NIR Stent Research Articles

Application of finite element method to comparing the NIR stent with the multi-link stent for narrowings in coronary arteries

‘Stent versus stent’ studies are a kind of randomized trials which are designed to show the superiority of the new stent designs compared with the previously approved ones. These studies are usually used by regulatory agencies, such as the U.S. Food and Drug Administration (FDA), to give an approval to new stent designs. The problem with these clinical trials is their high cost and difficulty. In this paper, a numerical alternative for ‘stent versus stent’ complicated clinical studies is presented. A finite element model is developed to investigate the influence of stent design on the outcome after coronary stent placement. Two commercially available stents (the NIR and Multi-Link stents) are modeled and their behavior during the deployment is compared in terms of stress distribution, radial gain, outer diameter changes and foreshortening. Moreover, the effect of stent design on the restenosis rate is investigated by comparing the stress distribution within the arteries. An analysis of the arterial wall stresses in the stented arteries indicates that the Multi-Link stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. The findings correlate with the observed clinical restenosis rates, which have reported higher restenosis rates in the NIR compared with the Multi-Link stent design.

Analysis of the stent expansion in a stenosed artery using finite element method: application to stent versus stent study.

In this article, finite element method is used to investigate the mechanical behavior of a stent and to determine the biomechanical interaction between the stent and the artery in a stenting procedure. The main objective of this study is to reach to a model close to a real condition of coronary stent placement. Unlike most of the models proposed in the literature, all the steps of the deployment of a stent in the stenotic vessel (i.e. pressure increasing, constant load pressure and pressure decreasing) are simulated in this article to show the behavior of the stent in different stages of implantation. The results indicate that the first step of deployment, that is, pressure increasing, plays a main role in the success of stent implantation. So that, in order to compare the behavior of different types of stents, it is sufficient to compare their behavior at the end of pressure increasing step. In order to show the application of the findings in stent versus stent studies, three commercially available stents (the Palmaz-Schatz, Multi-Link and NIR stents) are modeled and their behavior is compared at the end of pressure increasing step. The effect of stent design on the restenosis rate is investigated. According to the findings, the possibility of restenosis is lower for Multi-Link and NIR stents in comparison with Palmaz-Schatz stent which is in good agreement with clinical results. Therefore, the testing methodology outlined here is proposed as a simple and economical alternative for "stent versus stent" complicated clinical trials.

Clinical Experience with the NIR Stent: Retrospective Observation on Acute Results and Follow-up in 709 Patients.

The NIR stent is an expandable cellular coronary prosthesis with high flexibility and excellent trackability. The very low crossing profile, associated to the high flexibility, makes this stent suitable for complex and distal lesions. The aim of this study was to evaluate the feasibility, safety, and long-term (clinical follow-up) efficacy of elective and/or urgent deployment of the NIR stent in a broad patient group with coronary artery disease. Between June 1996 and May 1997, 986 NIR stents were implanted in 781 vessels (de novo or restenotic lesions in native vessels, saphenous vein grafts and internal mammary conduits) of 709 consecutive patients (498 men, 211 women) undergoing coronary angioplasty in two Villa Maria Group Catheterization Laboratories. Procedural angiographic success was achieved in 98.4% of all the lesions treated, ranging from 100% success rate in type A lesion to 97.6% in type C lesions (overall procedural success, 98.4%). Major adverse cardiac events (MACE) were considered from PTCA/stenting time to the patient discharge. The in-hospital MACE were limited and occurred in 15 patients: urgent surgical revascularization 0.8%, death 0.7%, sub-acute stent thrombosis 0.5% (overall in-hospital MACE rate 2.1%). Clinical follow-up data were obtained at 8.6 +/- 2.8 months following the stenting procedure. The event-free survival rate was 87.9%. The late MACE rate evaluation showed death, target lesion revascularization 9.9% (over-all late MACE rate 12.1%). The NIR stent performances in this broad patient population were excellent, showing very high procedural success rate both in normal and complex coronary anatomy. On the basis of the previous data, we can define NIR stent a safe multifunctional device suitable both for easy and complex situations. The clinical late results are very promising in term of event-free survivals and late MACE.

Comparison of Near-Wall Hemodynamic Parameters in Stented Artery Models

Four commercially available stent designs (two balloon expandable-Bx Velocity and NIR, and two self-expanding-Wallstent and Aurora) were modeled to compare the near-wall flow characteristics of stented arteries using computational fluid dynamics simulations under pulsatile flow conditions. A flat rectangular stented vessel model was constructed and simulations were carried out using rigid walls and sinusoidal velocity input (nominal wall shear stress of 10+/-5 dyn/cm2). Mesh independence was determined from convergence (<10%) of the axial wall shear stress (WSS) along the length of the stented model. The flow disturbance was characterized and quantified by the distributions of axial and transverse WSS, WSS gradients, and flow separation parameters. Normalized time-averaged effective WSS during the flow cycle was the smallest for the Wallstent (2.9 dyn/cm2) compared with the others (5.8 dyn/cm2 for the Bx Velocity stent, 5.0 dyn/cm2 for the Aurora stent, and 5.3 dyn/cm2 for the NIR stent). Regions of low mean WSS (<5 dyn/cm2) and elevated WSS gradients (>20 dyn/cm3) were also the largest for the Wallstent compared with the others. WSS gradients were the largest near the struts and remained distinctly nonzero for most of the region between the struts for all stent designs. Fully recirculating regions (as determined by separation parameter) were the largest for the Bx Velocity stent compared with the others. The most hemodynamically favorable stents from our computational analysis were the Bx Velocity and NIR stents, which were slotted-tube balloon-expandable designs. Since clinical data indicate lower restenosis rates for the Bx Velocity and NIR stents compared with the Wallstent, our data suggest that near-wall hemodynamics may predict some aspects of in vivo performance. Further consideration of biomechanics, including solid mechanics, in stent design is warranted.

Highly proliferative endothelial colony forming cells isolated from pigs with acute myocardial infarction showing high affinity on bare metal stent

Background: Coronary stent implantation can cause significant injury of vessel endothelium with an inflammatory reaction which contributes to neointimal proliferation and thrombosis resulting in-stent restenosis. Endothelial progenitor cells (EPCs) can be differentiated into endothelial cells that protect the vascular wall from damage. Acute myocardial infarction (AMI) induced in a porcine model leads to an increase in circulating high proliferative potential-endothelial colony forming cells (HPP-ECFC). This study was designed to test whether isolated porcine HPP-ECFC could be grown on bare metal coronary stent. Methods and Results: AMI was created by a PTCA balloon catheter with the proximal left anterior descending (LAD) artery being occluded just distal to the first septal perforator for 45min. Peripheral blood samples were drawn at baseline and immediately post deflation of the balloon. Circulating mononuclear cells (MNC) were isolated and cultured. Colonies of HPP-ECFC (>2000 cells/colony) were identified by a single cell assay and sorted by flow cytometry. After labeling with PKH26, the HPP-ECFC were seeded into culture slides at a density of 5 x 104 cells/cm2 with bare coronary stents (AVE, NIR, and ACS; 3 stents/each group). At day 5, the cells seeded on the stents were labeled with a nuclear DAPI stain. HPP-ECFC can only be detected in the post-MI samples and were increased 15-fold. In co-culture, HPP-ECFC coverage on the stent surface began on day 3 and complete coverage of stents occurred after day 5. The cells displayed a similar growth pattern in all of the stents and cell quantification is ongoing. Conclusion: This preliminary data demonstrates that the number of circulating HPP-ECFC significantly increases in the acute stress situation in a porcine AMI model. These cells had a high affinity to adhere to bare metal stent surfaces. HPP-ECFC coated stents may accelerate reendothelization after interventional procedures. Dongni Fong, Lan Huang, Mervin C. Yoder, Keith L. March, Dongming Hou www.iupui.edu/~icvbm Figure 1A & B. ‘Cobblestone’ morphology and Cytometry shows expression of CD31 and rare CD45. Conclusions Our findings demonstrate that peripheral blood HPP-ECFCs were increased in number following the myocardial ischemia insult in our porcine model. These cells showed a great affinity to adhere to the BMS surface. We postulate that HPP-ECFC coated stents may accelerate the re-endothelization process, prevent neointimal proliferation, and stent thrombosis. • The HPP-ECFCs were labeled by PKH26 (Sigma-Aldrich) according to the manufacturer’s instructions. • The expanded and sterilized AVE, ACS and NIR stents (n = 3/each) were separately placed into each well of 24-well plate after rinsing with culture medium.

Tracheal Reaction to Three Different Intraluminal Stents in an Animal Model of Tracheomalacia

Three different internal airway stents were studied in an animal model of tracheomalacia: the Palmaz stent (Johnson & Johnson, Warren, New Jersey) and the NIR stent (Medinol Ltd., Tel Aviv, Israel)--both made of stainless steel in the form of tubular mesh--and the Nitinol stent, made of nickel-titanium formed into a spiral shape. All three stents could be adequately stabilized in the malacic tracheal segment. The Nitinol stent (Medinol Ltd., Tel Aviv, Israel) proved to be less reactive to the tracheal mucosa, demonstrated higher biocompatibility with significantly less granulation tissue formation, and showed superior radial resistance. Extraction of the Nitinol stent also proved to be much smoother. This stent may be the stent of choice in the treatment of tracheo- and bronchomalacia.

Early results of direct coronary stenting in consecutive patients when multivessel, complex, long lesions, and small vessels are included

Background Direct coronary stenting is the dominant technique for coronary stent implantation, but previous randomized studies have strongly selected lesions to treat. To evaluate whether the results can be generalized to routine clinical practice, all consecutive patients with direct stenting in 15 hospitals were entered into a prospective registry. Single vessels and simple lesions, but also multivessel, complex and long lesions, and small vessels size (≤2.5 mm) were included. Immediately results as well as clinical events within 30 days after the procedure were evaluated. Methods Between April and November 2002, direct coronary stenting was performed in 452 consecutive patients (559 lesions) at 15 sites. Stents edge-protected by “sleeves” (SOX™ technology, NIR Stent, Boston Scientific) or with short transitional edge protection (STEP™ technology, Multilink Stents, Guidant) were selected to minimize vessel injury outside the stent edges during balloon inflation/deployment. Results Stents were successfully implanted in 96% of lesions. Lesions were multivessel in 27%, type B2-C in 40%, very angulated in 28%, calcified in 18%, and longer than 20 mm in 10% of patients. Vessels were smaller than ≤2.5 mm in 27% of patients. Direct coronary stenting was unsuccessful in 25 lesions (24 patients) characterized by more unstable angina ( p=0.07), more treated lesions ( p<0.01), and more distal locations ( p=0.001). Dissection occurred in 6% of patients, and one stent embolised. The 30-day follow-up period included 1 death (due to subacute occlusion), 11 (2.4%) acute myocardial infarctions (8 non-Q wave), and one stroke (following carotid surgery). Conclusions Direct coronary stenting yielded excellent results at 30 days although some expanded indications will be included.

The Mechanism of In-Stent Restenosis in Radius Stent-An Experimental Porcine Study-

We investigated the mechanism of in-stent restenosis in radius stents in comparison to balloon-expandable stent (NIR stent) in pigs, with a focus on extracellular matrix (ECM). Radius (n = 4) or NIR (n = 4) stents were implanted in the left coronary arteries of miniature pigs. Quantitative coronary ultrasound (QCU) was performed before, immediately after, and at 1 and 4 weeks after the implantation. The stented-coronary arteries were harvested at 4 weeks after the implantation followed by immunohistochemical, histological, reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR studies. In QCU, mean luminal areas at 4 weeks did not differ between both groups, whereas the mean stent area and neointimal area were significantly greater in the radius (p < 0.01). The immunohistochemical study revealed a significantly decreased number of neointimal macrophages and neovascularizations (p < 0.05, p < 0.01, respectively), and a stronger expression of tenascin-C in the radius. The histological study showed a larger ECM area and less neointimal cell density in the radius than in the NIR. The RT-PCR and real-time PCR analysis revealed an enhanced expression of tanascin-C mRNA in the radius than in the NIR. Increased production of ECM, especially tenascin-C, played a greater role in the neointimal formation in the radius stent than inflammation.

Cardiovascular stent design and vessel stresses: a finite element analysis

Intravascular stents of various designs are currently in use to restore patency in atherosclerotic coronary arteries and it has been found that different stents have different in-stent restenosis rates. It has been hypothesized that the level of vascular injury caused to a vessel by a stent determines the level of restenosis. Computational studies may be used to investigate the mechanical behaviour of stents and to determine the biomechanical interaction between the stent and the artery in a stenting procedure. In this paper, we test the hypothesis that two different stent designs will provoke different levels of stress within an atherosclerotic artery and hence cause different levels of vascular injury. The stents analysed using the finite-element method were the S7 (Medtronic AVE) and the NIR (Boston Scientific) stent designs. An analysis of the arterial wall stresses in the stented arteries indicates that the modular S7 stent design causes lower stress to an atherosclerotic vessel with a localized stenotic lesion compared to the slotted tube NIR design. These results correlate with observed clinical restenosis rates, which have found higher restenosis rates in the NIR compared with the S7 stent design. Therefore, the testing methodology outlined here is proposed as a pre-clinical testing tool, which could be used to compare and contrast existing stent designs and to develop novel stent designs.

The paclitaxel (TAXUS)-eluting stent: a review of its use in the management of de novo coronary artery lesions.

The TAXUSExpress stent contains paclitaxel 1 microg/mm(2). On deployment, paclitaxel is slowly released into the intimal tissue of the coronary artery to prevent cell proliferation and neointimal hyperplasia. When deployed in patients with previously untreated coronary artery lesions, the paclitaxel-eluting stent (PES) effectively reduces the need for revascularization without increasing the risk of in-stent thrombosis. While long-term outcomes data and comparative efficacy and cost-benefit trials versus other drug-eluting stents are required, the PES appears to be an attractive alternative for the management of de novo coronary artery lesions. PHARMACOLOGIC PROPERTIES: The PES comprises a stainless steel stent coated with a non-erodible biocompatible polyolefin matrix containing paclitaxel 1 microg/mm(2). Paclitaxel dose dependently inhibits vascular smooth muscle cell proliferation at therapeutic concentrations as a result of binding to and stabilizing cellular microtubules. This prevents the cascade of events associated with obstructive in-stent neointimal hyperplasia. Paclitaxel was released in a controlled manner from the stent coating in in vitro studies. The higher release rate in the first 2 days after implantation (to reduce response to implantation injury) slows over the next 8-10 days. The drug is rapidly taken up by intimal cells with minimal dispersion in the plasma; it was not detected systemically after stent deployment in clinical trials. Paclitaxel is extensively bound to proteins (88-98%), and is principally metabolized in the liver, undergoing biliary clearance after systemic administration. THERAPEUTIC EFFICACY: The efficacy of the PES was compared with that of a bare-metal stent (BMS) in a number of randomized, double-blind, multicenter trials in patients with de novo coronary artery lesions. The TAXUS I and II trials used the NIR stent, while the pivotal TAXUS IV trial used the Express stent. The primary endpoints of the well designed TAXUS II and IV trials indicated superiority for the PES over the BMS. Twice as many patients receiving the BMS required target vessel revascularization at 9 months postprocedure and, 6 months following the procedure, the in-stent neointimal volume in the PES system was only one-third of that in the BMS. The incidence of cumulative major adverse cardiac events (MACE; cardiac death, myocardial infarction [MI], or target vessel revascularization [TVR]) was also significantly lower in PES than BMS recipients at 9 and 12 months postprocedure. The incidence of cardiac death and MI was low and similar between treatment groups; however, TVR was significantly reduced by the PES versus the BMS. Other secondary endpoints, such as target lesion revascularization, luminal diameter stenosis, minimal luminal diameter, and serial intravascular ultrasound measurements from one or both trials supported these results. Preliminary analysis of the subgroup of patients with diabetes mellitus in the TAXUS IV trial suggested that the PES was also effective in diabetic patients who receive oral medications. The group receiving insulin was too small to draw meaningful conclusions. Because of the small paclitaxel dosages and the mainly local uptake, systemic adverse events associated with the PES are considered unlikely. The incidences of cardiac death and MI were very low and similar in both groups. Local events such as in-stent aneurysms, incomplete stent apposition, or in-stent thrombosis occurred at a similar rate in PES and BMS recipients. There has been no evidence of late thrombosis in PES recipients followed for 2 years. The rate of late luminal loss in the 5mm of vessel proximal and distal to the stent edges was significantly lower in PES than BMS systems. PHARMACOECONOMIC CONSIDERATIONS: Initial deployment costs associated with the PES are likely to be offset by savings in repeat procedures, according to a cost-effectiveness analysis in the UK.

New frontiers in cardiology: drug-eluting stents: Part II.

In this second part of the article, we will complete the review of drug-eluting stent technologies (Table 1) and discuss methodological and technical aspects of drug-eluting stents. View this table: TABLE 1. Drug-Eluting Stent Platforms Under Investigation ### Biological Agents (Continued) #### (1) Stents Eluting Antiproliferative Agents A number of antineoplastic medications have been considered for the prevention of restenosis. Paclitaxel and its derivatives have been the most investigated compounds of this group. ##### (a) Paclitaxel-Eluting Stents Paclitaxel (Taxol; Bristol-Myers Squibb) is a microtubule-stabilizing agent with potent antitumor activity.1 Many different platforms that use polymer coating or surface modifications to adhere paclitaxel onto the stents have been utilized over the past 2 years. ###### Preclinical Data Unlike other antimitotic agents, paclitaxel shifts the cytoskeleton equilibrium toward assembly, leading to reduced vascular cell proliferation, migration, and signal transduction.2 Paclitaxel is highly lipophilic, resulting in a rapid cellular uptake and a long-lasting effect in the cell.3 NIR stents (Boston Scientific Corp) coated with poly(lactide-co-Σ-caprolactone) copolymer and paclitaxel (200 μg/stent) were placed in porcine coronary arteries. Paclitaxel-eluting stents showed a marked reduction in neointimal and medial cell proliferation at all time points (7, 28, 56, and 180 days).4 However, arteries treated with paclitaxel showed incomplete healing, late persistence of a large number of macrophages, and fibrin deposition. Similar findings were observed with a stent platform coated with cross-linked biodegradable polymer (chondroitin sulfate and gelatin) and 42.0, 20.2, 8.6, or 1.5 μg of paclitaxel in rabbit iliac arteries.5 These studies indicate the need for a more controlled drug release of paclitaxel due to the narrow toxic-therapeutic window and high hydrophobic character of this compound. ###### Clinical Data: De Novo Lesions The QuaDS drug-eluting stent (Quanam Medical Corp) was the first drug-eluting stent implanted in human coronary arteries. This slotted tube stent has 50% of its surface area covered by multiple nonbiodegradable polyacrylate sleeves that release 7-hexanoyltaxol (called QP2 or taxane). Approximately 800 μg of the …

Comparison of a silicon carbide-coated stent versus a noncoated stent in human beings: The Tenax versus Nir Stent Study's long-term outcome

Background Stents coated with amorphous hypothrombogenic silicon carbide (a-SiC:H) have low restenosis rates in humans. Recurrence in a-SiC:H at mid-term follow-up has been shown to be similar to a stainless steel device. The long-term outcome, however, may be different. Methods Four hundred ninety-seven patients (63.4 ± 9.8 years of age) received either the a-SiC:H-coated Tenax stent (Biotronik, Berlin, Germany) or the 316L Nir stent (Boston Scientific, Maple Grove, Minn). Lesions had to be covered with one stent only (diameter ≥2.8 mm, length <20 mm). Exclusion criteria comprised acute myocardial infarction and angiographic thrombus within the target vessel. Twenty-five of 497 (5%) patients were excluded for protocol violation. Clinical follow-up was completed in 450 of 472 (95.3%) and angiographic follow-up was completed in 365 of 472 (77.3%); 22 of 472 (4.7%) patients were lost to follow-up. Results Major adverse coronary events occurred in 28 of 233 (12%) of the Tenax recipients and in 31 of 217 (14.3%) of the Nir recipients ( P = .50). Acute myocardial infarctions were less frequent in the Tenax recipients after ≥60 weeks. Premature target lesion revascularization was performed in 16 of 233 (6.9%) patients in the Tenax group and 11 of 217 (5.1%) ( P = .54) patients in the Nir group. Coronary bypass operations were similar after Tenax or Nir stent deployment (3/233 [1.3%] vs 6/217 [2.8%], P = .43), as were deaths in 7 of 233 (3%) versus 8 of 217 (3.7%) ( P = .88), respectively. Conclusions Both stents had a low rate of major adverse coronary events at 81 ± 12 weeks of follow-up, with no definite superiority of any of the devices. (Am Heart J 2003;145:e17.)

Stent-based release of paclitaxel to prevent restenosis

Paclitaxel, a microtubule-stabilizing agent with potent antiproliferative effects, has shown great promise as a locally delivered, antirestenotic therapy in both experimental and pilot clinical trials. Its protean effects, including attenuation of smooth muscle cell migration and proliferation and inhibition of cellular and subcellular components of inflammation, interfere with major elements of restenosis. In addition, paclitaxel's biophysical attributes – particularly its lipophilicity – allow for ready delivery from a polymer matrix, selective partitioning into lipid-rich atheroma in the arterial wall, with minimal systemic delivery and toxicity. In vitro selective inhibition of smooth muscle cell versus endothelial cell proliferation suggests that paclitaxel may reduce the fibromuscular proliferation following vascular injury without disrupting endothelialization. In a New Zealand White rabbit model of arterial injury, implantation of NIR stents coated with pLA/pCL bioerodible polymer loaded with paclitaxel (200 mcg, delivered over 56 days) resulted in near-total abolition of neointimal proliferation compared to vessels treated with control stents. The impact on wound healing was sustained for at least six months, long after drug delivery and polymer degradation were complete. NIR stents coated with a non-erodible polymer loaded with either a high dose of rapidly-delivered paclitaxel (“high dose” group) or a low dose of slowly-delivered paclitaxel (“low dose” group) were implanted in pig coronary arteries. “High dose” stented vessels developed wide-spread tissue necrosis, incomplete healing, late stent malapposition, and late stent thrombosis in 25 % of treated vessels. “Low dose” stented vessels developed minimal neointima, complete endothelialization and wound healing by 90 days, and no thrombotic complications. From rabbit and porcine data, it is clear that stent-based paclitaxel delivery may have a profound and durable effect, but that tissue dosimetry must be carefully contained within the therapeutic window. Pilot clinical trials including TAXUS I (using the NIR stent “low dose” profile described above) have demonstrated an astonishing effect on restenosis reduction in human coronaries. Furthermore, larger-scale trials will be needed to confirm the safety and efficacy of stent-based paclitaxel delivery and its applicability to more complex, “real world” clinical situations including bifurcation lesions, left main disease, the use of overlapping stents, and the potential need for extended anti-platelet therapy.

Comparison of gold-coated NIR stents with uncoated NIR stents in patients with coronary artery disease

Comparison of gold-coated NIR stents with uncoated NIR stents in patients with coronary artery disease

Randomized comparison of gold-coated NIR stents with uncoated NIR stents in patients with coronary artery disease

Randomized comparison of gold-coated NIR stents with uncoated NIR stents in patients with coronary artery disease

Predictors of clinical outcome following NIR stent implantation for coronary artery disease: analysis of the results of the First International New Intravascular Rigid-Flex Endovascular Stent Study (FINESS trial).

Patient and procedural characteristics associated with major adverse cardiac events following balloon angioplasty have been identified. Factors predictive of angiographic restenosis following coronary stent implantation have been reported, although patient variables associated with adverse clinical outcome are not well defined. HYPOTHESIS AND METHODS: To identify predictors of adverse clinical outcome following NIR stent implantation, clinical and angiographic characteristics of patients enrolled in the FINESS Trial were subjected to stepwise logistic regression analysis. From December 1995 through March 1996, NIR stent implantation was attempted in 255 patients (341 lesions) enrolled prospectively in a multicenter registry with broad entry criteria. On stepwise logistic regression analysis, the presence of multivessel disease, diabetes, and the total length of the stented segment were predictive of major adverse cardiac events during 6-month follow-up. For every 1 mm increase in stent length, the risk for the combined end point of death or myocardial infarction increased by 3%. Lesion length was not predictive of clinical events on multivariate analysis. Our data raise the possibility that an attempt to use shorter stents to cover significant stenoses, but not adjacent areas of visible narrowing, may improve outcome.

A randomized comparison of the value of additional stenting after optimal balloon angioplasty for long coronary lesions: Final results of the additional value of nir stents for treatment of long coronary lesions (ADVANCE) study

ObjectivesWe sought to investigate the clinical benefit of additional stent implantation after achieving an optimal result of balloon angioplasty (BA) in long coronary lesions (>20 mm). BackgroundLong coronary lesions are associated with increased early complications and late restenosis after BA. Stenting improves the early outcome, but stent restenosis is also related to both lesion length and stent length. MethodsA total of 437 patients with a single native lesion 20 to 50 mm in length were included and underwent BA, using long balloons matched to lesion length and vessel diameter (balloon/artery ratio 1.1) to achieve a diameter stenosis (DS) <30% by on-line quantitative coronary angiography (QCA). “Bail-out stenting” was performed for flow-limiting dissections or >50% DS. Patients in whom an optimal BA result was achieved were randomized to additional stenting (using NIR stents) or no stenting. The primary end point was freedom from major adverse cardiac events (MACE) at nine months, and core laboratory QCA was performed on serial angiograms. ResultsBailout stenting was necessary in 149 patients (34%) and was associated with a significantly increased risk of peri-procedural infarction (p < 0.02). Among the 288 randomized patients, the mean lesion length was 27 ± 9 mm, and the vessel diameter was 2.78 ± 0.52 mm. The procedural success rate was 90% for the 143 patients assigned to BA alone (control group), as compared with 93% in the 145 patients assigned to additional stenting (stent group), which resulted in a superior early minimal lumen diameter (0.54 mm, p < 0.001) and led to reduced angiographic restenosis (27% vs. 42%, p = 0.022). Freedom from MACE at nine months was 77% in both groups. ConclusionsA strategy of provisional stenting for long coronary lesions led to bailout stenting in one-third of patients, with a threefold increase in peri-procedural infarction. Additional stenting yielded a lower angiographic restenosis rate, but no reduction in MACE at nine months.

A Prospective, Randomized Comparison of Clinical Outcomes of the CrossFlex and NIR Stents in Coronary Intervention

Background and Objectives:This prospective single-center randomized clinical study was designed to evaluate the long-term angiographic and clinical outcomes of elective treatment using the Crossflex (coil stent) as compared with the NIR (tubular stent) in patients with native coronary artery disease. Subjects and Methods:104 patients with 107 de novo discrete coronary stenoses were randomly assigned to the NIR stent (54 coronary stenoses) or the Crossflex stent (53 coronary stenoses). Six-month follow-up angiograms were obtained in 83 patients with 86 lesions (80%). Clinical follow up was available in all patients and the period averaged 23.1±5.3 months in the Crossflex group and 23.1±6.2 months in the NIR group. Results:Procedural success was measured at 100% in both groups. There were no cases of stent thrombosis in either group. Although a higher loss index and more severe follow-up diameter stenosis occurred in the crossflex group, the angiographic restenosis rate was not significantly different in between the groups (35.0% for the Crossflex group versus 19.6% for the NIR group, p=0.11). The target lesion revascularization rate was also similar in both groups (13.5% for the Crossflex versus 14.8% for the NIR group, p=0.55). The two-year event free survival rate was not significantly different between the groups (70.8±8.3% in Crossflex group and 78.1± 6.6% in NIR group, p=0.36). Conclusion:In terms of the treatment of discrete native coronary artery disease, the angiographic and long-term clinical results of the Crossflex stent were not significantly different from those obtained with the NIR stent. (Korean Circulation J 2002;32(5):385-390)

Randomized comparison of J&J Crown stent versus NIR stent after routine coronary angioplasty

Background Coronary artery stents are used for the treatment of acute or threatening vessel occlusion complicating coronary angioplasty or for prevention of restenosis after angioplasty. The current randomized trial compared the procedural outcome and long-term patency of 2 different flexible stents in unselected lesion morphology. Methods The study population consisted of consecutive patients undergoing coronary angioplasty for symptomatic coronary artery disease followed by high-pressure stent implantation. The poststent treatment consisted of antiplatelet therapy. The primary hypothesis was an assumed restenosis rate of 30% in the group receiving NIR stents (Boston Scientific Europe SPRL, Parc Industriel de Petit-Rechain, Belgium) and a reduction of the restenosis rate (defined as >50% vessel diameter at follow-up) by 50% in the group undergoing J&J Crown stent (Cordis, Johnson & Johnson Interventional Systems, Warren, NJ) implantation: the restenosis rate and minimal luminal diameter at follow-up. Follow-up angiography was performed 6 months after the initial procedure. Results A total of 203 patients were randomized to receive either the J&J Crown stent (n = 103) or the NIR stent (n = 100). The procedural success was similar in both groups (96.1% vs 99% in the NIR stent group, respectively; P =.19). There were 4 cases of crossover from the J&J Crown to the NIR stent group. In one patient, stent implantation of either stent model did not succeed. One patient died from fulminant pulmonary embolism. Restenosis, defined as >50% diameter stenosis at follow-up 5.8 ± 1.3 months after the initial procedure occurred in 19 patients (18.4%) in the J&J Crown stent group compared with 22 patients (22.0%) in the NIR stent group (P =.42). There was a significantly higher rate of crossover from the J&J Crown stent to the NIR stent (3.9% vs 0%, respectively, P =.047), whereas reverse crossover did not occur. The one lesion in which NIR stent implantation was not successful had an extremely tortuous proximal part. This patient underwent only balloon angioplasty. Clinical events were rare during 6 months of follow-up and the incidence did not differ between both groups (nonfatal myocardial infarction: J&J Crown stent 1.0% vs 0% in the NIR stent group, P =.32; all-cause mortality: J&J Crown stent 1.0% vs 0% in the NIR stent group, P =.32). Conclusions There were no significant angiographic and clinical differences between the J&J Crown and NIR stents. Both stents had a similar procedural success rate, although the implantation of NIR stents was successful even in vessels in which previous attempts at J&J Crown stent placement had failed. (Am Heart J 2001;142:e8.)

Intravascular Ultrasound‐Guided Stenting in Long Lesions: An Insight into Possible Mechanisms of Restenosis and Comparison of Angiographic and Intravascular Ultrasound Data from the MUSIC and RENEWAL Trials

The high restenosis rates in long stents may be related to suboptimal stent deployment. In an attempt to understand the potential components associated with restenosis in long stents, this study compares angiographic and intravascular ultrasound (IVUS) data from the MUSIC and RENEWAL studies where IVUS was used to optimize stent deployment in short (< 15 mm) and long (> 20 mm) coronary lesions, respectively. The RENEWAL study, a randomized trial, compared the NIR stent and Wallstent in long (> 20 mm) coronary lesions and used on-line visual IVUS criteria to optimize stent expansion. Detailed analysis of IVUS data was performed off line. Angiographic and IVUS data from this study was compared to that from the MUSIC study. Initial stent deployment was deemed optimal by the operator after visual angiographic and IVUS assessment in 50 of 70 lesions. In the remaining 20 lesions further balloon inflations were required to optimize stent apposition that led to an average gain in minimal in-stent luminal area (MISA) of 15.9% (P < 0.01). Off-line IVUS data analysis showed that the number reaching "MUSIC criteria" for optimal stent deployment preredilatation was 8 (11.4%) of 70 and 14 (20%) of 70 postredilatation. The ratio of MISA/MRAprox (mean proximal reference area) was 0.69 in RENEWAL. At 6-month follow-up, the angiographic restenosis rate in RENEWAL was 36% and target lesion revascularization (TLR) rate was 7.8%, compared with MUSIC's 9.7% and 4.5%, respectively. In conclusion, angiographic assessment of stent deployment in long lesions is limited. On-line visual IVUS with further balloon inflations to improve stent apposition led to a significant gain in MISA, but the MISA/MRAprox ratio remained suboptimal. Therefore, suboptimal stent deployment due to constraint by lesion resistance may be an important mechanism underlying the high restenosis rates in long stents.