Propensity-matched patient-level comparison of the TAXUS Liberté and TAXUS element (ION) paclitaxel-eluting stents

Innovations in Vascular Repair from Mechanical Intervention to Regenerative Therapies

BACKGROUND

Vascular diseases, including atherosclerosis and thrombosis, are leading causes of morbidity and mortality worldwide, often resulting in vessel stenosis that impairs blood flow and leads to severe clinical outcomes. Traditional mechanical interventions, such as balloon angioplasty and bare-metal stents, provided initial solutions but were limited by restenosis and thrombosis. The advent of drug-eluting stents improved short-term outcomes by inhibiting vascular smooth muscle cell proliferation, however, they faced challenges including delayed reendothelialization and late-stage thrombosis.

METHODS

This review highlights the progression from mechanical to biological interventions in treating vascular stenosis and underscores the need for integrated approaches that combine mechanical precision with regenerative therapies.

RESULTS

To address long-term complications, bioresorbable stents were developed to provide temporary scaffolding that gradually dissolves, yet they still encounter challenges with mechanical integrity and optimal degradation rates. Consequently, emerging therapies now focus on biological approaches, such as gene therapy, extracellular vesicle treatments, and cell therapies, that aim to promote vascular repair at the cellular level. These strategies offer the potential for true vascular regeneration by enhancing endothelialization, modulating immune responses, and stimulating angiogenesis.

CONCLUSION

Integrating mechanical precision with regenerative biological therapies offers a promising future for treating vascular stenosis. A comprehensive approach combining these modalities could achieve sustainable vascular health.

Impact of Coronary Stent Architecture on Clinical Outcomes: Do Minor Changes in Stent Architecture Really Matter?

Introduction

The objective of this study was to compare the accumulated clinical outcomes of two Malaysian all-comers populations, each treated with different polymer-free sirolimus-eluting stents (PF-SES) of similar stent design.

Methods

The Malaysian subpopulation of two all-comers observational studies based on the same protocol (ClinicalTrials.gov Identifiers: NCT02629575 and NCT02905214) were combined and compared to a Malaysian-only cohort which was treated with a later-generation PF-SES. The PF-SES’s used differed only in their bare-metal backbone architecture, with otherwise identical sirolimus coating. The primary endpoint was the accumulated target lesion revascularization (TLR) rate at 12 months. The rates of major adverse cardiac events (MACE), stent thrombosis (ST) and myocardial infarction (MI) were part of the secondary endpoints.

Results

A total of 643 patients were treated with either the first-generation PF-SES (413 patients) or second-generation PF-SES (230 patients). Patient demographics were similar in terms of age (p = 0.744), male gender (0.987), diabetes mellitus (p = 0.293), hypertension (p = 0.905) and acute coronary syndrome (ACS, 44.8% vs. 46.1%, p = 0.752) between groups. There were no differences between treatment groups in terms of lesion length (20.8 ± 7.3 mm vs. 22.9 ± 7.9, p = 0.111) or vessel diameter (2.87 ± 0.39 vs. 2.93 ± 0.40, p = 0.052) despite numerically smaller diameters in the first-generation PF-SES group. The second-generation PF-SES tended to have more complex lesions as characterized by calcification (10.3% vs. 16.2%, p = 0.022), severe tortuosity (3.5% vs. 6.9%, p = 0.041) and B2/C lesions (49.2% vs. 62.8%, p < 0.001). The accumulated TLR rates did not differ significantly between the first- and second-generation PF-SES (0.8% vs. 0.9%, p = 0.891). The accumulated MACE rates were not significantly different (p = 0.561), at 1.5% (6/413) and 2.2% (5/230), respectively.

Conclusions

Modifications in coronary stent architecture which enhance the radial strength and radiopacity without gross changes in strut thickness and design do not seem to impact clinical outcomes.

Clinical Trial Registration

ClinicalTrials.gov Identifiers: NCT02629575 and NCT02905214.

Endovascular Metal Devices for the Treatment of Cerebrovascular Diseases

Cerebrovascular disease involves various medical disorders that obstruct brain blood vessels or deteriorate cerebral circulation, resulting in ischemic or hemorrhagic stroke. Nowadays, platinum coils with or without biological modification have become routine embolization devices to reduce the risk of cerebral aneurysm bleeding. Additionally, many intracranial stents, flow diverters, and stent retrievers have been invented with uniquely designed structures. To accelerate the translation of these devices into clinical usage, an in-depth understanding of the mechanical and material performance of these metal-based devices is critical. However, considering the more distal location and tortuous anatomic characteristics of cerebral arteries, present devices still risk failing to arrive at target lesions. Consequently, more flexible endovascular devices and novel designs are under urgent demand to overcome the deficiencies of existing devices. Herein, the pros and cons of the current structural designs are discussed when these devices are applied to the treatment of diseases ranging broadly from hemorrhages to ischemic strokes, in order to encourage further development of such kind of devices and investigation of their use in the clinic. Moreover, novel biodegradable materials and drug elution techniques, and the design, safety, and efficacy of personalized devices for further clinical applications in cerebral vasculature are discussed.

The effect of mechanical loads on the degradation of aliphatic biodegradable polyesters

Aliphatic biodegradable polyesters have been the most widely used synthetic polymers for developing biodegradable devices as alternatives for the currently used permanent medical devices. The performances during biodegradation process play crucial roles for final realization of their functions. Because physiological and biochemical environment in vivo significantly affects biodegradation process, large numbers of studies on effects of mechanical loads on the degradation of aliphatic biodegradable polyesters have been launched during last decades. In this review article, we discussed the mechanism of biodegradation and several different mechanical loads that have been reported to affect the biodegradation process. Other physiological and biochemical factors related to mechanical loads were also discussed. The mechanical load could change the conformational strain energy and morphology to weaken the stability of the polymer. Besides, the load and pattern could accelerate the loss of intrinsic mechanical properties of polymers. This indicated that investigations into effects of mechanical loads on the degradation should be indispensable. More combination condition of mechanical loads and multiple factors should be considered in order to keep the degradation rate controllable and evaluate the degradation process in vivo accurately. Only then can the degradable devise achieve the desired effects and further expand the special applications of aliphatic biodegradable polyesters.

Preparation of Polymeric Prodrug Paclitaxel-Poly(lactic acid)-b-Polyisobutylene and Its Application in Coatings of a Drug Eluting Stent

To develop a novel biodegradable and quite adhesive coating material for fabricating a paclitaxel (PTX)-containing eluting stent, herein, we report two kinds of drug eluting stent (DES) materials. One of them is a prodrug, PTX end-capped poly(lactic acid)-b-polyisobutylene (PTX-PLA-b-PIB) diblock copolymer, which possesses favorable biodegradability and biocompatibility. The other is a mixture of PIB-b-PLA diblock copolymer and PTX. PIB-b-PLA was synthesized via the ring-opening polymerization (ROP) using hydroxyl-terminated polyisobutylene (PIB-OH) as the initiator, while the PTX-PLA-b-PIB prodrug was prepared through a combination of ROP and Cu(I)-catalyzed azide-alkyne cycloaddition "click" reaction. The chemical structures and compositions as well as the molecular weights and molecular weight distributions of these copolymers have been fully characterized by (1)H nuclear magnetic resonance, Fourier transform infrared, and gel permeation chromatography measurements. The thermal degradation behavior and glass transition temperature (Tg) of the copolymers were studied by thermogravimetric analysis and differential scanning calorimetry, respectively. The solutions of PTX-PLA-b-PIB and the PIB-b-PLA/PTX mixture were separately coated onto the bare metal stents to form the PTX-containing DES. Subsequently, the surface structures and morphologies of the bare stent and DES were studied by atomic force microscopy and scanning electron microscopy, respectively. The in vitro release of PTX from these stents was conducted in a buffer medium (PBS 7.4) at 37 °C. The results showed that the coating formed by a blend of PTX-PLA-b-PIB, PIB-b-PLA, and PTX yielded a release that was better sustained than those of the individual PTX-PLA-b-PIB prodrug or PIB-b-PLA/PTX mixture. MTT assays demonstrated that the stent coated with PTX-PLA-b-PIB displayed a cytotoxicity lower than that of the PIB-b-PLA/PTX mixed layer, and the biocompatibility of coatings can be effectively improved by the prodrug.

Longitudinal stent deformation: a retrospective analysis of frequency and mechanisms

AIMS

Modern drug-eluting stents are constructed with thin struts and are easy to deliver and highly conformable. However, although innovative designs have enabled maintenance of radial strength, longitudinal strength may be lower with these stents and there have been recent reports of longitudinal stent compression of ostially deployed stents. We report the experience in our centre on longitudinal stent deformation and explore mechanisms of this complication and its frequency with various drug-eluting stent platforms.

METHODS AND RESULTS

Nine cases of longitudinal stent deformation were identified over a four year period representing 0.2% of cases and affected 0.097% of stents deployed. There were several mechanisms for this complication including compression by post-dilatation balloons, guide catheter extensions and proximal embolic protection devices. The rate of stent deformation varied from 0% in several stent types to 0.86% in the case of the Promus Element stent. There was one case of late stent thrombosis attributable to longitudinal stent deformation.

CONCLUSIONS

Longitudinal stent deformation can occur secondary to a variety of mechanisms and identification is important as, left untreated, it may be associated with a risk of stent thrombosis. Although seen with several different stents, in our series it was more commonly observed with the Promus Element stent.