Polymer-based paclitaxel-eluting stents reduce in-stent neointimal tissue proliferation

Assessment of Mortality and Factors Affecting Outcome of Use of Paclitaxel-Coated Stents and Bare Metal Stents in Femoropopliteal PAD

The use of drug-coated devices in intravascular therapy is aimed at preventing neointimal hyperplasia caused by excessive proliferation of vascular smooth muscle and thereby restenosis. Although its use seemed initially promising, a recent publication has shown an increased risk of mortality with paclitaxel-coated devices, and there is an urgent need to reaffirm assessments of drug-eluting stents (DES). Objective: The aim of the study was to compare mortality and effectiveness of paclitaxel-coated stents and bare-metal stents (BMS) in the treatment of peripheral arterial disease (PAD) with long-term follow-up. Materials and methods: In a single center randomized study, 256 patients with PAD were treated intravascularly with stent implantation. Patients were randomized into two groups: the first (n = 126) were treated with DES, and the second (n = 130) were treated with BMS. The study included evaluation after the procedure, after about 6 months and 36 months. Co-morbidities, with risks for atherosclerosis, were analyzed in all patients. Patients were evaluated for clinical outcome, restenosis frequency, and safety (complications and total mortality). Results: Clinical benefit at the end of the investigation was statistically significantly better in the DES group compared with the BMS group: 85.7% versus 66.2% (p = 0.0003), respectively. Restenosis occurred significantly less frequently in patients with DES: 16.0% versus BMS: 35.0%, p = 0.012. There was no significant effect of comorbidities on the frequency of restenoses. There were no differences in all-cause mortality over the three years with paclitaxel and no-paclitaxel stents cohorts (8.7% versus 7.1%; long-rank p = 0.575). No association was found with mortality and treatment with DES or BMS. Conclusions: The use of paclitaxel-coated stents gave good clinical benefit and caused a significantly lower frequency of restenosis compared to bare-metal stents. The use of paclitaxel-coated stents did not increase mortality.

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

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

Numerical investigations of the haemodynamic changes associated with stent malapposition in an idealised coronary artery

The deployment of a coronary stent near complex lesions can sometimes lead to incomplete stent apposition (ISA), an undesirable side effect of coronary stent implantation. Three-dimensional computational fluid dynamics (CFD) calculations are performed on simplified stent models (with either square or circular cross-section struts) inside an idealised coronary artery to analyse the effect of different levels of ISA to the change in haemodynamics inside the artery. The clinical significance of ISA is reported using haemodynamic metrics like wall shear stress (WSS) and wall shear stress gradient (WSSG). A coronary stent with square cross-sectional strut shows different levels of reverse flow for malapposition distance (MD) between 0mm and 0.12 mm. Chaotic blood flow is usually observed at late diastole and early systole for MD=0mm and 0.12 mm but are suppressed for MD=0.06 mm. The struts with circular cross section delay the flow chaotic process as compared to square cross-sectional struts at the same MD and also reduce the level of fluctuations found in the flow field. However, further increase in MD can lead to chaotic flow not only at late diastole and early systole, but it also leads to chaotic flow at the end of systole. In all cases, WSS increases above the threshold value (0.5 Pa) as MD increases due to the diminishing reverse flow near the artery wall. Increasing MD also results in an elevated WSSG as flow becomes more chaotic, except for square struts at MD=0.06 mm.

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.

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.

Comparison of vascular remodeling in patients treated with sirolimus-versus zotarolimus-eluting stent following acute myocardial infarction

BACKGROUND

The differences in the vascular response to stent implantation or in the incidence of late acquired stent malapposition among different types of drug-eluting stents are not well known in patients with acute myocardial infarction (MI).

HYPOTHESIS

The pattern of vascular remodeling and degree of neointimal proliferation were different depending on the different types of drug-eluting stents.

METHODS

This study used intravascular ultrasound (IVUS) to investigate vascular remodeling in patients treated with implantation of sirolimus-eluting stents (SESs) vs zotarolimus-eluting stents (ZESs) following acute MI. The study population consisted of 100 patients with acute MI who were treated either with SES (n = 41) or ZES (n = 59) and underwent both poststenting and 9-month follow-up IVUS examination. Serial vascular changes surrounding stented segments were compared between SES- and ZES-treated lesions.

RESULTS

Percentage of neointimal volume obstruction at follow-up was significantly smaller in SES-treated compared to ZES-treated lesions (2.8 ± 7.1% vs 18.1 ± 15.7%, respectively; P < 0.001). However, positive vascular remodeling, which was defined as greater than 10% increase in external elastic membrane volume index (31.7% vs 10.2%, respectively, P = 0.007), and late acquired stent malapposition (12.0% vs 0%, respectively, P = 0.006 ) occurred more frequently in SES-treated than in ZES-treated lesions.

CONCLUSIONS

The pattern of vascular remodeling, including positive remodeling, late acquired stent malapposition, and degree of neointimal proliferation might be different depending on the different types of drug-eluting stents in patients with acute MI.

Paclitaxel-eluting stents reduce neointimal hyperplasia compared to bare metal stents in saphenous vein grafts: intravascular ultrasonography analysis of the SOS (Stenting of Saphenous Vein Grafts) trial

AIMS

To compare the intravascular ultrasonography (IVUS) findings between saphenous vein grafts (SVG) treated with paclitaxel-eluting stents (PES) vs. bare metal stents (BMS) in the Stenting Of Saphenous Vein Grafts (SOS) trial.

METHODS AND RESULTS

Of the 80 SOS trial patients, 38 had both baseline and follow-up IVUS examination and were included in this substudy: 17 patients received 28 BMS in 26 lesions and 21 patients received 30 PES in 28 lesions. Quantitative IVUS analysis was performed to determine the volume of in-stent neointimal hyperplasia (NIH) - defined as the difference between stent volume and lumen volume in the stented segments. Baseline characteristics were similar between patients who did and did not undergo baseline and follow-up IVUS. Patients receiving BMS and PES had similar stent and lumen volumes immediately after stenting. At 12-month follow-up, compared to BMS, PES-treated lesions had significantly less NIH volume (3.4 vs. 21.9 mm³, p<0.001) and neointima hyperplasia progression (1.6 vs. 17.1 mm³, p<0.001). No significant differences were seen in the 5 mm segment proximal and distal to the stent.

CONCLUSIONS

Compared to BMS, use of PES in SVG lesions is associated with significantly lower NIH formation, which may help explain the improved clinical outcomes with PES in these lesions.

Intravascular Ultrasound Results From the NEVO ResElution-I Trial

Background—

The NEVO sirolimus-eluting stent (NEVO SES) is a novel cobalt-chromium stent combining sirolimus release from reservoirs with bioabsorbable polymer to reduce spatial and temporal polymer exposure. The aim of this study was to assess the arterial response to the NEVO SES in a randomized, blinded comparison versus the surface-coated TAXUS Liberte paclitaxel-eluting stent (TAXUS Liberté PES) in human native coronary lesions using intravascular ultrasound (IVUS).

Methods and Results—

The NEVO ResElution-I IVUS substudy enrolled 100 patients (1:1 randomization). In addition to standard IVUS variables, uniformity of neointimal distribution within stents was evaluated in 3 dimensions by computing mean neointimal thickness within 12 equally spaced radial sectors on every 1-mm cross section along the stented segment. The NEVO SES showed significantly less neointimal proliferation (neointimal obstruction: 5.5±11.0% versus 11.5±9.7%, P =0.02), resulting in less late lumen area loss and smaller maximum cross-sectional narrowing at 6 months. The absolute variability of neointima distribution, assessed by the standard deviation of neointimal thickness within each stent, was significantly reduced with the NEVO SES compared with the TAXUS Liberté PES(0.04±0.04 mm versus 0.10±0.07 mm, P <0.0001). TAXUS Liberté PES showed significantly greater positive vessel remodeling than the NEVO SES (Δvessel volume index: 1.30±1.36 mm 3 /mm versus 0.36±0.63 mm 3 /mm, respectively, P =0.003).

Conclusions—

The NEVO SES with focal release of sirolimus from reservoirs achieved significantly greater and more consistent suppression of neointimal hyperplasia than the surface-coated TAXUS Liberté PES. This was associated with less positive remodeling and no increased morphological or morphometric abnormalities surrounding the stent or at the stent margins.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00714883.

Assessment of drug-eluting stents and bioresorbable stents by grayscale IVUS and IVUS-based imaging modalities

Grayscale IVUS and IVUS-based imaging modalities during the last years have become useful in the assessment not only of drug eluting stent, but also of new bioresorbable vascular scaffolds. Although IVUS resolution is not sufficient for determining stent coverage (optical coherence tomography is the gold standard), serial IVUS can measure intimal hyperplasia, assess acute and late incomplete stent apposition, detect the presence and persistence of edge dissections, study edge effects and look for causes of restenosis and thrombosis. In addition other IVUS-based imaging modalities, such as IVUS-VH, iMAP or palpography, can be used to study the serial compositional and mechanical changes of the plaque behind stent struts and also to follow the bioresorption of the new bioresorbable scaffolds, analyzing the backscattering signal coming from the polymeric struts. This review details and evaluates grayscale IVUS and IVUS-based techniques findings in clinical trials, highlighting the usefulness of these imaging modalities in the study of drug eluting stents and bioresorbable vascular scaffold.

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.

Long-term impact of routinely detected early and late incomplete stent apposition: an integrated intravascular ultrasound analysis of the TAXUS IV, V, and VI and TAXUS ATLAS workhorse, long lesion, and direct stent studies

OBJECTIVES

We sought to determine the 2-year impact of early and late-acquired incomplete stent apposition (ISA) on clinical events.

BACKGROUND

The late clinical impact of early or late-acquired ISA in bare-metal stents (BMS) and TAXUS stents (Boston Scientific, Natick, Massachusetts) is debatable.

METHODS

We evaluated 1,580 patients enrolled in the intravascular ultrasound (IVUS) substudies of TAXUS IV, V, VI and TAXUS-ATLAS WH, LL, and DS trials.

RESULTS

There were 96 cases of early ISA in 26 (7.2%) BMS patients, 35 (9.7%) TAXUS Express patients (p = 0.28 vs. BMS), and 35 (7.3%) TAXUS Liberté patients (p = 0.21 vs. TAXUS Express, and p = 1.00 vs. BMS). Major adverse cardiovascular events were similar at 9 months in patients with early ISA versus control subjects with no ISA for BMS (3.8% vs. 15.2%, p = 0.13) and for TAXUS (11.6% vs. 8.8%, p = 0.45). There was no impact of early ISA on stent thrombosis. At 9-month follow-up, there were 36 cases of late-acquired ISA in 7 (2.7%) BMS patients, 17 (3.1%) patients with TAXUS slow-release (TAXUS Express or TAXUS Liberté), and 12 (15.4%) patients receiving TAXUS moderate-release. Over 2 ensuing years, major adverse cardiovascular events were similar in patients with late-acquired ISA versus control subjects with no ISA for BMS (14.3% vs. 7.9%, p = 0.54), TAXUS (overall, 8.3% vs. 8.1% p = 0.87), or TAXUS slow-release formulation (0% vs. 7.9%, p = 0.28). There was no impact of late-acquired ISA on stent thrombosis.

CONCLUSIONS

Neither routinely detected acute ISA nor routinely detected late-acquired ISA in BMS or TAXUS patients was associated with adverse clinical events over long-term follow-up.

Comparison of everolimus- versus paclitaxel-eluting stents implanted in patients with diabetes mellitus as evaluated by three-dimensional intravascular ultrasound analysis

Previous reports have shown the advantage of paclitaxel compared to limus-derivative drugs for the treatment of diabetics. A total of 109 diabetics (115 lesions) treated with everolimus-eluting stents (EESs, n = 58) or paclitaxel-eluting stents (PESs, n = 55) undergoing 8 to 9 months of follow-up 3-dimensional intravascular ultrasound examinations were enrolled. In addition to the standard intravascular ultrasound parameters, the percentage of neointimal volume (neointimal volume/stent volume) and maximum percentage of cross-sectional narrowing (neointimal area/stent area) was calculated. EESs showed a lower percentage of neointimal volume (7.2 +/- 7.1% vs 11.7 +/- 11.0%; p = 0.01) and maximum percentage of cross-sectional narrowing (22.5 +/- 16.3% vs 29.4 +/- 19.2%; p = 0.04) than PESs. One case of severe narrowing (lesions with maximum percentage of cross-sectional narrowing >60%) in the EES group developed and 6 cases in the PESs group (p = 0.05). The EESs showed no serial changes for vessel or peri-stent plaque during the follow-up period, and PESs showed significant increases in vessel and peri-stent plaque. PESs showed significantly greater peri-stent plaque increase, with a tendency toward greater vessel enlargement than EESs. Late acquired incomplete stent apposition was observed in 2 PES cases. The major adverse cardiac event rate was comparable < or =2 years. In conclusion, EESs showed greater neointimal suppression without significant vessel expansion than PESs in diabetic patients. In this small cohort, no significant differences were observed in the major adverse cardiac event rate < or =2 years.

Comparison of optical coherence tomography and intravascular ultrasound for the assessment of in-stent tissue coverage after stent implantation

AIMS

At present there exists no direct comparative data for the detection of in-stent tissue coverage as assessed by intravascular ultrasound (IVUS) and optical coherence tomography (OCT) in clinical settings. To explore this subject, we investigated the correlation between the IVUS and OCT measurements derived from a contemporary population.

METHODS AND RESULTS

The present study includes 20 patients who had stents imaged at a six months follow-up with both IVUS and OCT, acquired with an automated pull-back. Off-line analyses were done by an independent validated Core-Lab (RHR, Rome, Italy). Measurements of stent length obtained by IVUS and OCT were 16.3+/-3.0 mm and 16.2+/-3.8 mm respectively (p=0.82) and were similar to nominal length (16.3+/-3.3 mm). Luminal area in the OCT image set was lower than that obtained in the corresponding IVUS image set (3.83+/-1.60 mm2 vs 4.05+/-1.44 mm2, p<0.001), while stent area was significantly higher when measured by OCT (6.61+/-1.39 mm2 vs 6.17+/-1.07 mm2, p<0.001). The percentage of tissue coverage measured by IVUS was lower than that measured in the corresponding OCT image sets (35.5+/-16.4% vs 43.4+/-16.1%, p<0.001). Correlation coefficients were high for repeated OCT measurements by two different observers (r=0.99).

CONCLUSIONS

OCT can quantify in-stent coverage and detect strut healing with high reproducibility. IVUS tends to underestimate the percentage of in-stent tissue coverage as compared to OCT.

SPIRIT III JAPAN versus SPIRIT III USA: a comparative intravascular ultrasound analysis of the everolimus-eluting stent

The aim of this study was to evaluate the vascular response after everolimus-eluting stent (EES) implantation in the SPIRIT III Japan Registry (JAPAN) compared to EES implantation in the SPIRIT III United States (USA) trial using serial intravascular ultrasound (IVUS) analysis. Data were obtained from the JAPAN and the randomized EES arm of the USA trial. Serial (postprocedure and 8-month follow-up) IVUS analysis was available in 199 lesions (JAPAN 82, USA 117) of 183 patients (JAPAN 73, USA 110). Although no difference was observed in vessel size in the reference segment between the 2 groups, postprocedure minimum lumen area and stent volume index were significantly greater in the JAPAN arm (minimum lumen area 5.8 +/- 2.2 vs 5.1 +/- 1.5 mm(2), p = 0.03; stent volume index 7.0 +/- 2.4 vs 6.3 +/- 1.7 mm(3)/mm, p = 0.03). Postprocedure incomplete stent apposition (ISA) was less frequently observed in the JAPAN arm (15.9% vs 33.3%, p = 0.006), possibly related to higher maximum balloon pressure and/or more postdilatation without excess tissue prolapse or edge dissection. In the JAPAN arm, percent neointimal obstruction and maximum percent cross-sectional narrowing were significantly lower at 8-month follow-up (percent neointimal obstruction 3.5 +/- 4.2% vs 6.8 +/- 6.4%, p = 0.0004). Late acquired ISA was infrequent in the 2 arms. In conclusion, comparative IVUS analysis between the JAPAN and USA arms showed more optimal stent deployment in the JAPAN arm as evidenced by the lower incidence of postprocedure ISA and larger minimum lumen area after the procedure. Moreover, there was less neointimal hyperplasia in patients with EES implants from the JAPAN arm compared to the USA arm.

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.

An optical coherence tomography study of a biodegradable vs. durable polymer-coated limus-eluting stent: a LEADERS trial sub-study

AIMS

Incomplete endothelialization has been found to be associated with late stent thrombosis, a rare but devastating phenomenon, more frequent after drug-eluting stent implantation. Optical coherence tomography (OCT) has 10 times greater resolution than intravascular ultrasound and thus appears to be a valuable modality for the assessment of stent strut coverage. The LEADERS trial was a multi-centre, randomized comparison of a biolimus-eluting stent (BES) with biodegradable polymer with a sirolimus-eluting stent (SES) using a durable polymer. This study sought to evaluate tissue coverage and apposition of stents using OCT in a group of patients from the randomized LEADERS trial.

METHODS AND RESULTS

Fifty-six consecutive patients underwent OCT during angiographic follow-up at 9 months. OCT images were acquired using a non-occlusive technique at a pullback speed of 3 mm/s. Data were analysed using a Bayesian hierarchical random-effects model, which accounted for the correlation of lesion characteristics within patients and implicitly assigned analytical weights to each lesion depending on the number of struts observed per lesion. Primary outcome was the difference in percentage of uncovered struts between BESs and SESs. Twenty patients were included in the analysis in the BES group (29 lesions with 4592 struts) and 26 patients in the SES group (35 lesions with 6476 struts). A total of 83 struts were uncovered in the BES group and 407 out of 6476 struts were uncovered in the SES group [weighted difference -1.4%, 95% confidence interval (CI) -3.7 to 0.0, P = 0.04]. Results were similar after adjustment for pre-procedure lesion length, reference vessel diameter, number of implanted study stents, and presence of stent overlap. There were three lesions in the BES group and 15 lesions in the SES group that had > or =5% of all struts uncovered (difference -33.1%, 95% CI -61.7 to -10.3, P < 0.01).

CONCLUSION

Strut coverage at an average follow-up of 9 months appears to be more complete in patients allocated to BESs when compared with SESs. The impact of this difference on clinical outcome and, in particular, on the risk of late stent thrombosis is yet to be determined.

Early- and long-term intravascular ultrasound and angiographic findings after bioabsorbable magnesium stent implantation in human coronary arteries

OBJECTIVES

This study aimed to evaluate the degradation rate and long-term vascular responses to the absorbable metal stent (AMS).

BACKGROUND

The AMS demonstrated feasibility and safety at 4 months in human coronary arteries.

METHODS

The PROGRESS-AMS (Clinical Performance and Angiographic Results of Coronary Stenting) was a prospective, multicenter clinical trial of 63 patients with coronary artery disease who underwent AMS implantation. Angiography and intravascular ultrasound (IVUS) were conducted immediately after AMS deployment and at 4 months. Eight patients who did not require repeat revascularization at 4 months underwent late angiographic and IVUS follow-up from 12 to 28 months.

RESULTS

The AMS was well-expanded upon deployment without immediate recoil. The major contributors for restenosis as detected by IVUS at 4 months were: decrease of external elastic membrane volume (42%), extra-stent neointima (13%), and intra-stent neointima (45%). From 4 months to late follow-up, paired IVUS analysis demonstrated complete stent degradation with durability of the 4-month IVUS indexes. The neointima was reduced by 3.6 +/- 5.2 mm(3), with an increase in the stent cross sectional area of 0.5 +/- 1.0 mm(2) (p = NS). The median in-stent minimal lumen diameter was increased from 1.87 to 2.17 mm at long-term follow-up. The median angiographic late loss was reduced from 0.62 to 0.40 mm by quantitative coronary angiography from 4 months to late follow-up.

CONCLUSIONS

Intravascular ultrasound imaging supports the safety profile of AMS with degradation at 4 months and maintains durability of the results without any early or late adverse findings. Slower degradation is warranted to provide sufficient radial force to improve long-term patency rates of the AMS.

Serial intravascular ultrasound analysis of peri-stent remodeling and proximal and distal edge effects after sirolimus-eluting or paclitaxel-eluting stent implantation in patients with diabetes mellitus

Patients with diabetes have an increased risk of in-stent restenosis after coronary stent implantation. Serial intravascular ultrasound was used to study chronic arterial responses and edge effects after implantation of Cypher (Cordis, Johnson & Johnson, Miami Lakes, Florida) or Taxus (Boston Scientific, Maple Grove, Minnesota) stents in diabetic patients. Seventy-four diabetic patients were randomly assigned to Cypher or Taxus stent implantation. Intravascular ultrasound of 5-mm long segments immediately proximal and distal to the stent was performed after the procedure and at the 8-month follow-up. The increase in peri-stent external elastic membrane (EEM) volume was more pronounced in the Taxus group (292.4 +/- 132.6 to 309.5 +/- 146.8 mm(3)) than in the Cypher group (274.4 +/- 137.2 to 275.4 +/- 140.1 mm(3); p = 0.005). Peri-stent plaque volume increased in the Taxus group (152.5 +/- 73.7 to 166.1 +/- 85.1 mm(3)), but was unchanged in the Cypher group (153.5 +/- 75.5 to 151.5 +/- 75.8 mm(3); p = 0.002). In proximal and distal reference segments, mean lumen area decreased within the entire 5-mm edge segment (proximal and distal) because of plaque progression (distal, 5.5 +/- 3.6 to 5.8 +/- 3.7 mm(2); p = 0.097; proximal, 8.1 +/- 2.7 to 8.7 +/- 2.9 mm(2); p = 0.006) without remodeling (change in EEM) in the Taxus group. Conversely, there were no significant changes in reference-segment EEM or plaque areas in the Cypher group. In conclusion, in diabetic patients, Taxus stent implantation was associated with increased (1) peri-stent EEM volume and peri-stent plaque, and (2) stent edge plaque progression accompanied by lumen reduction without remodeling. These findings were not seen in Cypher stents.

KIS protects against adverse vascular remodeling by opposing stathmin-mediated VSMC migration in mice

Vascular proliferative diseases are characterized by VSMC proliferation and migration. Kinase interacting with stathmin (KIS) targets 2 key regulators of cell proliferation and migration, the cyclin-dependent kinase inhibitor p27Kip1 and the microtubule-destabilizing protein stathmin. Phosphorylation of p27Kip1 by KIS leads to cell-cycle progression, whereas the target sequence and the physiological relevance of KIS-mediated stathmin phosphorylation in VSMCs are unknown. Here we demonstrated that vascular wound repair in KIS-/- mice resulted in accelerated formation of neointima, which is composed predominantly of VSMCs. Deletion of KIS increased VSMC migratory activity and cytoplasmic tubulin destabilizing activity, but abolished VSMC proliferation through the delayed nuclear export and degradation of p27Kip1. This promigratory phenotype resulted from increased stathmin protein levels, caused by a lack of KIS-mediated stathmin phosphorylation at serine 38 and diminished stathmin protein degradation. Downregulation of stathmin in KIS-/- VSMCs fully restored the phenotype, and stathmin-deficient mice demonstrated reduced lesion formation in response to vascular injury. These data suggest that KIS protects against excessive neointima formation by opposing stathmin-mediated VSMC migration and that VSMC migration represents a major mechanism of vascular wound repair, constituting a relevant target and mechanism for therapeutic interventions.

Impact of mild or moderate renal insufficiency on the intravascular ultrasonic analysis of chronic vascular response to paclitaxel-eluting and bare-metal stents (from the TAXUS IV, V, and VI trials)

The presence of even mild renal insufficiency is usually associated with an increased rate of cardiovascular events after coronary stenting. The aim of this study was to evaluate the impact of mild to moderate renal insufficiency on the chronic vascular responses to the implantation of paclitaxel-eluting stents (PES; Taxus) and bare-metal stents (BMS). In the TAXUS IV, TAXUS V, and TAXUS VI trials, patients with serum creatinine levels >2.0 mg/dl were excluded. In the present analysis, 816 patients with serum creatinine levels <or=2.0 mg/dl had intravascular ultrasound images acquired after the procedures and/or at 9-month follow-up (406 with PES, 410 with BMS). Patients were stratified by level of creatinine clearance (Ccr; group 1: Ccr <40; group 2: 40 <or=Ccr <60; group 3: 60 or/=Ccr <80; group 4: Ccr >or=80 ml/min/1.73 m(2)). For all levels of Ccr, patients with PES compared with those with BMS had less intimal hyperplasia area (group 1: 0.97 +/- 0.98 vs 2.94 +/- 1.89; group 2: 0.94 +/- 0.86 vs 2.30 +/- 1.21; group 3: 0.99 +/- 1.02 vs 2.53 +/- 1.29; group 4: 0.87 +/- 0.95 vs 2.12 +/- 1.29 mm(2), all p values <0.0001) and greater increases in peristent plaque and media area (group 1: 0.90 +/- 0.98 vs -0.02 +/- 0.98 mm(2), p = 0.03; group 2: 0.57 +/- 1.43 vs 0.20 +/- 1.14 mm(2), p = 0.11; group 3: 1.20 +/- 1.95 vs 0.02 +/- 1.17, p <0.0001; group 4: 0.35 +/- 1.44 vs -0.19 +/- 1.08 mm(2), p = 0.08). Neointimal growth and vessel remodeling were not affected by variations in Ccr after either BMS or PES implantation over the range studied. The incidence of incomplete stent apposition at follow-up was lowest in patients with the greatest renal impairment after BMS and PES implantation. In conclusion, neointimal proliferation was less prominent and expansive vessel remodeling was more prominent after PES than BMS implantation, independent of the severity of renal dysfunction.

Safety and efficacy of overlapping sirolimus-eluting versus paclitaxel-eluting stents

BACKGROUND

The short-term and long-term safety and efficacy of paclitaxel versus sirolimus-overlapping drug-eluting stents (DES) is unknown. We sought to examine the clinical consequences of overlapping sirolimus versus paclitaxel DES.

METHODS

We reviewed catheterization reports from April 2003 to May 2005 for all patients who underwent percutaneous coronary revascularization with DES. All patients were followed-up for at least 1 year. Patients were included if they received only 2 single-type overlapping stent (eg, sirolimus-sirolimus) during the index procedure. The end points included early (inhospital and 30-day) and late composite of all-cause mortality, stent thrombosis, myocardial infarction, and target lesion revascularization.

RESULTS

A total of 282 individuals met our study criteria. Of these, 188 had sirolimus and 94 had paclitaxel-overlapping DES. There were 78 events for a median follow-up of 24 months for the composite end point. No statistically significant differences between overlapping sirolimus and paclitaxel DES were seen for inhospital, 30-day (16% vs 23%, respectively; P = .13), and long-term (25% vs 33%, respectively; P = .16) composite end points. In addition, in Kaplan-Meier and Cox proportional hazard analysis, no significant differences for the composite end point were noted.

CONCLUSIONS

In this analysis, there were no significant differences in safety or efficacy between the 2 types of overlapping DES. Trends toward more events with overlapping paclitaxel stents should be evaluated in an adequately powered randomized controlled trial.

Crush Stenting With Paclitaxel-Eluting or Sirolimus-Eluting Stents for the Treatment of Coronary Bifurcation Lesions

Two hundred forty-six patients with 252 bifurcation lesions were enrolled into a prospective, nonrandomized study to use paclitaxel-eluting or sirolimus-eluting stent for crush stenting in the treatment of coronary bifurcation lesions. Compared with the sirolimus-eluting stent group, the paclitaxel-eluting stent group had significantly higher mean late lumen and binary angiographic restenosis rates. Sirolimus-eluting stent versus paclitaxel-eluting stent recipients had significantly lower in-segment restenosis in the entire main vessel (15.7% vs 3.1%, P = .004), and simultaneous side branch and main vessel restenoses were solely detected in the paclitaxel-eluting stent group (11.9% vs 0%, P = .03). Target-lesion vessel revascularization and cumulative major adverse cardiac events rates were significantly higher in the paclitaxel-eluting versus the sirolimus-eluting stent group (17.99% vs 8.41%, P = .01; 19.4 vs 9.3%, P = .01; 23.6 vs 11.2%, P = .03). In this study with crush stenting, use of sirolimus-eluting stent, compared with paclitaxel-eluting stent, yielded significantly lower late lumen loss, restenosis, and revascularization rates, with comparable safety by 8-month follow-up.

Comparison of vascular response to zotarolimus-eluting stent versus sirolimus-eluting stent: intravascular ultrasound results from ENDEAVOR III

BACKGROUND

The purpose of this study was to investigate the vascular response of zotarolimus-eluting stent (ZES) and sirolimus-eluting stent (SES) using serial intravascular ultrasound (IVUS).

METHODS

Data were obtained from the Endeavor Drug-Eluting Coronary Stent System Versus the Center Siromlimus-Eluting Coronary Stent System in De Novo Native Coronary Artery Lesions (ENDEAVOR) III trial, a randomized study comparing ZES and SES for the treatment of de novo native coronary artery lesions. Serial (baseline and 8-month follow-up) IVUS was available in 258 patients (190 ZES, 68 SES).

RESULTS

At 8 months, ZES had greater percentage of neointimal volume index (ZES 1.1 +/- 0.8 mm3/mm vs SES 0.2 +/- 0.1 mm3/mm, P < .01), resulting in smaller lumen volume index (6.0 +/- 2.0 mm3/mm vs 7.0 +/- 2.1 mm3/mm, P < .05). Zotarolimus-eluting stents showed larger IVUS-detectable neointimal coverage over stent surface (50.2% vs 10.5%, P < .01) and greater mean neointimal thickness (0.19 +/- 0.07 mm vs 0.10 +/- 0.06 mm, P < .01). Zotarolimus-eluting stents had a significantly lower incidence of late-acquired incomplete stent apposition.

CONCLUSIONS

Zotarolimus-eluting stent is associated with a significantly greater amount of neointimal hyperplasia compared with SES. This amount of hyperplasia in ZES is distributed throughout the stent at 8-month follow-up.