Abstract
Background
The objective of this intravascular ultrasound (IVUS) analysis was to evaluate the vascular response of the thin-strut TAXUS Liberté stent compared with the otherwise identical TAXUS Express stent.
Methods and Materials
The TAXUS ATLAS and TAXUS ATLAS Long Lesion studies are nonrandomized trials comparing the thin-strut TAXUS Liberté stent to historical TAXUS Express controls from the TAXUS IV and TAXUS V trials. A total of 377 patients enrolled in the two TAXUS ATLAS studies were randomly selected for the IVUS subset and compared to 314 TAXUS Express IVUS controls.
Results
Despite increased lesion complexity in the TAXUS Liberté group, neointimal formation at 9 months was similar in both stents (TAXUS Liberté 13.8±11.0%; TAXUS Express 13.1±13.8%, P =.56). However, this neointima covered more of the overall stent in the TAXUS Liberté (67.9±32.5%) compared with the TAXUS Express (54.4±37.2%, P <.001), suggesting more uniform neointimal distribution. TAXUS Liberté also showed less pronounced negative remodeling at both stent edges and had significantly less (4.3% vs. 9.6%, P =.04) late incomplete stent apposition (ISA).
Conclusions
Despite identical polymer and drug release characteristic, the thin-strut TAXUS Liberté stent demonstrates improved neointimal coverage, better edge remodeling, and less late ISA vs. TAXUS Express, hereby highlighting the importance of the platform design for drug-eluting stents.
1
Introduction
The TAXUS Liberté stent (Boston Scientific Corporation, Natick, MA, USA) was developed using the TAXUS polymer-based, paclitaxel-eluting technology, applied to the Liberté stent platform. Liberté uses an identical polymer and paclitaxel release pattern, applied to thinner struts and more uniform radial elements than the earlier Express platform, thus improving deliverability, conformability, and potentially providing more homogeneous drug distribution . The successful transfer of the TAXUS technology to the advanced Liberté platform has been proven in the pivotal TAXUS ATLAS trial . Furthermore, in the TAXUS ATLAS SMALL VESSEL (SV) and TAXUS ATLAS LONG LESION trials, the new stent design has been associated with significantly reduced rates of restenosis in patients with small vessels and periprocedural MI in patients with long lesions . However, the underlying mechanisms for the improved clinical outcomes with TAXUS Liberté are not clearly understood. The current integrated IVUS analysis combined data from the TAXUS ATLAS and TAXUS ATLAS LL studies to obtain a deeper understanding of the vascular response to TAXUS Liberté implantation. The objective of this analysis was to evaluate the effect of the TAXUS Liberté thin-strut stent design with uniform radial elements on neointima formation and stent coverage as compared with that of the TAXUS Express stent with otherwise identical polymer and drug release kinetic.
2
Methods
2.1
Device description
The TAXUS Liberté stent (Boston Scientific) consists of a balloon expandable Liberté stent with a poly(styrene- b -isobutylene- b -styrene) (SIBS) polymer coating containing 1 μg/mm 2 of paclitaxel in a slow-release formulation. Drug dosing and release kinetics are identical to those of the TAXUS Express stent. Both stents are made from 316L stainless steel, but the Liberté platform has thinner struts (0.0038 in. or 0.097 mm) and more uniform strut geometry than the Express platform (0.0052 in. or 0.132 mm). Furthermore, the TAXUS Liberté stent is available in three models to provide more consistent stent-to-artery ratios in small (2.25–2.50 mm), workhorse (2.75–3.50 mm), and large vessel (4.0 mm) diameters. Fig. 1 demonstrates the tissue coverage of an explanted TAXUS Liberté stent from a rabbit iliac artery as determined by scanning electron microscopy.
2.2
Study protocols
The TAXUS ATLAS and TAXUS ATLAS LL trials are prospective, multicenter nonrandomized trials using historical controls treated with the TAXUS Express stent in the TAXUS IV and TAXUS V trials. The study protocols were approved by local ethics review committees, and all patients provided written informed consent prior to their enrollment.
A summary of the TAXUS ATLAS and TAXUS ATLAS LL study designs is presented in Table 1 . Inclusion and exclusion criteria were similar to those for the TAXUS IV and V studies . Eligible patients were 18 years or older undergoing percutaneous coronary intervention of a single de novo lesion in a native coronary artery in a patient with a left ventricular ejection fraction of ≥25%. Patients within 72 h of a myocardial infarction were excluded. Angiographic exclusion criteria prohibited treatment of left main, ostial, or bifurcation lesions; total occlusion or a thrombus containing vessel; severe or moderate lesion calcification, arterial tortuosity, or a lesion on an excessive bend. Per protocol enrollment occurred after successful treatment of a nontarget lesion (if applicable), but before advancing a guide wire across the target lesion.
| TAXUS ATLAS | TAXUS ATLAS Long Lesion | |
|---|---|---|
| Study design | Single-arm, historically controlled | |
| Investigative sites | 61 sites in North America and Asia Pacific | 24 sites in North America and Asia Pacific |
| Patients (intent-to-treat) | 871 | 150 |
| Reference vessel diameter | ≥2.5–≤4.0 mm | ≥2.7–≤4.0 mm |
| Lesion length | ≥10–≤28 mm | ≥26–≤34 mm |
| Control group | TAXUS Express; derived (case-matched) from TAXUS IV and TAXUS V randomized trials | |
| Primary end point | 9-month target vessel revascularization | 9-month % diameter stenosis (analysis segment) |
| IVUS Core laboratory | Washington Hospital Center (MedStar Health Research Institute), Washington, DC | |
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