Focus on STENTYS® Xposition S Self-Apposing® stent: a review of available literature

Shortened dual antiplatelet therapy in contemporary percutaneous coronary intervention era

Percutaneous coronary intervention with stenting is followed by a duration of dual antiplatelet therapy (DAPT) to reduce stent thrombosis and avoid target lesion failure. The period of DAPT recommended in international guidelines following drug-eluting stent implantation is 12 mo for most patients with acute coronary syndrome, and 6 mo for patients with chronic coronary syndrome or high bleeding risk. The new generation of drug-eluting stents have metallic platforms with thinner struts, associated with significantly less stent thrombosis. Shortened DAPT has been investigated with these stents, with evidence from randomised clinical trials for some individual stents showing non-inferior safety and efficacy outcomes. This has to be balanced by the effect of DAPT on secondary prevention of systemic cardiovascular disease especially in high-risk populations. This review will outline the current evidence for individual stents with regards to DAPT duration for both acute coronary syndrome and chronic coronary syndrome and discuss further directions for research and personalised medicine in this contemporary percutaneous coronary intervention era.

Design of Self-Expanding Auxetic Stents Using Topology Optimization

Implanting stents is the most efficient and minimally invasive technique for treating coronary artery diseases, but the risks of stent thrombosis (ST) and in-stent restenosis (IRS) hamper the healing process. There have been a variety of stents in market but dominated by ad hoc design motifs. A systematic design method that can enhance deliverability, safety and efficacy is still in demand. Most existing designs are focused on patient and biological factors, while the mechanical failures related to stenting architectures, e.g., inadequate stent expansion, stent fracture, stent malapposition and foreshortening, are often underestimated. With regard to these issues, the self-expanding (SE) stents may perform better than balloon-expandable (BE) stents, but the SE stents are not popular in clinic practice due to poor deliverability, placement accuracy, and precise match of the stent size and shape to the vessel. This paper addresses the importance between stent structures and clinic outcomes in the treatment of coronary artery disease. First, a concurrent topological optimization method will be developed to systematically find the best material distribution within the design domain. An extended parametric level set method with shell elements is proposed in the topology optimization to ensure the accuracy and efficiency of computations. Second, the auxetic metamaterial with negative Poisson’s ratio is introduced into the self-expanding stents. Auxetics can enhance mechanical properties of structures, e.g., fracture toughness, indentation and shear resistance and vibration energy absorption, which will help resolve the drawbacks due to the mechanical failures. Final, the optimized SE stent is numerically validated with the commercial software ANSYS and then prototyped using additive manufacturing techniques. Topological optimization gives a rare opportunity to exploiting the unique advantages of additive manufacturing. Hence, the topologically optimized auxetic architectures will provide a new solution for developing novel stenting structures, especially conductive to self-expanding SE stents. The new design will overcome the limitations of conventional SE stents associated with mechanical structures while maintain their valuable features, to help reduce the occurrence of ST and ISR and benefit the clinic practice in treating coronary heart disease.

Comparison of Contemporary Drug-eluting Coronary Stents - Is Any Stent Better than the Others?

Percutaneous coronary intervention (PCI) with implantation of a metallic drug-eluting stent (DES) is the mainstay of treatment in patients with significant coronary artery disease or acute coronary syndromes. DESs comprise a metallic platform and an anti-proliferative drug, usually released from a polymer coating. A wide range of DESs, differing in platform, polymer or drug, are currently available for clinical use. Although there are significant differences in the physical, biological and pharmacological properties of contemporary DESs, it remains unclear whether these impact meaningfully on clinical outcomes for patients undergoing PCI. Numerous randomised clinical trials have compared DESs in recent years, but these trials are typically designed to show non-inferiority, rather than superiority. Data from meta-analyses have helped to study this in larger populations, but have limitations. Improvement in stent design continues and ongoing work is exploring the effects of new innovations as well as gathering further data on existing devices. This review explores the development, properties and clinical efficacy of current-generation DESs, comparing different types where possible, whilst identifying areas of further work.