Tacrolimus-eluting carbon-coated stents versus sirolimus-eluting stents for prevention of symptom-driven clinical end points

Safety and Efficacy of Modern Stents in Patients with Metabolic Syndrome

The impact of metabolic syndrome (MS) on stent performance and outcomes of patients underwent percutaneous coronary intervention (PCI), including stent implantation, had not yet been fully established. The aim of the present study was to investigate long-term safety and efficacy of 2nd generation DES vs. other stent types in MS patients underwent successful PCI for an acute coronary event. Descriptive epidemiology, angiographic characteristics and one-year clinical outcomes, including major adverse cardiovascular events (MACE) and target lesion revascularization (TLR) procedures were evaluated according to the stent type inserted for 204 patients. The occurrence of TLR (6.62% vs. 9.43%, p = 0.50) and the composite outcomes (20.52% vs. 24.52%, p = 0.54) did not differ significantly between patients having 2nd generation drug eluting stents (DES) or other stent types implanted at the index procedure. It seems that the PCI in acute coronary syndrome (ACS) is similarly efficient regardless of the stent type, suggesting that for the treatment of ACS in MS patients, all stent types show similar results, in terms of TLR or MACE.

Reduced histologic neo in-stent restenosis after use of a paclitaxel-coated cutting balloon in porcine coronary arteries

The incidence of in-stent restenosis (ISR) has declined dramatically, but once it develops, no current treatment option, such as drug-eluting stents, drug-coated balloons, or cutting balloons (CBs), prevents re-narrowing of the stented atherosclerotic artery. In this preclinical study, we aimed to improve the efficacy of ISR treatment by coating CBs with paclitaxel (paclitaxel-eluting cutting balloon; PECB) and to characterize the histological features of neo-ISRs that arise after ISR treatment. ISR was induced by bare metal stent (BMS) implantation in coronary arteries in pigs. After one month of follow-up, the BMS-induced ISR was treated with either CB or PECB. After another month, we performed quantitative coronary angiography, explanted the treated arteries and assessed histopathological and histomorphometric parameters. In addition, we compared the histological features of neo-ISRs with pre-treatment ISRs. Injury, inflammation, fibrin deposition, and endothelialization scores were similar between the CB and PECB groups at one month after ISR treatment. Neointimal area (0.87±0.61 vs. 1.95±1.14 mm², p=0.02), mean neointimal thickness (0.40±0.39 vs. 0.99±0.56 mm, p=0.01), and percent area stenosis (27.3±20.4 vs. 48.3±22.9%, p=0.04) were decreased in PECB-treated coronary arteries compared to CB-treated arteries, respectively. Density of cells (predominantly smooth muscle cells; SMCs) was increased in neo-ISRs (3.51±3.05×10³ vs. 6.35±2.57×10³ cells/mm², p<0.01), but significantly more CD68⁺ and CD20⁺ cells were found in the pre-treatment ISRs. In conclusion, PECB treatment of ISRs led to better results in terms of smaller neointimal area and %area stenosis of the neo-ISR. SMC density was increased in neo-ISRs in contrast with higher percentage of CD68⁺ and CD20⁺ cells in pre-treatment ISRs.

Association between the rs342293 polymorphism and adverse cardiac events in patients undergoing percutaneous coronary intervention

The single nucleotide polymorphism (SNP) rs342293 has been shown to influence platelet number and mean platelet volume (MPV). We investigated the association between the rs342293 polymorphism and cardiovascular outcome in a prospective cohort study. The rs342293 polymorphism was analysed in 404 patients with coronary artery disease undergoing percutaneous coronary intervention. The rates of cardiac adverse events were recorded during two years of follow-up. The polymorphism was associated with MPV (median 10.1 fL, interquartile range [IQR]: 9.6 to 10.6 in patients with the CC-allele vs 10.4 fL, IQR: 9.9 to 11.1 in G>C SNP carriers; p<0.001), but not with platelet count. Survival analysis indicated that carriers of the rs342293 G variant had a substantially higher risk to develop cardiac adverse events compared with wild type carriers during two years of follow-up (33% vs 22%; adjusted hazard ratio = 1.63, 95% confidence interval = 1.06–2.52, p=0.027). The rs342293 SNP could explain 2.9% of the variability in MPV (p=0.01). In conclusion, patients undergoing coronary stenting who carry the G-variant of the rs342293 SNP which is associated with larger MPV are at higher risk for adverse cardiovascular outcome.

Polymer-Free Drug-Eluting Stents: An Overview of Coating Strategies and Comparison with Polymer-Coated Drug-Eluting Stents

Clinical evaluations have proven the efficacy of drug-elution stents (DES) in reduction of in-stent restenosis rates as compared to drug-free bare metal stents (BMS). Typically, DES are metal stents that are covered with a polymer film loaded with anti-inflammatory or antiproliferative drugs that are released in a sustained manner. However, although favorable effects of the released drugs have been observed, the polymer coating as such has been associated with several adverse clinical effects, such as late stent thrombosis. Elimination of the polymeric carrier of DES may therefore potentially lead to safer DES. Several technologies have been developed to design polymer-free DES, such as the use of microporous stents and inorganic coatings that can be drug loaded. Several drugs, including sirolimus, tacrolimus, paclitaxel, and probucol have been used in the design of carrier-free stents. Due to the function of the polymeric coating to control the release kinetics of a drug, polymer-free stents are expected to have a faster drug elution rate, which may affect the therapeutic efficacy. However, several polymer-free stents have shown similar efficacy and safety as the first-generation DES, although the superiority of polymer-free DES has not been established in clinical trials.

First in vitro and in vivo results of an anti-human CD133-antibody coated coronary stent in the porcine model

BACKGROUND

Drug-eluting stents successfully reduce restenosis at the cost of delayed re-endothelialization. A novel concept to enhance re-endothelialization is the use of antibody-coated stents which capture circulating progenitor cells. A CD34-positive-cell-capturing stent was recently developed with conflicting clinical results. CD133 is a glycoprotein expressed on circulating hematopoietic and putative endothelial-regenerating cells and may be superior to CD34.

OBJECTIVE

The aim of our study was to develop a CD133-cell-capturing bare-metal stent and investigate feasibility, safety, and efficacy of CD133-stents in terms of re-endothelialization and neointima inhibition.

METHODS AND RESULTS

Anti-human CD133-antibodies were covalently attached to bare-metal stents. In vitro, binding capacity of CD133-stents was studied, revealing a significantly higher affinity of human CD133-positive cells to CD133-stents compared with mononuclear cells (MNCs). In vivo, 15 landrace pigs received BMS and CD133-stents in either RCX or LAD (n = 30 stents). Re-endothelialization was examined on day 1 (n = 4), 3 (n = 4) and day 7 (n = 4) using scanning electron microscopy. In histology, injury and inflammatory scores, as well as diameter restenosis were evaluated after day 7 (n = 3), 14 (n = 4), and 28 (n = 2). Overall no reduction in re-endothelialization, diameter stenosis or inflammatory score was seen with CD133-stents.

CONCLUSION

Stent coating with anti-human CD133-antibodies was successfully achieved with effective binding of CD133-positive cells. However, in vivo, no difference in re-endothelialization or neointima formation was evident with the use of CD133-stents compared with BMS. The low number of circulating CD133-positive cells and an increase in unspecific binding of MNCs over time may account for the observed lack of efficacy.

Impact of metabolic syndrome on re-stenosis development: role of drug-eluting stents

Metabolic syndrome (MetS) is defined as a cluster of numerous cardiovascular risk factors, which encompasses obesity, dyslipidaemia, insulin resistance and hypertension. Patients with MetS are more prone to developing cardiovascular events than other patients. To date, several approaches such as physical exercise, dietary control and invasive and non-invasive therapeutic interventions for dyslipidaemia, hypertension and insulin resistance have been used to manage MetS. However, there is a progressive elevation in the incidence of fatal and non-fatal cardiovascular events due to the increased prevalence of obesity and diabetes. Percutaneous coronary intervention has emerged over the last few years as an effective revascularisation strategy for those with coronary artery disease, in parallel with the development of effective anti-platelet medications and newer drug-eluting stents. In recent years, considerable research efforts have been undertaken to elucidate the pathophysiology of re-stenosis and develop strategies to prevent re-stenosis following percutaneous transluminal coronary angioplasty and stent implantation. Although the rate of stent re-stenosis and target-lesion revascularisation has been reduced, there is little information in the literature on the outcome of MetS in the pathophysiology of re-stenosis. In this review article, we summarise the recent development and progress on re-stenosis and the role of drug-eluting stents, particularly in MetS.

Phenotyping vs. genotyping for prediction of clopidogrel efficacy and safety: the PEGASUS-PCI study

BACKGROUND

Prognostic values of genotyping and phenotyping for assessment of clopidogrel responsiveness have been shown in independent studies.

OBJECTIVES

To compare different assays for prediction of events during long-term follow-up.

METHODS

In this prospective cohort study polymorphisms of CYP2C19*2 and CYP2C19*17 alleles, vasodilator-stimulated phosphoprotein phosphorylation (VASP) assay, multiple electrode aggregometry (MEA), cone and platelet analyser (CPA) and platelet function analyser (PFA-100) were performed in 416 patients undergoing percutaneous coronary intervention. The rates of events were recorded during a 12-month follow-up.

RESULTS

Platelet aggregation by MEA predicted stent thrombosis (2.4%) better (c-index = 0.90; P < 0.001; sensitivity = 90%; specificity = 83%) than the VASP assay, CPA or PFA-100 (c-index < 0.70; P > 0.05; sensitivity < 70%; specificity < 70% for all) or even the CYP2C19*2 polymorphism (c-index < 0.56; P > 0.05; sensitivity = 30%; specificity = 71%). Survival analysis indicated that patients classified as poor responders by MEA had a substantially higher risk of developing stent thrombosis or MACE than clopidogrel responders (12.5% vs. 0.3%, P < 0.001, and 18.5% vs. 11.3%, P = 0.022, respectively), whereas poor metabolizers (CYP2C19*1/*2 or *2/*2 carriers) were not at increased risks (stent thrombosis, 2.7% vs. 2.5%, P > 0.05; MACE, 13.5% vs. 12.1%, P = 0.556). The incidence of major bleedings (2.6%) was numerically higher in patients with an enhanced vs. poor response to clopidogrel assessed by MEA (4% vs. 0%) or in ultra-metabolizers vs. regular metabolizers (CYP2C19*17/*17 vs. CYP2C19*1/*1; 9.5% vs. 2%). The classification tree analysis demonstrated that acute coronary syndrome at hospitalization and diabetes mellitus were the best discriminators for clopidogrel responder status.

CONCLUSIONS

 Phenotyping of platelet response to clopidogrel was a better predictor of stent thrombosis than genotyping.

Cost-effectiveness of paclitaxel-coated balloon angioplasty and paclitaxel-eluting stent implantation for treatment of coronary in-stent restenosis in patients with stable coronary artery disease

BACKGROUND

Recent studies have demonstrated the safety and efficacy of drug-coated balloon (DCB) angioplasty for the treatment of coronary in-stent restenosis (ISR). The cost-effectiveness of this practice is unknown.

METHODS

A Markov state-transition decision analytic model accounting for varying procedural efficacy rates, complication rates, and cost estimates was developed to compare DCB angioplasty with drug-eluting stent (DES) placement in patients with bare-metal stent (BMS)-ISR. Data on procedural outcomes associated with both treatment strategies were derived from the literature, and the cost analysis was conducted from a health care payer perspective. Effectiveness was expressed as life-years gained.

RESULTS

In the base-case analysis, initial procedure costs amounted to €3,604.14 for DCB angioplasty and to €3,309.66 for DES implantation. Over a 12-month time horizon, the DCB strategy was found to be less costly (€4,130.38 vs. €5,305.30) and slightly more effective in terms of life expectancy (0.983 vs. 0.976 years) than the DES strategy. Extensive sensitivity analyses indicated that, in comparison with DES implantation, the cost advantage of the DCB strategy was robust to clinically plausible variations in the values of key model input parameters. The variables with the greatest impact on base-case results were the duration of dual antiplatelet therapy with acetylsalicylic acid and clopidogrel after DCB angioplasty, the use of generic clopidogrel, and variations in the costs associated with the DCB device.

CONCLUSION

DCB angioplasty is a cost-effective treatment option for coronary BMS-ISR. The higher initial costs of DCB are more than offset by later cost-savings, predominantly as a result of reduced medication costs.

Localized ultrasound enhances delivery of rapamycin from microbubbles to prevent smooth muscle proliferation

Microbubble contrast agents have been shown to enhance reagent delivery when activated by ultrasound. We hypothesized that ultrasound would enhance delivery of rapamycin, an antiproliferative agent, from the shell of microbubbles, thus reducing proliferation of vascular smooth muscle cells. Our objective was to determine optimal ultrasound parameters that maximized therapeutic efficacy, maintained cell adherence, and minimized the drug exposure time. In vitro assays determined that ultrasound (1 MHz, 0.5% duty cycle) is required to successfully deliver rapamycin from microbubbles and reduce proliferation. Co-injection of rapamycin with control microbubbles did not result in a reduction in proliferation. Successful reduction in proliferation (>50%) required pulses at least 10 cycles in length and at least 300 kPa peak negative pressure at which point 90% of cells remained adherent. The anti-proliferative effect was also localized within a 6mm wide zone by focusing the ultrasound beam.