Five-year clinical follow-up of the STENTYS self-apposing stent in complex coronary anatomy: a single-centre experience with report of specific angiographic indications

The Randomized, Multicenter, Open-Label, Controlled POLBOS 3 Trial Comparing Regular Drug-Eluting Stents and the Sirolimus-Eluting BiOSS LIM C Dedicated Coronary Bifurcation Stent: Four-Year Results

This multicenter, randomized study aimed to compare the sirolimus-eluting BiOSS LIM C dedicated coronary bifurcation stent with second-generation -limus drug-eluting stents (rDESs) in the treatment of non-left main (non-LM) coronary bifurcation. The deployment of a single stent in the main vessel-main branch across a side branch was the default strategy in all patients. The primary endpoint was the rate of major cardiovascular events (cardiac death, myocardial infarction, and target lesion revascularization) at 48 months. We enrolled 230 patients, allocating 116 patients to the BiOSS LIM C group and 114 patients to the rDES group. Most procedures were elective (BiOSS vs. rDES: 48.3% vs. 59.6%, p = 0.09) and performed in bifurcations within the left anterior descending/diagonal branch (BiOSS vs. rDES: 51.7% vs. 61.4%, p = 0.15). At 48 months, there were no statistically significant differences between the BiOSS and rDES groups in terms of major adverse cardiovascular events (MACE), cardiac death, myocardial infarction (MI), or target lesion revascularization (TLR) as follows: MACEs-18.1% vs. 14.9%, HR 1.36, 95% CI 0.62-2.22, and p = 0.33; cardiac death-4.3% vs. 3.5%, HR 1.23, 95% CI 0.33-4.56, and p = 0.75; MI-2.6% vs. 3.5%, HR 0.73, 95% CI 0.17-3.23, and p = 0.68; and TLR-11.2% vs. 7.9%, HR 1.66, 95% CI 0.75-3.71, and p = 0.21. The implantation success rate of the BiOSS LIM C stent was very high, and the cumulative MACE rates were promising. The POLBOS 3 trial sets an important benchmark for treating non-LM coronary bifurcations (ClinicalTrials.gov NCT03548272).

Actuators for Implantable Devices: A Broad View

The choice of actuators dictates how an implantable biomedical device moves. Specifically, the concept of implantable robots consists of the three pillars: actuators, sensors, and powering. Robotic devices that require active motion are driven by a biocompatible actuator. Depending on the actuating mechanism, different types of actuators vary remarkably in strain/stress output, frequency, power consumption, and durability. Most reviews to date focus on specific type of actuating mechanism (electric, photonic, electrothermal, etc.) for biomedical applications. With a rapidly expanding library of novel actuators, however, the granular boundaries between subcategories turns the selection of actuators a laborious task, which can be particularly time-consuming to those unfamiliar with actuation. To offer a broad view, this study (1) showcases the recent advances in various types of actuating technologies that can be potentially implemented in vivo, (2) outlines technical advantages and the limitations of each type, and (3) provides use-specific suggestions on actuator choice for applications such as drug delivery, cardiovascular, and endoscopy implants.

6-year results of BiOSS stents in coronary bifurcation treatment

BACKGROUND

The wide variation in bifurcation anatomy has generated an ongoing search for stents explicitly designed for coronary bifurcations, and to date, results have been underachieved.

METHODS

The POLBOS I and POLBOS II were international, multicentre, randomized, open-label, controlled trials. Patients were randomly assigned to BiOSS Expert (in POLBOS I, biodegradable polymer eluting paclitaxel)/BiOSS LIM (in POLBOS II, biodegradable polymer eluting sirolimus) stent implantation or regular drug-eluting stent (rDES) deployment. A provisional T-stenting strategy was the default treatment option. The primary endpoint of this pooled data study was the cumulative rate of major adverse cardiovascular events (MACE) consisting of cardiac death, myocardial infarction (MI) and target lesion revascularization (TLR). Telephone follow-up was performed annually up to 72 months. (ClinicalTrials.gov Identifier: POLBOS I-NCT02192840, POLBOS II-NCT02198300).

RESULTS

The total study population consisted of 445 patients, 222 patients in the BiOSS group and 223 patients in the rDES group. The follow-up rate was 93.7% in the BiOSS group and 91.9% in the rDES group. At 72 months, there was no significant difference between BiOSS and rDES groups regarding MACE (25.7% vs 25.1%, HR 1.06, 95% CI 0.73-1.52), cardiac death (3.1% vs 4.0%, HR 0.94, 95% CI 0.43-2.34), MI (3.6% vs 4.9%, HR 0.76, 95% CI 0.32-2.89), TLR (18.9% vs 16.1%, HR 1.17, 95% CI 0.75-1.83) and stent thrombosis rates (0.9% vs 0.5%, HR 1.21, 95CI 0.75-2.09).

CONCLUSIONS

At the 6-year follow-up, clinically significant clinical events did not differ between BiOSS stents and rDES.

Non-Invasive Treatment for Coronary In-Stent Restenosis via Wireless Revascularization With Nitinol Active Stent

This paper reports a novel shape memory alloy (SMA) nitinol type active stent for non-invasive restenosis treatment, which operates using a radiofrequency (RF) electro-thermo-mechanical actuation technique for wireless revascularization. The developed stent is equipped with a capacitive pressure sensor for in-artery blood pressure measurement and can provide multiple expansion to restore the blood pressure flow. The device design, working principle, fabrication, and characterization of the nitinol active stent are reported in this work. The wireless monitoring feature is achieved via peak shifting in the reflection coefficient of the S₁₁ parameter. The active stent with initial diameter and resonant frequency of 2 mm and 315 MHz, respectively, is expanded uniformly in stages up to 4.2 mm in diameter when excited with an RF power of ∼30 W for 320 s. The active stent is delivered and deployed ex vivo inside the left coronary artery of a cervine heart. The stented cervine heart before and after wireless actuation is inspected via penetration of X-rays. Endoscopic images reveal the expansion of the stent strut profile within the lumen of the stented artery. The active stent expands in stages up to 3.7 mm in diameter to scaffold the cervine coronary artery after excited with an RF power of 46.7 W. The achievable wireless revascularization capability eradicates the necessity of reintervention and repeat stenting procedure, whereas real-time wireless monitoring provides rapid indication of in-artery re-narrowing occurrence.

The 2010s in clinical drug-eluting stent and bioresorbable scaffold research: a Dutch perspective

Dutch researchers were among the first to perform clinical studies in bare metal coronary stents, the use of which was initially limited by a high incidence of in-stent restenosis. This problem was greatly solved by the introduction of drug-eluting stents (DES). Nevertheless, enthusiasm about first-generation DES was subdued by discussions about a higher risk of very-late stent thrombosis and mortality, which stimulated the development, refinement, and rapid adoption of new DES with more biocompatible durable polymer coatings, biodegradable polymer coatings, or no coating at all. In terms of clinical DES research, the 2010s were characterised by numerous large-scale randomised trials in all-comers and patients with minimal exclusion criteria. Bioresorbable scaffolds (BRS) were developed and investigated. The Igaki-Tamai scaffold without drug elution was clinically tested in the Netherlands in 1999, followed by an everolimus-eluting BRS (Absorb) which showed favourable imaging and clinical results. Afterwards, multiple clinical trials comparing Absorb and its metallic counterpart were performed, revealing an increased rate of scaffold thrombosis during follow-up. Based on these studies, the commercialisation of the device was subsequently halted. Novel technologies are being developed to overcome shortcomings of first-generation BRS. In this narrative review, we look back on numerous devices and on the DES and BRS trials reported by Dutch researchers.

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.

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

Percutaneous coronary interventions are the primary revascularization strategy for the vast majority of patients with coronary artery disease. Nevertheless, challenging settings still limit optimal results, especially in case of significant tapering, bifurcations or primary angioplasty in ST-segment elevation myocardial infarction. Stentys^® Self-Apposing^® stent was designed to improve strut apposition to the vessel wall and to adapt to difficult targets. The Xposition S is a sirolimus-eluting stent with a novel delivery system, to improve accurate positioning. Several studies compared the device with traditional balloon-expandable stents, showing better results in terms of malapposition reduction and a noninferiority in relation to procedural outcomes. Available data show good clinical results, but a direct comparison with balloon-expandable stents from large randomized trials is still lacking. Thus, the Stentys Xposition S can be an alternative to traditional stents in dedicated scenarios, but strong evidence from large randomized trials is needed to derive stronger recommendations.