This study was undertaken to further assess the arterial biocompatibility of metallic zinc. Metallic zinc wires were punctured and advanced into the rat abdominal aorta lumen for up to 6.5months. This study demonstrated that metallic zinc did not provoke responses that often contribute to restenosis. Low cell densities and neointimal tissue thickness, along with tissue regeneration within the corroding implant, point to optimal biocompatibility of corroding zinc. Furthermore, the lack of progression in neointimal tissue thickness over 6.5months or the presence of smooth muscle cells near the zinc implant suggest that the products of zinc corrosion may suppress the activities of inflammatory and smooth muscle cells.

Local delivery of paclitaxel in the treatment of peripheral arterial disease

BACKGROUND

Despite advancements from balloon angioplasty to drug-eluting stents, primary patency rates after endovascular revascularization of peripheral artery disease have remained inferior compared to surgery. Endovascular revascularization has been limited by restenosis and mechanical stent failure. Thus, there is increased research into other nonstent-based local drug delivery modalities, which can provide an active drug to inhibit restenosis focally and avoid the risk of systemic adverse effects.

METHODS

This review will summarize the unique properties of paclitaxel and studies on paclitaxel local delivery for the treatment of peripheral artery disease. A MEDLINE search for relevant peer-reviewed scientific literature published in English was conducted. Search terms included but were not limited to paclitaxel pharmacodynamics, paclitaxel local drug delivery, and drug eluting balloons, with a focus on the use of paclitaxel in the context of coronary and peripheral vascular disease.

RESULTS

The primary search produced 182 results of which 51 papers were relevant. Of the 51 relevant papers, 27 were original research papers and 24 were either review papers, commentary or opinion papers.

CONCLUSIONS

Paclitaxel has several chemical properties, which make it ideal for local drug delivery including its hydrophobicity, ability to concentrate into the arterial intima layer and prolonged effect on cells even after brief exposure periods. Local delivery of paclitaxel via injection catheters, balloon catheters and coated balloons has shown encouraging results in terms of efficacy and safety in small-scale animal and clinical studies. Additional preclinical and clinical studies are needed to determine the long-term efficacy and safety of these treatments in humans.

A prospective, multi-centric, observational registry to evaluate performance of Excel™ DES in 'real world, all comers' patient population

OBJECTIVES

This study aims to assess the safety and efficacy of a biodegradable polymer-coated Rapamycin-Eluting Stent (Excel) used in conjunction with six-month dual antiplatelet therapy in daily practice.

BACKGROUND

The polymeric material of cardiac stents has been reported to adversely affect the safety profile of the drug-eluting stents and is also suspected to cause serious long-term complications. It has been proposed that the biodegradable polymer coatings may reduce such late-stage adverse effects.

METHODS

This is a prospective, multi-center registry of 654 patients from across 9 cardiology centers in India, who were enrolled and exclusively treated with Excel stents between February 2008 and May 2010. The recommended antiplatelet regimen included clopidogrel and aspirin for 6 months period, followed by lifelong aspirin therapy.

RESULTS

The study population included 46.94% diabetics, 24.31% smokers, 48.93% hypertensives and 14.98% hyperlipidemics. The cumulative rates of major adverse cardiac events were 0.153% at discharge and 1.38% at 12 months. The mean percentage of stenosis was 88.24 ± 9.17% No events occurred between 6 and 12 months.

CONCLUSIONS

This multi-center registry study on "real world, all comers" has, thus, showed that EXCEL™ stent which is PLA-coated biodegradable Rapamycin-Eluting Stent exhibited high efficacy and safety profile in treatment of patients undergoing PCI as evidenced by significantly lower rates of MACE and no case of stent thrombosis. There was no event even after DAPT was discontinued after 6 months.

A poly(lactide) stereocomplex structure with modified magnesium oxide and its effects in enhancing the mechanical properties and suppressing inflammation

Biodegradable polymers such as poly(L-lactide) (PLLA) have been widely utilized as materials for biomedical applications. However, the relatively poor mechanical properties of PLLA and its acid-induced cell inflammation brought about by the acidic byproducts during biodegradation pose severe problems. In this study, these drawbacks of PLLA are addressed using a stereocomplex structure, where oligo-D-lactide-grafted magnesium hydroxide (MgO-ODLA) is synthesized by grafting d-lactide onto the surface of magnesium hydroxide, which is then blended with a PLLA film. The structure, morphology, pH change, thermal and mechanical properties, in-vitro cytotoxicity, and inflammation effect of the MgO-ODLAs and their PLLA composites are evaluated through various analyses. The PLLA/MgO70-ODLA30 (0-20 wt%) composite with a stereocomplex structure shows a 20% increase in its tensile strength and an improvement in the modulus compared to its oligo-L-lactide (PLLA/MgO70-OLLA30) counterpart. The interfacial interaction parameter of PLLA/MgO70-ODLA30 (5.459) has superior properties to those of PLLA/MgO70-OLLA30 (4.013) and PLLA/Mg(OH)2 (1.774). The cell cytotoxicity and acid-induced inflammatory response are suppressed by the neutralizing effect of the MgO-ODLAs. In addition, the inflammatory problem caused by the rapid acidification of the stereocomplex structure is also addressed. As a result, the stereocomplex structure of the MgO-ODLA/PLLA composite can be used to overcome the problems associated with the biomedical applications of PLLA films.

Incidence and classification of neointimal proliferation and in-stent restenosis in post-stenting patients at 1-year interval: findings from non-invasive coronary computed tomography angiography

OBJECTIVES

To evaluate the incidence of coronary in-stent restenosis (ISR) and neointimal proliferation by coronary CT angiography (CCTA) at 1-year follow-up in asymptomatic patients.

METHODS

234 patients (mean age: 67 ± 10.2 years, range 39-88 years, 180 males and 54 females) with 379 stents were prospectively enrolled in this study. Binary ISR was classified by CCTA into 4 types using Mehran classification. Neointimal proliferation was similarly classified into focal and diffuse types. All patients with CCTA-revealed ISR or neointimal proliferation underwent further invasive coronary angiography (ICA) for validation. Fisher's exact test was used for comparison.

RESULTS

ICA revealed patent stents with neointimal proliferation in 39 patients (16.7%, 39/234) and binary ISR in 23 patients (9.8%, 23/234). Lesion-based analysis showed 12 type I ISR lesions, 4 type II ISR lesions, 1 type III ISR lesion and 7 type IV ISR lesions. Among cases with neointimal proliferation, 27 lesions were classified as focal type whereas 13 lesions were classified as diffuse type. Patients with diabetes mellitus were associated with higher incidence of CCTA-revealed neointimal proliferation (21/77 vs. 18/157, p=0.002) as well as ISR (12/77 vs. 11/157, p=0.038), compared to patients without diabetes. CCTA was found to have good diagnostic performance for neointimal proliferation and ISR detection as well as classification, with an overall accuracy of 84.4% (54/64).

CONCLUSIONS

Silent ISR as well as neointimal proliferation is not uncommon findings in asymptomatic post-stenting patients at 1-year interval, as revealed by CCTA. Patients with diabetes are prone to have higher incidence of neointimal proliferation.

Concentration-dependent differential effects of udenafil on viability, proliferation, and apoptosis in vascular endothelial and smooth muscle cells

OBJECTIVES

Local strategies directed against vascular smooth muscle cell (VSMC) proliferation, such as drug-eluting stents (DES), reduce the occurrence of restenosis. However, these approaches may also inhibit vascular endothelial cell (VEC) proliferation and impair reendothelialization, and hence, increase susceptibility to late thrombosis. In this study we examined the differential effects of various concentrations of the type 5 phosphodiesterase (PDE-5) inhibitor, udenafil, on viability, proliferation, and apoptosis of VEC and VSMC, in order to identify the optimal concentration of udenafil that minimizes inhibition of VEC survival and growth, and maximizes inhibition of VSMC survival and growth.

MATERIALS AND METHODS

VEC from human umbilical veins and VSMC from human aorta were exposed to various concentrations of udenafil (1, 10, and 100 μmol/l and 1 mmol/l) for 24 h, and its effects on cell viability, proliferation, and apoptosis were studied using 5-bromo-2'- deoxyuridine (BrdU), methylthiazoletetrazolium (MTT) assay, trypan blue dye exclusion, and flow cytometry.

RESULTS

Udenafil inhibited the survival and growth of VEC and VSMC in a concentration-dependent manner over a range of concentrations. At 100 μmol/l, udenafil, inhibited VEC proliferation significantly less than VSMC proliferation (P < 0.05), and could significantly induce VEC apoptosis less than VSMC apoptosis (P < 0.05).

CONCLUSIONS

Udenafil has a differential effect on survival and growth in VEC and VSMC. The maximal differential effect, with minimal inhibition of VEC and maximal inhibition of VSMC, occurs at 100 μmol/l. This characteristic suggests that udenafil is a promising agent for use in DES.