Two-year angiographic and intravascular ultrasound follow-up after implantation of sirolimus-eluting stents in human coronary arteries

Recent advances in the design and immobilization of heparin for biomedical application: A review

Heparin, a member of the glycosaminoglycan family, is renowned as the most negatively charged biomolecule discovered within the realm of human biology. This polysaccharide serves a vital role as a regulator for various proteins, cells, and tissues within the human body, positioning itself as a pivotal macromolecule of significance. The domain of biology has witnessed substantial interest in the intricate design of heparin and its derivatives, particularly focusing on heparin-based polymers and hydrogels. This intrigue spans a wide spectrum of applications, encompassing diverse areas such as protein adsorption, anticoagulant properties, controlled drug release, development of implants, stent innovation, enhancement of blood compatibility, acceleration of wound healing, and pioneering strides in tissue engineering. This comprehensive overview delves into a multitude of developed heparin conjugates, employing various methods, and explores their functions in both the biomedicine and electronics fields. The efficacy of materials derived from heparin is also thoroughly investigated, encompassing considerations such as thrombogenicity, drug release kinetics, affinity for growth factors (GFs), biocompatibility, and electrochemical analyses. We firmly believe that by redirecting focus towards research and advancements in heparin-related polymers/hydrogels, this study will ignite further research and accelerate potential breakthroughs in this promising and evolving field of discovery.

Effects of switching from clopidogrel to prasugrel at the chronic phase after coronary stenting on antiplatelet action and vascular endothelial function: Switch-Pras study

Compared to clopidogrel, prasugrel has a lower incidence of ischemic events following percutaneous coronary intervention (PCI) because of an early reduction during the acute phase in P2Y12 reaction units (PRU). The objective of this study was to compare the antiplatelet effect and vascular endothelial function of both drugs during the chronic phase after PCI. Patients who had undergone PCI and were confirmed to have no restenosis by follow-up coronary angiography under dual anti-platelet therapy with clopidogrel (75 mg/day) and aspirin (100 mg/day) were randomized to either continue clopidogrel or switch to prasugrel (3.75 mg/day). At baseline, prior to randomization we determined the CYP2C19 genotype. At the baseline and 24 weeks after randomization, the P2Y12 reactivity unit (PRU) was measured using the VerifyNow™ P2Y12 assay. Endothelial function was evaluated by flow-mediated vasodilation (FMD) and reactive hyperemia peripheral arterial tonometry (RH-PAT), while and circulating CD34+/CD133+/CD45^low progenitor cells were measured by flow cytometric analysis. Serum high-sensitivity C-reactive protein (hsCRP) level was also measured. The PRU was reduced significantly in the prasugrel group (P = 0.0008), especially in patients who were intermediate or poor metabolizers based on the CYP2C19 genotype (P < 0.0001). This reduction was not observed in the clopidogrel group. The number of CD34+/CD133+/CD45^low cells increased in the clopidogrel group (P = 0.008), but not in the prasugrel group. The hsCRP, FMD and reactive hyperemia index measured by RH-PAT did not change in either group. Prasugrel is potentially better than clopidogrel for preventing thrombotic events, although clopidogrel may have an advantage over prasugrel in terms of preventing atherosclerotic events. Proper use of thienopyridine drugs based on the CYP2C19 genotype has promising clinical potential.

Acute Thrombus Burden on Coated Flow Diverters Assessed by High Frequency Optical Coherence Tomography

PURPOSE

The implantation of flow diverters requires administration of dual anti-platelet therapy, posing the potential for complications. The p48MW HPC (phenox, Bochüm, Germany) hydrophilic-coated flow diverting stent is designed to be anti-thrombotic, thus opening the potential for single anti-platelet therapy. We deploy a novel intravascular high-resolution imaging technique, high-frequency optical coherence tomography (HF-OCT), to study in an animal model the acute thrombus formation on coated p48MW devices versus uncoated control devices.

METHODS

Three pigs were implanted with 4 flow diverters each, two test hydrophilic-coated devices, and two control uncoated devices (p48MW). Each pig was treated with a different anti-platelet regime: no anti-platelet therapy, aspirin only, aspirin and clopidogrel. Twenty minutes after the flow diverter was implanted, an HF-OCT data set was acquired. Acute clot formed on the flow diverter at each covered side branch was measured from the HF-OCT slices. Factors considered to be important were the device type (pHPC versus bare metal), aspirin, clopidogrel, and vessel location. A linear model was constructed from the significant factors.

RESULTS

Both coating (p < 0.001) and aspirin (p = 0.003) were significantly related to reduction in clot burden, leading to an approximate 100-fold and 50-fold reduction in clot, respectively.

CONCLUSIONS

This study shows the power of HF-OCT not only in the detection of clot but also the quantification of clot burden. In an animal model, the pHPC-coated p48MW significantly reduced acute thrombus formation over jailed side branches as compared to the bare metal p48MW that was nearly eliminated when combined with aspirin administration.

In vivo canine study of three different coatings applied to p64 flow-diverter stents: initial biocompatibility study

Background

Flow-diverter stents (FDSs) have revolutionised the treatment of intracranial aneurysms. However, associated dual antiplatelet treatment is mandatory. We investigated the biocompatibility of three proprietary antithrombogenic coatings applied to FDSs.

Methods

After Institutional Animal Care and Use Committee approval, four domestic juvenile female dogs (weight 19.9 ± 0.9 kg, mean ± standard deviation) were commenced on three different oral antiplatelet regimes: no medication (n = 1), acetylsalicylic acid (n = 2), and acetylsalicylic acid and clopidogrel (n = 1). Four p64 FDSs were randomly implanted into the subclavian, common carotid, and external carotid arteries of each dog, including both uncoated p64 stents and p64 stents coated with three different antithrombogenic hydrophilic coating (HPC). Angiography and histological examinations were performed. Wilcoxon/Kruskal-Wallis and ANOVA were used with p value < 0.05 considered as significant.

Results

Minimal inflammatory cell infiltration and no device-associated granulomatous cell inflammation were observed. No significant difference in adventitial inflammation (p = 0.522) or neointimal/medial inflammation (p = 0.384) between coated and uncoated stents as well as between the different stent groups regarding endothelial cell loss, surface fibrin/platelet deposition, medial smooth muscle cell loss, or adventitial fibrosis were found. Acute self-limiting thrombus formed on 6/16 implants (37.5%), and all of the thrombi were noted on devices implanted in the common or external carotid artery irrespective of the surface coating. Two of 12 p64 HPC-coated stents (16.7%) and 1/4 uncoated p64 stents (25%) showed severe or complete stenosis at delayed angiography.

Conclusions

In these preliminary in vivo experiments, HPC-coated p64 FDSs appeared to be biocompatible, without acute inflammation.

Flexible Coils with a Drug-Releasing Hydrophilic Coating: A New Platform for Controlled Delivery of Drugs to the Eye?

Delivery of drugs to the front-side of the eye is routinely done through eye drops. It is known that approximately 80% of each eye-drop is lost, as a result of rapid clearance of the tear fluid via the naso-lacrymal canal. Consequently, repeated administration through several droplets is usually necessary to achieve a desired effect, such as widening of the pupil prior to corneal surgery. A new ocular drug delivery device was studied. The new device is believed to provide a basis for a more convenient and efficient method for ocular drug delivery. The device is a metallic coil with a hydrophilic, drug-containing polymeric coating. The coil is placed in the conjuctival fornix (under the lower eye-lid) and the drug is slowly released by diffusion into the tear fluid. The capacity of the device could be increased by using the lumen of the coils as a depot for the drug to be released. Preliminary experiments with the new device were performed largely in vitro and in vivo. The latter experiments involved the release of a fluorescent dye and atropine (a potent mydriatic agent) in the eye of several healthy volunteers. The first results obtained with the new device indicate its potential utility. More research and development work is required to define the optimal design of the coil in order to minimize the risk of irritation. Furthermore, the parameters that define the kinetics of the intraocular drug release must be defined and optimized with respect to the exact application.

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.

Comparative analysis between 64- and 320-slice spiral computed tomography in the display of coronary artery stents and diagnosis of in-stent restenosis

The aim of the present study was to compare the accuracy of 64-multi-slice spiral computed tomography (64-MSCT) and 320-MSCT in the display of coronary artery stents and diagnosis of in-stent restenosis. The data collected from the 64- and 320-MSCT coronary angiography of 93 patients following coronary artery stent implantation were retrospectively analyzed. The 64-MSCT group comprised 30 cases with 57 stents and the 320-MSCT group comprised 63 cases with 93 stents. The image quality, heart rate of the patients and the radiation effective dose (ED) they were subjected to, were compared. Furthermore, the diagnostic abilities of 64-and 320-MSCT coronary angiography for in-stent restenosis were evaluated using invasive coronary angiography results as the gold standards. Statistically significant differences were observed in the heart rate and ED of the patients from the two groups (P<0.05), but no significant difference was identified in the accuracy index (P>0.05). The sensitivity, specificity, positive and negative predictive value and accuracy of the 64-MSCT group were found to be 100% (7/7), 93.94% (31/33), 77.78% (7/9), 100% (31/31) and 95% (38/40), respectively, and those in the 320-MSCT group were found to be 100% (16/16), 95.89% (70/73), 84.21% (16/19), 100% (70/70) and 96.63% (86/89), respectively. The present findings suggest that both 64-MSCT and 320-MSCT can be used for follow-up and curative effect evaluation following coronary stent implantation; however, 320-MSCT has fewer requirements of the patients' heart rate and uses a lower radiation dose.

A New Hemodynamic Ex Vivo Model for Medical Devices Assessment

BACKGROUND

In-stent restenosis (ISR) remains a major public health concern associated with an increased morbidity, mortality, and health-related costs. Drug-eluting stents (DES) have reduced ISR, but generate healing-related issues or hypersensitivity reactions, leading to an increased risk of late acute stent thrombosis. Assessments of new DES are based on animal models or in vitro release systems, which have several limitations. The role of flow and shear stress on endothelial cell and ISR has also been emphasized. The aim of this work was to design and first evaluate an original bioreactor, replicating ex vivo hemodynamic and biological conditions similar to human conditions, to further evaluate new DES.

METHODS

This bioreactor was designed to study up to 6 stented arteries connected in bypass, immersed in a culture box, in which circulated a physiological systolo-diastolic resistive flow. Two centrifugal pumps drove the flow. The main pump generated pulsating flows by modulation of rotation velocity, and the second pump worked at constant rotation velocity, ensuring the counter pressure levels and backflows. The flow rate, the velocity profile, the arterial pressure, and the resistance of the flow were adjustable. The bioreactor was placed in an incubator to reproduce a biological environment.

RESULTS

A first feasibility experience was performed over a 24-day period. Three rat aortic thoracic arteries were placed into the bioreactor, immersed in cell culture medium changed every 3 days, and with a circulating systolic and diastolic flux during the entire experimentation. There was no infection and no leak. At the end of the experimentation, a morphometric analysis was performed confirming the viability of the arteries.

CONCLUSIONS

We designed and patented an original hemodynamic ex vivo model to further study new DES, as well as a wide range of vascular diseases and medical devices. This bioreactor will allow characterization of the velocity field and drug transfers within a stented artery with new functionalized DES, with experimental means not available in vivo. Another major benefit will be the reduction of animal experimentation and the opportunity to test new DES or other vascular therapeutics in human tissues (human infrapopliteal or coronary arteries collected during human donation).

Controlling drug delivery from coronary stents: are we aiming for the right targets?

In this review article, the currently employed or explored delivery concepts for local intravascular drug delivery with drug-eluting stents (DES) are discussed with a special emphasis on clinical evidence regarding the desired release profiles. Traditional concepts to control drug release from DES include diffusion through polymers, polymer degradation and erosion as well as dissolution of particulate drug. Published clinical studies do not always reveal fine mechanistic details. The long duration of release favored for DES and the short duration of release favored for drug-eluting balloons require further investigation in experimental studies and clinical trials.

Accelerated Recovery of Endothelium Function after Stent Implantation with the Use of a Novel Systemic Nanoparticle Curcumin

Curcumin was reported to exhibit a wide range of pharmacological effects including antioxidant, anti-inflammatory, and antiproliferative activities and significantly prevent smooth muscle cells migration. In the present study, a novel kind of curcumin loaded nanoparticles (Cur-NP) has been prepared and characterized with the aim of inhibiting inflammation formation and accelerating the healing process of the stented arteries. Cur-NP was administrated intravenously after stent implantation twice a week and detailed tissue responses were evaluated. The results demonstrated that intravenous administration of Cur-NP after stent implantation accelerated endothelial cells restoration and endothelium function recovery and may potentially be an effective therapeutic alternative to reduce adverse events for currently available drug eluting stents.

Anti-CD133 antibody immobilized on the surface of stents enhances endothelialization

Drug eluting stents successfully reduce restenosis at the cost of delayed reendothelialization. In recent years, a novel concept to enhance reendothelialization using anti-CD34 antibody coated stents which capture circulating progenitor cells (EPCs) has been developed with conflicting clinical results. CD133 is a glycoprotein expressed on circulating hematopoietic and putative endothelial-regenerating cells and may be superior to CD34 for EPCs capture stents. In the present study, anti-CD133 antibody has been successfully immobilized to the biodegradable polymeric coating material by covalent conjugation. We explore whether anti-CD133 antibody coated stents (CD133 stents) might accelerate reendothelialization in comparison with bare metal stents (BMS) through the superior ability to capture EPCs. The in vitro cell culture results indicate that anti-CD133 antibody functionalized polymer film significantly promotes CD133 positive cells attachment and growth compared with the unfunctionalized polymer film. In the semi-in vivo arteriovenous shunt model CD133 stents demonstrate much quicker specific capturing of EPCs from the blood stream than BMS within 6 hours. In a porcine coronary artery injury model CD133 stents show more effective reendothelialization in short term compared with BMS, while no significant difference in endothelial function recovery was observed between these two groups within 6-month followup.

Regulation of smooth muscle cells in development and vascular disease: current therapeutic strategies

Vascular smooth muscle cells (SMCs) exhibit extensive phenotypic diversity and rapid growth during embryonic development, but maintain a quiescent, differentiated state in adult. The pathogenesis of vascular proliferative diseases involves the proliferation and migration of medial vascular SMCs into the vessel intima, possibly reinstating their embryonic gene expression programs. Multiple mitogenic stimuli induce vascular SMC proliferation through cell cycle progression. Therapeutic strategies targeting cell cycle progression and mitogenic stimuli have been developed and evaluated in animal models of atherosclerosis and vascular injury, and several clinical studies. Recent discoveries on the recruitment of vascular progenitor cells to the sites of vascular injury suggest new therapeutic potentials of progenitor cell-based therapies to accelerate re-endothelialization and prevent engraftment of SMC-lineage progenitor cells. Owing to the complex and multifactorial nature of SMC regulation, combinatorial antiproliferative approaches are likely to be used in the future in order to achieve maximal efficacy and reduce toxicity.

Drug-eluting stents: from evidence to policy

Drug-eluting stents are a major breakthrough in cardiology, with the Cypher (Cordis Corporation) and Taxus (Boston Scientific) stents preventing 60-70% of repeat coronary revascularizations, compared with bare metal stents. Both evidence- and risk-based application of drug-eluting stents is expected to create relevant financial and equity problems to most public hospitals, as the cost of drug-eluting stents is over 1000 higher than traditional stents. In the perspective of third-party payers, drug-eluting stents are cost-effective revascularization strategies for a large portion of patients actually undergoing stenting. However, adequate guidelines and reimbursement strategies are still awaited in several countries.

Fabrication of nonbiofouling metal stent and in vitro studies on its hemocompatibility

In recent years, there has been increasing interest for the surface modification of biomaterials in order to improve their surface properties. The bare metal stents surface based on 3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate polymers has shown an excellent antifouling and blood compatibility by using surface-initiated atom transfer radical polymerization. Surface structure, morphology, wettability, and element content were characterized by scanning electronic microscope, static water contact angles measurement, X-ray photoelectron spectroscopy measurement, respectively. The results showed zwitterionic brushes were successfully fabricated on bare metal stents. The blood compatibility of bare metal stents before and after modification was evaluated by platelet adhesion tests, hemolysis assay, morphological changes of red blood cells, coagulation time tests, plasma recalcification time assay, complement activation, and platelet activation at molecular level. Moreover, the cytotoxicity was also to be characterized. All assays showed after the modification with zwitterionic brush the metal stents displayed a property of excellent blood compatibility and low cytotoxicity.

Optical coherence tomography versus intravascular ultrasound to evaluate coronary artery disease and percutaneous coronary intervention

OBJECTIVES

We compared intravascular ultrasound (IVUS) and 2 different generations of optical coherence tomography (OCT)-time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT)-for the assessment of coronary disease and percutaneous coronary intervention (PCI) using stents.

BACKGROUND

OCT is a promising light-based intravascular imaging modality with higher resolution than IVUS. However, the paucity of data on OCT image quantification has limited its application in clinical practice.

METHODS

A total of 227 matched OCT and IVUS pull backs were studied. One hundred FD-OCT and IVUS pull backs in nonstented (n = 56) and stented (n = 44) vessels were compared. Additionally, 127 matched TD-OCT and IVUS images were compared in stented vessels.

RESULTS

FD-OCT depicted more severe native coronary disease than IVUS; minimal lumen area (MLA) was 2.33 ± 1.56 mm(2) versus 3.32 ± 1.92 mm(2), respectively (p < 0.001). Reference vessel dimensions were equivalent between FD-OCT and IVUS in both native and stented coronaries, but TD-OCT detected smaller reference lumen size compared with IVUS. Immediately post-PCI, in-stent MLAs were similar between FD-OCT and IVUS, but at follow-up, both FD-OCT and TD-OCT detected smaller MLAs than did IVUS, likely due to better detection of neointimal hyperplasia (NIH). Post-PCI malapposition and tissue prolapse were more frequently identified by FD-OCT.

CONCLUSIONS

FD-OCT generates similar reference lumen dimensions but higher degrees of disease severity and NIH, as well as better detection of malapposition and tissue prolapse compared with IVUS. First-generation TD-OCT was associated with smaller reference vessel dimensions compared with IVUS.

Comparison of vascular response to the everolimus-eluting stent versus the paclitaxel-eluting stent: intravascular ultrasound results from the SPIRIT III trial

AIMS

The purpose of this study was to investigate the vascular response of the everolimus-eluting stent (EES) compared with the paclitaxel-eluting stent (PES) using serial intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the SPIRIT III trial, a multicentre, 2:1 randomised, controlled study comparing EES and PES in de novo native coronary artery lesions. IVUS images were eligible for volumetric analysis at eight-month follow-up in 158 lesions (EES: 113, PES: 45). At eight months, EES had a smaller neointimal volume index (VI: mm3/mm) (EES: 0.4±0.4 vs. PES: 0.8±0.8 mm3/mm, p=0.002) and also a smaller % neointimal obstruction (EES: 7.1±6.7% vs. PES: 11.1±10.5%, p=0.005) compared with PES. While there was no significant change in vessel VI with EES, there was a significant increase in vessel VI in PES during eight-month follow-up (EES: 0.1±1.2 vs. PES: 1.2±0.8 mm3/mm, p=0.001). There were no statistical differences in the frequency of edge dissection or incomplete stent apposition between the two groups.

CONCLUSIONS

Detailed IVUS analysis confirmed significantly less neointimal hyperplasia with EES compared with PES. While there was no increase in vessel volume with EES during the eight-month follow-up period, vessel enlargement was seen at the stented segment in PES.

Anti-inflammatory effects of arsenic trioxide eluting stents in a porcine coronary model

Previous research from our group has demonstrated arsenic trioxide eluting stents significantly reduced neointimal area and thickness compared with bare metal stents. In the present study, the anti-inflammatory effects of arsenic trioxide in vitro and arsenic trioxide eluting stents in a porcine coronary model have been explored. Sixty-five pigs underwent placement of 139 oversized stents in the coronary arteries with histologic analysis, endothelial function analysis, and immunohistochemical and western blot analyses. Arsenic trioxide eluting stents effectively inhibited local inflammatory reactions, while no significant difference in endothelialization and endothelial function between arsenic trioxide eluting stents and bare metal stents was observed. Arsenic trioxide eluting stents favorably modulate neointimal formation due to less augmentation of early inflammatory reactions, and quick endothelialization of the stent surface, which might contribute to long-term safety and efficacy of drug eluting stents.

Two-year results of a durable polymer everolimus-eluting stent in de novo coronary artery stenosis (The SPIRIT FIRST Trial)

AIMS

The successful use of everolimus on a durable polymer was earlier reported with 6 and 12 months data from this first-in-man study. This reports the long-term follow-up of the XIENCE V everolimus-eluting stent.

METHODS AND RESULTS

This prospective, single-blinded, randomised, multicentre clinical trial evaluated the safety and efficacy of the XIENCE V everolimus-eluting coronary stent system versus an identical bare metal stent in the treatment of patients with a single de novo coronary artery stenosis of >/=50% and <100% and a vessel diameter of 3.0 mm as assessed by on-line quantitative coronary angiography that could be covered by a single 18 mm stent.Sixty patients were randomised and at two-year follow-up, clinical data was available in 96% and 97% of patients in the everolimus and control arm, respectively. Four patients were excluded due to protocol violations and two patients withdrew consent.In the everolimus arm no additional death, myocardial infarction, clinically driven TLR, or TVR events were observed between one and two-year follow-up. The 2-year hierarchical MACE rate for the everolimus arm remained 15.4% (4/26). In the control group, two patients had a clinically driven target lesion revascularisation. MACE rate increased from 21.4% (6/28) to 25.0% (7/28) in the control group.

CONCLUSIONS

This report confirms and extends the safety and efficacy results of the durable polymer XIENCE V everolimus-eluting stent up to two years as compared to identical bare metal stents.

Evaluation of long-term follow-up with neointimal coverage and stent apposition after sirolimus-eluting stent implantation by optical coherence tomography

BACKGROUND

Late stent thrombosis related to delayed endothelialization is a major concern after drug-eluting stent (DES) implantation. The long-term vascular response towards DES implantation remains unclear. Optical coherence tomography (OCT) is a high-resolution imaging modality which provides new opportunities for evaluating neointimal coverage and stent strut apposition after stent implantation.

METHODS

Fifty two patients who accepted 64 sirolimus-eluting stents (SESs, Cypher Select) were enrolled in the study. The OCT procedure was performed in 20 patients at 12 months (group 1), 17 patients at 24 months (group 2), and 15 patients at 48 months (group 3) after SESs implantation, respectively. The neointimal hyperplasia (NIH) thickness and stent strut apposition were assessed at 1-mm interval, and the presence of thrombus was observed in each stent.

RESULTS

The NIH thickness was significantly higher at 48 months than that of 12 months (0.1694 ± 0.1455 mm in G3 vs. 0.1455 ± 0.1373 mm in G1, P < 0.01) and 24 months (0.1514 ± 0.1296 mm in G2, P <0.01) after SESs implantation, but no significant difference existed between that of 12 months and 24 months (P > 0.05). Longer follow-up time was associated with significant decrease in the prevalence of uncovered struts (17.3% in group 1 vs. 8.8% in group 2 vs. 2.6% in group 3, P < 0.01) and malapposed struts (14.2% in group 1 vs. 10.3% in group 2 vs. 4.7% in group 3, P < 0.01). The incidence of intracoronary thrombus steadily decreased from 3.6% at 12 months to 2.4% at 24 months, and to 0.8% at 48 months (P < 0.01).

CONCLUSION

Neointimal growth continued for as long as 48 months after SES implantation. NIH thickness increased insignificantly from 12 to 24 months, but markedly increased at 48 months after stent implantation. Late neointimal growth was accompanied by a higher rate of covered struts and lower rate of malapposed stent struts.

Serial angiographic findings and prognosis of stent fracture site without early restenosis after sirolimus-eluting stent implantation

BACKGROUND

Stent fracture is one of the possible causes of in-stent restenosis after sirolimus-eluting stent (SES) implantation. However, long-term prognosis including late restenosis in stent fracture site without early restenosis remains unknown. The aim of this study is to investigate the risk of late restenosis at the stent fracture site without early restenosis after SES implantation.

METHODS

We divided 366 patients with 490 lesions into 2 groups with or without stent fracture based on the first scheduled follow-up coronary angiography (fracture group, 21 lesions; nonfracture group, 469 lesions). The second scheduled follow-up coronary angiography (>15 months after SES implantation) was performed in 83 patients with 124 lesions.

RESULTS

Target lesion revascularization due to late restenosis at the stent fracture site did not occur in the fracture group, but occurred in 5 lesions in the nonfracture group. At the first follow-up, minimal luminal diameter was significantly smaller and percentage diameter stenosis was significantly larger in the fracture group (1.98 ± 0.41 vs 2.52 ± 0.49 mm, P = .001 and 30.5% ± 13.1% vs 13.0% ± 8.8%, P < .0001, respectively). These differences were also present at the second follow-up (P = .01 and P = .007, respectively). In each group, there were no significant changes in minimal luminal diameter, percentage diameter stenosis, and late lumen loss between the first and second follow-up.

CONCLUSIONS

Late restenosis was not observed in stent fracture sites without early restenosis during the midterm follow-up after SES implantation.

Comparison of vascular response to zotarolimus-eluting stent vs paclitaxel-eluting stent implantation: pooled IVUS results from the ZoMaxx I and II trials

BACKGROUND

The ZoMaxx I and II trials were randomized controlled studies of the zotarolimus-eluting, phosphorylcholine-coated, TriMaxx stent for the treatment of de novo coronary lesions. The aim of this study was to compare the vessel response between zotarolimus- (ZES) and paclitaxel-eluting stents (PES) using intravascular ultrasound (IVUS).

METHODS AND RESULTS

Data were obtained from the ZoMaxx I and II trials, in which a standard IVUS parameter was available in 263 cases (baseline and 9-months follow up). Neointima-free frame ratio was calculated as the number of frames without IVUS-detectable neointima divided by the total number of frames within the stent. While an increase in vessel and plaque was observed in PES from baseline to follow up, there was no significant change in ZES. At follow up, % neointimal obstruction was significantly higher (15.4 ± 8.8% vs 11.3 ± 9.7%), and minimum lumen area at follow up was significantly smaller in ZES compared to PES. However, the incidence of IVUS-defined restenosis (maximum cross-sectional narrowing >60%) was similar in the 2 groups (3.2% vs 6.7%). Neointima-free frame ratio was significantly lower in ZES. There were 5 cases of late incomplete stent apposition in PES and none in ZES.

CONCLUSIONS

These IVUS results demonstrate a similar incidence of severe narrowing between these 2 DES. There was a moderate increase in neointimal hyperplasia that was associated with a greater extent of neointimal coverage in ZES compared with PES.

Five-year long-term clinical follow-up of the XIENCE V everolimus eluting coronary stent system in the treatment of patients with de novo coronary artery lesions: the SPIRIT FIRST trial

BACKGROUND

Drug-eluting stents have shown to be superior over bare metal stents in clinical and angiographic outcomes after percutaneous treatment of coronary artery stenosis. However, long-term follow-up data are scarce and only available for sirolimus- and paclitaxel-eluting stents.

AIM

To assess the feasibility and performance of the XIENCE V everolimus-eluting stent (EES) versus an identical bare metal stent after a 5-year follow-up period.

METHODS

SPIRIT FIRST was a First in Man, multicentre, prospective, single-blind, clinical trial, randomizing 60 patients with a single de novo coronary artery lesion in a ratio of 1:1 to either an everolimus eluting or a bare metal control stent.

RESULTS

At 5-year clinical follow-up, data were available in 89% and 86% of patients in the everolimus and control arm, respectively. In the everolimus arm, no additional death, myocardial infarction, clinically driven target lesion revascularization (TLR), or clinically driven target vessel revascularization (TVR) events were observed between 1- and 5-year follow-up. The 5-year hierarchical major adverse cardiac events (MACE) and target vessel failure (TVF) rates for the everolimus arm were 16.7% (4/24) for both endpoints. In the control group, no additional cardiac death, myocardial infarction, or clinically driven TLR events were observed between 2- and 5-year follow-up. No additional clinically driven TVR events were observed between 3- and 5-year follow-up. The 5-year hierarchical MACE and TVF rates for the control arm were 28.0% (7/25) and 36.0% (9/25), respectively. No stent thromboses were observed in either the everolimus arm or the control arm up to 5 years.

CONCLUSION

The favorable 5-year long term clinical outcome of the EES is consistent with the results from other studies of the EES with shorter follow-up.

Long-term vascular changes after drug-eluting stent implantation assessed by serial volumetric intravascular ultrasound analysis

Using serial volumetric intravascular ultrasonography, we evaluated the predictors of late intimal hyperplasia (IH) increases after drug-eluting stent implantation. All eligible patients who underwent 6-month angiography without visual restenosis were requested to undergo a 2-year follow-up examination. Complete serial (after stenting and early [6-month], and late [2-year] follow-up) angiographic and intravascular ultrasound data were available for 135 patients with 143 lesions: 99 sirolimus-eluting stents and 44 paclitaxel-eluting stents. The external elastic membrane, stent, lumen, and peri-stent plaque volumes (external elastic membrane minus stent) were normalized by stent length. The percentage of IH volume was calculated as IH volume/stent volume x 100. The early reduction in the minimum lumen area was greater than the late reduction in the minimum lumen area (-0.8 +/- 0.8 vs -0.2 +/- 0.5 mm(2), p <0.001). A progressive increase occurred in the percentage of IH volume: 8.1 +/- 7.1% from baseline to 6 months and 2.4 +/- 3.9% from 6 months to 2 years (p <0.001, between the early and late increases in the percentage of IH). The use of paclitaxel-eluting stents was the only independent predictor for the percentage of IH volume at 6 months (beta = 0.419, p <0.001). The use of paclitaxel-eluting stents (beta = 0.365, p <0.001, 95% confidence interval 3.7 to 9.7) and the post-stenting normalized plaque and media volume (beta = 0.195, p = 0.020, 95% confidence interval 0.1 to 1.6) were the only independent predictors for the percentage of IH volume at 2 years. However, when the percentage of IH at 6 months was forced into the model, the percentage of IH at 6 months and the post-stenting normalized plaque and media volume, not paclitaxel-eluting stent use, predicted the 2-year percentage of IH. In conclusion, although IH continued to increase beyond 6 months, the growth rate of intima and luminal loss attenuated with time.

The anesthesia patient with acute coronary syndrome

This article reviews the current state of knowledge of the pathophysiology, diagnosis, and treatment of acute coronary syndrome outside and during the perioperative period. It highlights some aspects of relevance for the anesthesiologist caring for these patients. Perioperative modalities for the management of patients suffering from this syndrome, the major guidelines and the evidence behind them, and possible avenues for future research is explored.

Intracoronary optical coherence tomography: a comprehensive review clinical and research applications

Cardiovascular optical coherence tomography (OCT) is a catheter-based invasive imaging system. Using light rather than ultrasound, OCT produces high-resolution in vivo images of coronary arteries and deployed stents. This comprehensive review will assist practicing interventional cardiologists in understanding the technical aspects of OCT based upon the physics of light and will also highlight the emerging research and clinical applications of OCT. Semi-automated imaging analyses of OCT systems permit accurate measurements of luminal architecture and provide insights regarding stent apposition, overlap, neointimal thickening, and, in the case of bioabsorbable stents, information regarding the time course of stent dissolution. The advantages and limitations of this new imaging modality will be discussed with emphasis on key physical and technical aspects of intracoronary image acquisition, current applications, definitions, pitfalls, and future directions.

c-Jun regulates shear- and injury-inducible Egr-1 expression, vein graft stenosis after autologous end-to-side transplantation in rabbits, and intimal hyperplasia in human saphenous veins

Coronary artery bypass graft failure represents an unsolved problem in interventional cardiology and heart surgery. Late occlusion of autologous saphenous vein bypass grafts is a consequence of neointima formation underpinned by smooth muscle cell (SMC) migration and proliferation. Poor long term patency and the lack of pharmacologic agents that prevent graft failure necessitate effective alternative therapies. Our objective here was to evaluate the effect of targeted inhibition of the bZIP transcription factor c-Jun on intimal hyperplasia in human saphenous veins and vein graft stenosis after autologous end-to-side transplantation. DNAzymes targeting c-Jun attenuated intimal hyperplasia in human saphenous vein explants. Adenovirus-forced c-Jun expression stimulated SMC proliferation, proliferating cell nuclear antigen, and MMP-2 expression. c-Jun DNAzymes abrogated Adeno-c-Jun-inducible SMC growth and wound repair and reduced intimal thickening in jugular veins of New Zealand white rabbits 4 weeks after autologous end-to-side transplantation to carotid arteries. Conversely, in a DNAzyme-free setting, Adeno-c-Jun potentiated neointima formation in the veins compared with Adeno-LacZ. Inducible c-Jun expression is ERK1/2- and JNK-dependent but p38-independent. Injury- and shear-inducible c-Jun controls early growth response-1. These data demonstrate that strategies targeting c-Jun may be useful for the prevention of vein graft stenosis. Control of one important shear-responsive transcription factor by another indicates the existence of transcriptional amplification mechanisms that magnify the vascular response to cell injury or stress through inducible transcriptional networks.

Nitric oxide synthase gene therapy: progress and prospects

NOS gene therapy has been the focus of extensive research as dysfunction of this enzyme has been implicated in several cardiovascular diseases. Research has concentrated on comparing the effect of gene delivery of NOS isoforms (eNOS, iNOS and nNOS) in healthy and diseased animal models on intimal hyperplasia, restenosis, vascular tone and ischemia-reperfusion injury. Most results demonstrate therapeutic benefits following vascular gene delivery of all NOS in pre-clinical models of cardiovascular disease. eNOS has been shown to have particular promise as it promotes re-endothelialisation and inhibits intimal hyperplasia in injured blood vessels. The ultimate goal is to translate the benefit of NOS gene therapy in animal models into clinical practise. To develop NOS gene therapy for clinical use further work needs to be undertaken to improve delivery systems and vectors to minimise detrimental side-effects and enhance positive treatment outcomes. This review focuses on current research on NOS gene therapy in cardiovascular disease and identifies the next steps that would be necessary to lead to clinical trials.

Drug-eluting stents: a comprehensive appraisal

Cardiovascular medicine has evolved over the last few decades, with the advent of percutaneous interventional treatments. In particular, balloon angioplasty and, subsequently, coronary stenting has revolutionized our current perspective of stable and unstable coronary artery disease management. However, the long-term results of stent usage have been blighted by the dual problems of in-stent restenosis and stent thrombosis. Whilst stent thrombosis became much less frequent with the introduction of dual-antiplatelet therapy, restenosis remained a significant problem. Intense work on stent development has successfully led to the introduction of drug-eluting stents (DES) in an effort to address this problem. Randomized trials have consistently proven the superior efficacy of DES over bare metal stents, in elective patients, acute coronary syndromes and patients with diabetes mellitus. Nevertheless, the routine use of DES in by-pass venous graft disease remains debatable. The initial DES used sirolimus and paclitaxel are now being joined by newer stents releasing drugs, such as everolimus, zotarolimus and tacrolimus. Ongoing developments with the stent platform and the polymer coating are also gradually improving the performance of these stents in clinical practice. More recently, the idea of antibody-coated stents that would encourage epithelialization of stent struts by endothelial progenitor cells recruitment has gained attraction among interventionists, with a possible beneficial impact on reducing the incidence of restenosis.

Coronary artery stents: Part I. Evolution of percutaneous coronary intervention

The subspecialty of interventional cardiology has made significant progress in the management of coronary artery disease over the past three decades with the development of percutaneous coronary transluminal angioplasty, atherectomy, and bare-metal and drug-eluting stents (DES). Bare-metal stents (BMS) maintain vessel lumen diameter by acting as a scaffold and prevent collapse incurred by angioplasty. However, these devices cause neointimal hyperplasia leading to in-stent restenosis and requiring reintervention in more than 20% of patients by 6 mo. DES (sirolimus and paclitaxel) prevent restenosis by inhibiting neointimal hyperplasia. However, DESs also delay endothelialization, causing the stents to remain thrombogenic for an extended, yet unknown, period of time. Late stent thrombosis is associated with a 45% mortality rate. Premature discontinuation of antiplatelet therapy, particularly clopidogrel, is the strongest predictor of stent thrombosis. Sixty percent of patients receive stents for off-label (unapproved) indications, which also increases the frequency of stent thrombosis. Clopidogrel and aspirin are the cornerstone of therapy in the prevention of stent thrombosis in both BMS and DES. Recommendations pertaining to the optimal duration of dual-antiplatelet therapy have been debated. Both the Food and Drug Administration and the American Heart Association/American College of Cardiologists, in association with other major societies, have made recommendations to extend the duration of dual-antiplatelet therapy in patients with DES to 1 yr. The 6-wk duration of dual-antiplatelet therapy in patients with BMS remains unchanged. All patients with coronary stents must remain on life-long aspirin monotherapy. Since the introduction of percutaneous transluminal coronary angioplasty for the treatment of coronary atherosclerosis, the practice of percutaneous coronary intervention has undergone a dramatic transformation from simple balloon dilation catheters to sophisticated mechanical endoprostheses. These advancements have impacted the practice of perioperative medicine. In this series of two articles, in Part I we will review the evolution of percutaneous coronary intervention and discuss the issues associated with percutaneous transluminal coronary angioplasty and coronary stenting; in Part II we will discuss perioperative issues and management strategies of coronary stents during noncardiac surgery.