Thin-strut Stent Research Articles

Longitudinal stent compression of everolimus-eluting stent: A report of 2 cases

Second generation drug eluting stents (DES) have shown better safety and efficacy in comparison to first generation DES, because of thinner struts, nondurable polymers and coating with better anti-proliferative drugs. The newer DES with cobalt alloy base have demonstrated a greater trackability, deliverability, conformability, flexibility and radio-opacity. However, these thin strut stents have a downside of poor longitudinal axial strength, and therefore get easily deformed/compressed at their end with a slight trauma during exchange of various catheters. We hereby report two cases of "longitudinal stent compression (LSC)" of everolimus-eluting stent, which happened during percutaneous coronary intervention of right coronary artery. Both the cases were successfully managed with non-compliant balloon dilatation. Various reasons for LSC and its management are discussed in the article.

Second Generation Drug-Eluting Stents: A Review of the Everolimus-Eluting Platform

Everolimus-eluting stents (EES) represent the next generation of drug-eluting stents (DES). Important design modifications include thin strut stent backbones, less inflammatory and more biocompatible polymers, and lower drug dosing. The cobalt chromium EES fluoropolymer XIENCE V stent has been the most extensively studied of such stents. In animal models, this stent demonstrated minimal vessel inflammation, a biologically active endothelium with strut coverage similar to a bare metal stent, and inhibition of intimal hyperplasia comparable to that seen with sirolimus-eluting stents. The SPIRIT family of clinical trials demonstrated low rates of late loss, and clinical restenosis, as well as low rates of very late stent thrombosis. These excellent clinical outcomes addressed limitations of the 1st generation DES, and substantiated widespread clinical use of the EES platform.

Flow Patterns at Stented Coronary Bifurcations

The ideal bifurcation stenting technique is not established, and data on the hemodynamic characteristics at stented bifurcations are limited. We used computational fluid dynamics analysis to assess hemodynamic parameters known affect the risk of restenosis and thrombosis at coronary bifurcations after the use of various single- and double-stenting techniques. We assessed the distributions and surface integrals of the time averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (t(r)). Single main branch stenting without side branch balloon angioplasty or stenting provided the most favorable hemodynamic results (integrated values of TAWSS=4.13·10(-4) N, OSI=7.52·10(-6) m(2), t(r)=5.57·10(-4) m(2)/Pa) with bifurcational area subjected to OSI values >0.25, >0.35, and >0.45 calculated as 0.36 mm(2), 0.04 mm(2), and 0 mm(2), respectively. Extended bifurcation areas subjected to these OSI values were seen after T-stenting: 0.61 mm(2), 0.18 mm(2), and 0.02 mm(2), respectively. Among the considered double-stenting techniques, crush stenting (integrated values of TAWSS=1.18·10(-4) N, OSI=7.75·10(-6) m(2), t(r)=6.16·10(-4) m(2)/Pa) gave the most favorable results compared with T-stenting (TAWSS=0.78·10(-4) N, OSI=10.40·10(-6) m(2), t(r)=6.87·10(-4) m(2)/Pa) or the culotte technique (TAWSS=1.30· 10(-4) N, OSI=9.87·10(-6) m(2), t(r)=8.78·10(-4) m(2)/Pa). In the studied models of computer simulations, stenting of the main branch with our without balloon angioplasty of the side branch offers hemodynamic advantages over double stenting. When double stenting is considered, the crush technique with the use of a thin-strut stent may result in improved immediate hemodynamics compared with culotte or T-stenting.

Accordion effect in a thin-strut coronary stent

Longitudinal compression (accordion effect) of modern thinner-strut stents has been recently recognised. We report a typical case of longitudinal stent compression caused by a post-dilatation balloon.

LONGITUDINAL STENT DEFORMATION: QUANTITATIVE CORONARY ANGIOGRAPHIC ANALYSIS FROM THE PERSEUS WH AND PLATINUM WH RANDOMIZED CONTROLLED CLINICAL TRIALS

Stent platform characteristics, including material and design, influence both periprocedural and late performance. Recent reports have suggested susceptibility of novel thin-strut coronary stents to incur longitudinal stent deformation during or following deployment. This analysis focuses on the ION

Treatment of Intracranial Atherosclerotic Disease with a Balloon-Expandable Paclitaxel Eluting Stent

PurposeProcedural safety and high rates of in-stent recurrent stenotic lesions (ISR) remain a concern in the endovascular treatment of intracranial atherosclerotic disease (ICAD). In the present study technical feasibility, safety and efficacy of the paclitaxel eluting balloon-expandable coronary stent Coroflex® Please was assessed in the treatment of ICAD.MethodsA total of 95 patients (79 male; median age 68 years) with 106 intracranial atherosclerotic stenotic lesions underwent endovascular treatment using Coroflex® Please stents (B. Braun, Melsungen, Germany). Location and degree of target stenoses before and after treatment and at follow-up and adverse clinical sequelae of treatment were registered. Post-procedural medication included 100 mg acetylsalicylic acid (ASA) and 75 mg clopidogrel for 1 year. Angiographic follow-up was scheduled for 6, 12, 26 and 52 weeks after the treatment.ResultsThe lesion locations were as follows: internal carotid artery (ICA) petrous (n = 44, 42%), ICA cavernous (n = 43, 41%), ICA paraclinoid (n = 4, 4%), intradural vertebral artery (VA; n = 11, 10%) and basilar artery (BA; n = 4, 4%). Of the lesions seven could not be treated due to difficult anatomy and stent stiffness (7% technical failure rate). The combined post-interventional neurological morbidity and mortality rate, including stroke, intracerebral hemorrhage (ICH), subarachnoid hemorrhage (SAH) and carotid cavernous fistula (CCF) was n = 4 (3.7%) within and n = 1 (0.9%) at and beyond 30 days, respectively. Angiographic and clinical follow-up examinations were carried out for 78 (78%) of the lesions (mean 16.1 months, maximum 48 months). Asymptomatic recurrent stenosis was seen in 3 out of 78 (3.8%) lesions and there was 1 case of late stent thrombosis (0.9%).ConclusionsTreatment of ICAD using drug-eluting coronary stents is safe and effective but technical failure due to stent stiffness remains a problem. Application of the more flexible, newest generation thin-strut stents, however, shows promising results.

Predictors of early and late outcomes after everolimus and paclitaxel-eluting coronary stents

To evaluate whether the improved outcomes with newer generation drug-eluting stents (DES) utilising thin-strut stents are consistent among different patient and angiographic subgroups. Clinical outcomes over three years were collected in the SPIRIT III trial comparing the XIENCE V® everolimus-eluting stents (EES) (Abbott Vascular, Santa Clara, CA, USA) to the TAXUS® paclitaxel-eluting stents (PES) (Boston Scientific, Natick, MA, USA). Potential predictors of adverse clinical outcomes were assessed using demographic, clinical, and procedural variables by logistic and Cox regression analyses. For three-year target vessel failure, the independent predictors identified by Cox regression were number of vessels treated (HR=2.19 [1.50, 3.19], p<0.0001), HbA1c (%) (HR=1.17 [1.05, 1.29], p=0.004), total cholesterol (>200 mg/dl) (HR=1.63 [1.13, 2.36], p=0.009), and female gender (HR=1.42 [1.01, 2.01], p=0.05). Logistic regression analysis identified the same predictors except for the female gender. The clinical results with EES compared to PES were consistent among the multiple subgroups examined with the possible exception of patients with diabetes. Clinical factors and stent type were the most important multivariable predictors of adverse clinical outcomes in this contemporary trial of first versus second generation DES. The benefit of the EES compared to the PES was consistent across a wide range of patient and angiographic subgroups with the possible exception of patients with diabetes.

Stents convencionais de aço inoxidável vs. cromo-cobalto: impacto clínico da liga metálica no cenário atual - registro InCor

INTRODUÇÃO: Há alguns anos estudos demonstraram que stents de cromo-cobalto, com hastes mais finas, reduziram de forma expressiva a reestenose coronária, comparativamente aos stents convencionais de aço inoxidável disponíveis na época. Desde então, stents com hastes < 100 µm e diferentes ligas metálicas estão disponíveis para uso clínico. O objetivo deste estudo foi avaliar a existência de diferenças nos resultados clínicos de pacientes submetidos a intervenção coronária percutânea (ICP) com stents de hastes finas e diferentes ligas metálicas. MÉTODOS: Registro unicêntrico, em que foram comparados os resultados de pacientes submetidos a ICP com stent de aço inoxidável (n = 135) vs. stent de cromo-cobalto (n = 181). O desfecho primário foi a ocorrência de eventos cardíacos adversos maiores (ECAM), definidos pela ocorrência de óbito, infarto agudo do miocárdio (IAM) ou revascularização do vaso-alvo (RVA) no seguimento tardio. RESULTADOS: A média de idade dos pacientes foi de 64 ± 11 anos, com 32,6% de diabéticos e 65,5% com síndrome coronária aguda à admissão, sem diferenças na maioria das características clínicas e angiográficas avaliadas entre os grupos. Na comparação das características do procedimento, a estratégia de implante direto do stent foi mais frequente no grupo cromo-cobalto (30,3% vs. 40,2%; P = 0,04). Ao final de mediana de 500 dias de seguimento, não houve diferenças significativas entre os grupos para a ocorrência de ECAM (15,5% vs. 16,5%; P = 0,6), óbito (4,6% vs. 6,8%; P = 0,29), IAM (2,7% vs. 4,1%; P = 0,41) ou RVA (10,4% vs. 10,1%; P = 0,97). CONCLUSÕES: Nessa população do mundo real os stents de cromo-cobalto apresentaram eficácia e segurança semelhantes às dos stents de aço inoxidável, porém com menor necessidade de instrumentação coronária.

129 Detection of coronary in-stent restenosis by 64-slice Computed Tomography in asymptomatic patients after acute myocardial infarction treated by primary angioplasty using stents with thin struts

The occurrence of instent restenosis (ISR) after myocardial infarction (MI) treated by primary angioplasty is considered as a factor of poor prognosis. The methods to detect ISR are still debated in asymptomatic patients in whom functional scintigraphic or ultrasound investigations are usually proposed. Our study sought to evaluate the effectiveness of anatomic diagnosis of ISR by 64-slice Multidetector Computed Tomography (MDCT) in patients (pts) treated with one or more stents whose thickness of strut is less than 100 μm. The diagnosis of ISR by MDCT was controlled by coronary angiography, pts without ISR at MDCT were followed clinically by physicians according to their practice. We included from January 2007 to June 2009 54 pts (50 men and 4 women) of 53.0 ± 10.8 years old. The culprit coronary lesion of MI was treated with 1.4 ± 0.6 stents (3.1 ± 0.4 mm diameter and 19.9 ± 9.7 mm length). Seventy four stents with strut of 84.6 ± 8.1 μm thickness were implanted on culprit lesions. The treated artery was LAD in 19 pts (35.2%), circumflex in 8 pts (14.8%) and RCA in 27 pts (50%). MDCT was performed 206 ± 136 days after MI. Seventeen pts (31.4%) received beta-blocker before acquisition, heart rate was 58.7 ± 7.2 bpm and effective radiation dose was 16.3 ± 1.5 msv. Two stents (2.7%) were considered nonassessable in 2 pts (3.7%). MDCT showed ISR in 14 pts (26.9%). Coronary angiography performed in 12 pts confirmed ISR in 9 pts 55 ± 50 days after MDCT. The positive predictive value of angiographic ISR after MDTC was 75%. Thirty eight pts without ISR were followed during 392 ± 200 days. No patient died, 2 pts experienced MI in relation to a definite late stent thrombosis, no patient had revascularization for ISR. Thus 64-slice MDCT could be a useful tool in systematic detection of ISR after MI in asymptomatic patient treated with thin strut stents. An evaluation of MDCT in addition to conventional functional methods should be discussed on a larger population.

Challenges and innovations in coronary bifurcation stenting: the Tryton™ side-branch stent

Percutaneous coronary intervention (PCI) for bifurcation lesions is challenging despite the use of many different techniques and strategies, and is a predictor of procedural, early and late adverse outcomes, even in this drug-eluting stent era. The current limitations of PCI for bifurcation lesions are due, in part, to the use of stents designed and refined for the treatment of lesions in straight coronary segments. This has led several groups to develop novel dedicated stents specifically designed to treat bifurcation lesions. Among them, the Tryton™ side-branch stent has several innovative features that provide complete stent coverage and uniform strut apposition at the bifurcation site with full expansion of the side-branch ostium. This device is a balloon-expandable cobalt–chromium thin-strut bare-metal stent that is designed to integrate with ‘workhorse’ drug-eluting stents. Early clinical data are very encouraging, showing very low rates of neointimal proliferation (late loss at the branch site = 0....

Clinical and Angiographic Outcomes After Treatment of De Novo Coronary Stenoses With a Novel Platinum Chromium Thin-Strut Stent: Primary Results of the PERSEUS (Prospective Evaluation in a Randomized Trial of the Safety and Efficacy of the Use of the TAXUS Element Paclitaxel-Eluting Coronary Stent System) Trial

The aim of this study was to evaluate the safety and efficacy of the novel platinum chromium TAXUS Element paclitaxel-eluting stent (PES) compared with the TAXUS Express PES (Boston Scientific, Natick, Massachusetts) in treating coronary artery stenoses. The TAXUS Element is a novel thin-strut (81 microm), platinum chromium alloy PES designed to improve radial strength, radiopacity, and deliverability, while safely providing comparable restenosis benefit compared with a previous-generation PES. The PERSEUS (Prospective Evaluation in a Randomized Trial of the Safety and Efficacy of the Use of the TAXUS Element Paclitaxel-Eluting Coronary Stent System) Workhorse (WH) trial is a prospective, randomized (3:1), controlled, multicenter study of the TAXUS Element (vs. TAXUS Express) PES for the treatment of de novo coronary atherosclerotic lesions<or=28 mm in length in reference vessels>or=2.75 to <or=4.0 mm in diameter. The primary end point was the 12-month rate of target lesion failure, and the secondary end point was 9-month angiographic in-segment percentage diameter stenosis. The study was powered to demonstrate noninferiority to TAXUS Express for both end points. The intent-to-treat analysis included 1,262 patients (320 TAXUS Express, 942 TAXUS Element). The TAXUS Element was noninferior to TAXUS Express with respect to both the incidence of target lesion failure (5.57% vs. 6.14%, respectively; difference: 0.57%; 95% credible interval: 1.85%; Bayesian posterior probability of noninferiority=0.9996) and percentage diameter stenosis (ln[%DS] 3.09 vs. 3.12, respectively; difference: 0.03; 95% credible interval: 0.11; Bayesian posterior probability of noninferiority=0.9970). No differences in clinical outcomes to 12 months were observed between stent treatments, and stent thrombosis was infrequent (0.3% Express, 0.4% Element). At 1 year, the TAXUS Element is comparable in efficacy to the TAXUS Express PES. Furthermore, no safety concerns related to the novel platinum chromium alloy or stent design were observed. (A Prospective Evaluation in a Randomized Trial of the Safety and Efficacy of the Use of the TAXUS Element Paclitaxel-Eluting Coronary Stent System for the Treatment of De Novo Coronary Artery Lesions; NCT00484315).

A Randomized Comparison of the Endeavor Zotarolimus-Eluting Stent Versus the TAXUS Paclitaxel-Eluting Stent in De Novo Native Coronary Lesions: 12-Month Outcomes From the ENDEAVOR IV Trial

The ENDEAVOR IV (Randomized Comparison of Zotarolimus-Eluting and Paclitaxel-Eluting Stents in Patients with Coronary Artery Disease) trial evaluated the safety and efficacy of the zotarolimus-eluting stent (ZES) compared with the paclitaxel-eluting stent (PES). First-generation drug-eluting stents have reduced angiographic and clinical restenosis, but long-term safety remains controversial. A second-generation drug-eluting stent, which delivers zotarolimus, a potent antiproliferative agent, via a biocompatible phosphorylcholine polymer on a cobalt alloy thin-strut stent has shown promising experimental and early clinical results. This is a prospective, randomized (1:1), single-blind, controlled trial comparing outcomes of patients with single de novo coronary lesions treated with ZES or PES. The primary end point was noninferiority of 9-month target vessel failure defined as cardiac death, myocardial infarction, or target vessel revascularization. Among a total of 1,548 patients assigned to ZES (n = 773) or PES (n = 775), at 9 months, ZES was noninferior to PES with rates of target vessel failure 6.6% versus 7.1%, respectively (p(noninferiority) < or = 0.001). There were fewer periprocedural myocardial infarctions with ZES (0.5% vs. 2.2%; p = 0.007), whereas at 12 months, there were no significant differences between groups in rates of cardiac death, myocardial infarction, target vessel revascularization, or stent thrombosis. Although incidence of 8-month binary angiographic in-segment restenosis was higher in patients treated with ZES versus PES (15.3% vs. 10.4%; p = 0.284), rates of 12-month target lesion revascularization were similar (4.5% vs. 3.2%; p = 0.228), especially in patients without planned angiographic follow-up (3.6% vs. 3.2%; p = 0.756). These findings demonstrate that ZES has similar clinical safety and efficacy compared with PES in simple and medium complexity single de novo coronary lesions. (ENDEAVOR IV Clinical Trial; NCT00217269).

A third generation ultra-thin strut cobalt chromium stent: histopathological evaluation in porcine coronary arteries

The present study was designed to evaluate a novel third generation bare-metal stent (BMS) comprised of an ultra-thin-strut, cobalt-chromium platform with fixed geometry, uniform cell size, and superior surface finish in a porcine coronary artery model. A total of 47 BMS of two types were implanted in pig coronary arteries using QCA to optimise stent apposition: a commercially available cobalt alloy thin-strut stent (91 microm) as control (Driver; n=17), and an ultra-thin-strut (65 microm) cobalt-chromium stent (Protea; n=18). Animals underwent angiographic restudy and termination one week and one month post-implant for coronary artery histology. In addition, 12 overlapping Protea stents were analysed at one month. At one week, comparable thin neointima and mild inflammation were observed in both groups. At one month, Protea demonstrated significantly lower angiographic % stenosis (2+/-1% vs. 17+/-5%, p=0.006), intimal thickness (0.11+/-0.01 mm vs. 0.23+/-0.03 mm, p=0.003), and histologic % area stenosis (19+/-2% vs. 32+/-3%, p=0.003). Mean stent strut injury scores were low and similar between groups. Angiographic % stenosis, intimal thickness, and histologic % area stenosis of overlapping Protea stents were 3+/-1%, 0.13+/-0.01 mm, and 22+/-2%, respectively, and similar to the single Protea group. Stable fibrocellular neointimal incorporation, with complete endothelialisation and minimal inflammation, were observed at one month in all stents, including overlapped Protea segments. When compared to a commercially available cobalt alloy BMS, the new third generation Protea stent demonstrated favourable coronary arterial response with significant reduction of neointimal formation in the porcine model. Our results showed how seemingly trivial improvements to the BMS technology can result in substantial biological responses. Future, long-term investigations are needed to ascertain the clinical applicability and implications of these findings.

Resultados clínicos iniciais do primeiro stent de cromo-cobalto concebido no Brasil

Initial Clinical Results of the First Cobalt-Chromium Stent Designed in Brazil Background: Thin-strut cobalt-chromium stents have greater flexibility and probably have less neointimal proliferation than stainless steel stents. Methods: The Cronus (Scitech Produtos Medicos, Goiânia, Brazil) registry is an international, non-randomized, prospective study designed to evaluate the efficacy and safety of a novel thin-strut cobalt-chromium stent in patients with coronary artery disease. A total of 69 lesions were treated in 53 patients included in this analysis. Results: The device success was 98.5%. Mean late luminal loss was 0.7 ± 0.5 mm, binary restenosis occurred in 15% and target vessel revascularization in 11.3% of the cases. The incidence of major adverse cardiac events (death, myocardial infarction or target vessel revascularization) was 24.4% after 317 ± 80 days of follow-up. Conclusion: Our initial results demonstrate that the novel Cronus stent proved to be safe and effective, with clinical results similar to other available thin-strut stents. DESCRIPTORS: Stents. Angioplasty, transluminal, percutaneous coronary. Prostheses and implants.

Determination of the influence of stent strut thickness using the finite element method: implications for vascular injury and in-stent restenosis

Many clinical studies, including the ISAR-STEREO trial, have identified stent strut thickness as an independent predictor of in-stent restenosis where thinner struts result in lower restenosis than thicker struts. The aim of this study was to more conclusively identify the mechanical stimulus for in-stent restenosis using results from such clinical trials as the ISAR-STEREO trial. The mechanical environment in arteries stented with thin and thicker strut stents was investigated using numerical modelling techniques. Finite element models of the stents used in the ISAR-STEREO clinical trial were developed and the stents were deployed in idealized stenosed vessel geometries in order to compare the mechanical environment of the vessel for each stent. The stresses induced within the stented vessels by these stents were compared to determine the level of vascular injury caused to the artery by the stents with different strut thickness. The study found that when both stents were expanded to achieve the same initial maximum stent diameter that the thinner strut stent recoiled to a greater extent resulting in lower luminal gain but also lower stresses in the vessel wall, which is hypothesised to be responsible for the lower restenosis outcome. This study supports the hypothesis that arteries develop restenosis in response to injury, where high vessel stresses are a good measure of that injury. This study points to a critical stress level in arteries, above which an aggressive healing response leads to in-stent restenosis in stented vessels. Stents can be designed to reduce stresses in this range in arteries using preclinical tools such as numerical modelling.

Percutaneous Coronary Intervention in Tortuous Coronary Arteries: Associated Complications and Strategies to Improve Success

Percutaneous intervention of tortuous coronary arteries can be challenging. We describe four cases that illustrate complications associated with coronary tortuosity (coronary dissection and stent loss) and strategies that can improve procedural success (such as use of soft delivery catheters, deep guide intubation, meticulous vessel preparation, and use of short, thin-strut stents).

Abstract 2553: Novel Cobalt-Chromium Ultra-Thin Strut Stent: Feasibility, Vascular Compatibility, and Safety Evaluation in Porcine Coronary Arteries

Stent-strut thickness is related to in-stent restenosis. Therefore, modern bare-metal stents (BMS) with lower strut thickness are in development. We sought to evaluate a new ‘third-generation’ BMS comprising an ultra-thin-strut, cobalt-chromium platform with fixed geometry and uniform cell sizes, in a clinically relevant animal model. 36 BMS of two types were implanted in pig coronaries using quantitative coronary angiography (QCA) to optimize stent apposition: a commercially available cobalt alloy thin-strut stent (91μm) as control (n=18), and an ultra-thin-strut (65μm) cobalt-chromium stent (Protea CoCr; n=18). Animals underwent angiographic restudy and termination 1-wk and 1-mo post-implant for coronary artery histology. In addition, 12 overlapping Protea CoCr stents were analyzed at 1-mo. All stents deployed without difficulties. Thin neointima and mild inflammation was seen in both groups at 1-wk. For 1-mo, QCA % diameter stenosis was significantly less for Protea CoCr (2±5% vs. 17±16%, p=0.032). By histomorphometry, intima thickness (0.11±0.05mm vs. 0.23±0.11mm, p=0.003) and % area stenosis (19±1% vs. 32±11%, respectively, p=0.004) were also significantly lower for Protea CoCr. The strut injury score was low and similar between the two groups. QCA % stenosis; intima thickness; and % area stenosis of overlapping Protea CoCr were 3±3%, 0.13±0.02mm, and 22±4%, respectively. Stable fibrocellular neointimal incorporation of all stents including overlapped Protea CoCr, with complete endothelialization and minimal inflammation, was seen at one month. Protea CoCr showed favorable arterial response with significant reduction of neointima formation compared to a commercial cobalt alloy BMS, one month post implant in pig coronary arteries. This ultra-thin-strut stent platform therefore appears to be a suitable and attractive alternative to current BMS. Combining the lower levels of neointima formation, fixed geometry, and uniform cell size, the Protea CoCr may be a preferred platform for next-generation drug-eluting stents.

A novel thin-strut cobalt-chromium stent for inhibition of neointimal formation in a porcine coronary artery model

A novel thin-strut cobalt-chromium stent for inhibition of neointimal formation in a porcine coronary artery model

Dose Perturbation Caused by Stents: Experiments with a Model 90Sr/90Y Source

Biological effects of intravascular brachytherapy are very sensitive to discrepancies between the prescription and the applied dose. If brachytherapy is aimed at in-stent restenosis, shielding and shadowing effects of metallic stents may change the dose distribution relative to that produced by the bare source. The development of new generations of stents inspired us to a new experimental study in this field. The effect was studied for 14 stents which we have recently encountered in clinical practice. The model source was a continuous 20-mm column of (90)Sr/(90)Y solution sealed in a 1-mm-I.D. Plexiglas capillary. The dose distribution in the Plexiglas phantom was mapped using GafChromic MD-55-2 film. The stent masses varied from 2.5 to 25 mg; the strut thicknesses, from 0.075 to 0.15 mm; and the atomic numbers of stent materials, from 24 (Cr) to 79 (Au). Dose perturbations depend on a variety of stent features. Local reduction of the mean dose rates near the reference distance (r(0) = 2 mm) varied from 11% to 47%. No simple correlation was found between these data and stent characteristics, but it seems that the atomic number of the stent material is less important than the strut thickness and mesh density. The results provide a warning that clinical indications for in-stent radiation therapy must always be confronted with another aspect of the patient's history: the kind of implanted stent. Intravascular brachytherapy using pure beta sources may be recommended only for patients "wearing" light, thin-strut stents. The presence of thick-strut stents is a contraindication for this modality, due to excessive dose perturbation.

Drug-Eluting Stents Compared With Thin-Strut Bare Stents for the Reduction of Restenosis: A Prospective, Randomized Trial

Aim Drug-eluting stents have considerably reduced restenosis. Their relative merits have been assessed on the basis of comparisons made with control bare stents with thick struts. However, increased strut thickness negatively affects restenosis. No direct comparisons between drug-eluting stents and bare stents with thin struts have been performed. The aim of this study was to evaluate the relative efficacy of sirolimus-eluting stents (Cypher™) as compared with that of bare stents with thin struts (BeStent™ 2). Methods and results A total of 500 patients with coronary artery disease were randomly assigned to receive a Cypher stent or BeStent. The primary endpoint was angiographic restenosis defined as a stenosis diameter ≥50% at 6-month angiographic follow-up. The secondary endpoint was the need for target vessel revascularization (TVR) during the year following the procedure. Follow-up angiography was performed in 81.8% of the patients. Patients treated with Cypher stents had a lower angiographic restenosis rate [8.3 vs. 25.5%, relative risk, 0.33 (95% confidence interval, 0.19–0.56), P <0.001] and a lower incidence of TVR [7.2 vs. 18.8%, relative risk, 0.38 (0.22–0.66), P <0.001]. For smaller vessels (<2.8 mm), the angiographic restenosis rates were 7.0% with the Cypher stent and 34.2% with the BeStent ( P <0.001). For larger vessels (≥2.8 mm), angiographic restenosis rates were 10.0% with the Cypher stent and 13.1% with the BeStent ( P =0.52). Conclusion The drug-eluting stent, Cypher, is associated with a significantly lower risk of restenosis compared with the bare thin-strut BeStent. The advantage of the Cypher stent is vastly reduced in large vessels.