SUMMIT registry: one-year outcomes after implantation of the EPIC self-expanding nitinol stent in the femoropopliteal segment

Directional atherectomy and drug-coated balloon angioplasty vs. bare nitinol stent angioplasty for femoropopliteal artery lesions

Background: The present study evaluated the prognosis of directional atherectomy (DA)+drug-coated balloon (DCB) angioplasty for femoropopliteal artery lesions compared with bare nitinol stent (BNS). Patients and methods: This retrospective cohort study included patients with femoropopliteal artery lesions who underwent percutaneous endovascular surgery between January 2016 and June 2019. The primary outcome was the primary patency rate after 12, 24, and 36 months; the secondary outcomes comprised incidence of flow-limiting dissections, technical success, limb salvage, and all-cause death. Results: During the study period, 110 (44%) patients underwent DA+DCB, and 140 (56%) patients underwent bare nitinol stent (BNS). There were no differences in the 12- and 24-month patency rates of the two groups (98.2% vs. 93.6% and 68.2% vs. 60.0%, both p>.05). The 36-month primary patency rate in the DA+DCB group was significantly higher than that of the BNS group (27.3% vs. 15.7%, p=.003). The technical success rate and all-cause death were similar between groups (p>.05). Flow-limiting dissections occurred more frequently in the BNS group than in the DA+DCB group (27.9% vs. 10.9%, p=.033). After adjustment for potential confounders, such as sex, smoking, hypertension, hyperlipidemia, ABI after surgery, TASC II B, lesion length ≥15 cm, two-vessel runoff, and three-vessel runoff, the HR for primary patency rate comparing BNS to DA+DCB was 2.61 (95%CI: 1.61-4.25). Conclusions: In this retrospective cohort study, DA+DCB was associated with a higher 30-month primary patency rate and a lower flow-limiting dissection incidence than BNS.

Personalised nitinol stent for focal plaques: Design and evaluation

The purpose of this study is to develop personalised nitinol stents for arteries with one and two opposite focal plaques. Novel designs are evaluated through comparison with a commercial stent design, in terms of lumen gain and shape as well as stress levels in the media layer after stenting.

METHODS

Personalised stents are developed for arteries with one and two opposite focal plaques, based on medical imaging of patients and computer simulations. In silico analysis is then carried out for assessment of stent performance in the diseased arteries.

RESULTS

Personalised designs significantly increase the lumen gain, reduce the stresses in the media layer, and improve the lumen shape compared to the commercial nitinol stent.

CONCLUSION

The personalised designs show outstanding performance compared to the commercial stent.

SIGNIFICANCE

This pilot study proves that personalised nitinol stents are able to deliver desirable treatment outcomes.

Pioneering personalised design of femoropopliteal nitinol stents

BACKGROUND/MOTIVATION

Percutaneous femoropopliteal artery intervention moves towards personalised therapy, which requires design of unique lesion-specific stents. However, to date, not much progress has been made in the development of personalised stents.

OBJECTIVE

This paper aims to design personalised nitinol stents for femoropopliteal arteries based on medical imaging of patients and advanced computational mechanics, which is the first attempt to the authors' best knowledge.

METHODS

The design process is based on three objectives: (i) achieving the healthy lumen area; (ii) reducing the stress in the media layer; (iii) improving the lumen shape after stenting. The design parameters include the strut width and thickness, the crown length, the nominal radius and the number of strut units per crown. Using representative unit-cell models, the effects of the five geometric parameters on the stent performance are investigated thoroughly with numerical simulations. Then, design protocols, especially for the circumferentially varying strut size and the oval stent shape, are developed and fully evaluated for an asymmetric stenosis.

RESULTS

Using the design protocols, full personalised stents are designed for arteries with diffuse and focal plaques, based on medical imaging of patients. The personalised stent designs provide a double lumen gain, a reduced stress in the media layer and an improved lumen shape compared to a commercial stent.

CONCLUSIONS

The suggested protocols prove their high effectiveness in design of personalised stents, and the suggested approach can be applied to development of personalised therapies involving the use of stent technology including percutaneous coronary artery intervention, transcatheter aortic valve implantation, endovascular aneurysm repair and ureteric stenting.

Optimized drug-coated balloon angioplasty of the superficial femoral and proximal popliteal arteries using the Tack Endovascular System: TOBA III 12-month results

OBJECTIVE

The Tack Endovascular System (Intact Vascular, Wayne, Pa) combines low-metallic content with focal delivery to seal areas of dissection associated with balloon angioplasty. The device system is designed to treat vascular dissections in the superficial femoral and proximal popliteal arteries. Tack implants exert low radial force and are associated with minimal metal burden, which reduces the mechanical stress on the arterial wall in treating dissections after balloon angioplasty. This study investigated the safety and effectiveness of the Tack Endovascular System in patients with dissections after drug-coated balloon (DCB) angioplasty.

METHODS

The Tack Optimized Balloon Angioplasty III (TOBA III) study is a prospective, multicenter, single-arm study in which patients who underwent percutaneous transluminal angioplasty with the Medtronic IN.PACT Admiral DCB (Medtronic, Dublin, Ireland) and experienced dissection after angioplasty were treated with Tack implants. The primary end points were freedom from major adverse events at 30 days and primary patency at 12 months.

RESULTS

A total of 201 patients were enrolled in the trial, 169 with standard-length lesions (≥20 mm and ≤150 mm) and 32 with long-length lesions (>150 mm and ≤250 mm). Safety and effectiveness results were favorable compared with historical benchmarks at 12 months in the standard-lesion cohort. Notably, patients in the standard-lesion cohort experienced 95.0% primary patency, 97.5% freedom from clinically driven target lesion revascularization, 100% freedom from amputation, and 100% survival at 12 months (P < .0001). Primary patency in long-lesion patients was 89.3%, freedom from clinically driven target lesion revascularization was 96.8%, and freedom from amputation was 100% at 12 months. Device success was achieved in 95.8% (182/190) and 97.7% (43/44) of devices deployed into standard-lesion and long-lesion patients, respectively. Procedural success was 99.4% (168/169) and 100% (44/44) in the standard-lesion and long-lesion cohorts, respectively, with only one bailout stent placed in the entire population.

CONCLUSIONS

The Tack Endovascular System is a safe and effective treatment option for patients with dissections after angioplasty in the superficial femoral and proximal popliteal arteries, with high patency, low rates of secondary intervention, and low incidence of bailout stenting when it is used in combination with DCB.

Zilver PTX peripheral paclitaxel-eluting stent: a technology evaluation

INTRODUCTION

The Zilver PTX stent was the first self-expanding drug-coated stent approved by the United States Food and Drug Administration (US FDA) for use in the superficial femoral artery (SFA) above the knee. The main objective of this article is to review the design, safety, and efficacy of the Zilver PTX stent which was engineered to outperform bare metal stents (BMS) in this challenging environment.

AREAS COVERED

An evaluation of the Zilver PTX peripheral paclitaxel-coated stent design and a review of the current preclinical and clinical evidence regarding the use of this stent.

EXPERT OPINION

Stent implantation for the treatment of peripheral arterial disease (PAD) in the SFA was initially seen as a salvage option; however, stenting is now routinely offered as initial therapy for patients suffering from claudication and critical limb ischemia. The Zilver PTX stent has established efficacy and safety profiles for paclitaxel in the SFA; however, the development of biocompatible polymers capable of extending the elution time of anti-proliferative agents may lead to more effective stent platforms.

Endovascular treatment of atherosclerotic lesions in the superficial femoral artery and proximal popliteal artery using the sinus-SuperFlex-635 stent: twelve-month results from the HERO Registry

BACKGROUND

The aim of this study was to evaluate the safety and performance of the sinus-SuperFlex-635 self-expandable nitinol stent (Optimed GmbH) for the treatment of steno-occlusive lesions in the superficial femoral artery (SFA) and proximal popliteal artery (PPA).

METHODS

The prospective, multicenter, observational HERO study recruited 117 eligible patients (83 men; mean age 69.4±9.7y) from 7 centers in Belgium.

RESULTS

A total of 129 stents were successfully deployed in 121 lesions in 117 patients (100%). The patients presented with symptomatic ≥50% stenosis or chronic total occlusion (CTO) (30.6%). Mean lesion length was 71.4±56.3 mm. Moderate to severe calcification was present in 82.6% of the lesions. Acute lesion success (<30% residual stenosis) was achieved in 96.0%. There were no in-hospital serious adverse events. Duplex ultrasound-driven primary patency at 12 months was recorded in 84 of 107 (78.5%) lesions. The overall target lesion revascularization (TLR) rate was 8.4% at 12 months; the target extremity revascularization (TER) rate was 4.7%. Clinical assessment at 12 months demonstrated improvement by at least 1 Rutherford class, without the need for TLR (i.e. primary sustained clinical improvement) in 83.9% of patients and with the need for TLR in 90.6% of patients (i.e. secondary sustained clinical improvement).

CONCLUSIONS

Based on the high primary patency, low stent fracture rate and significant clinical improvement, combined with refined stent design and long stent availability, the sinus-SuperFlex-635 self-expandable nitinol stent proves its value in the treatment of complex femoropopliteal lesions.

Comparative Outcomes of Supera Interwoven Nitinol vs Bare Nitinol Stents for the Treatment of Femoropopliteal Disease: Insights From the XLPAD Registry

Purpose: To report a propensity score analysis comparing outcomes of the Supera interwoven nitinol stent to bare nitinol stents (BNS) in the femoropopliteal segment. Materials and Methods: A retrospective study was conducted utilizing data extracted from the Excellence in Peripheral Artery Disease (XLPAD) registry (ClinicalTrials.gov identifier NCT01904851) on 871 patients (mean age 65.1 years; 713 men) who underwent femoropopliteal balloon angioplasty with either Supera stent implantation in 118 limbs or other contemporary BNS in 753 limbs between January 2006 and December 2016. All patients in both groups were matched for baseline demographic and clinical characteristics in a 1:1 propensity score matching using the nearest neighbor method to create the 118-patient matched BNS cohort. One-year outcomes included all-cause mortality, target vessel revascularization (TVR), and target limb revascularization (TLR). An additional core laboratory analysis was conducted to measure the deployed length of Supera stents. Results: In unmatched data, the Supera stent group had a numerically lower rate of TVR (7.6% vs 13.4%, p=0.08) and a significantly lower 1-year TLR rate (7.6% vs 16.2%, p=0.02) compared to the BNS group. Both groups had similar 1-year mortality (2.5% vs 2.7%, p=0.9). Kaplan-Meier analysis demonstrated that the Supera group had a significantly lower risk of TVR (p=0.02) and TLR (p=0.002) than the BNS group. After propensity matching, the 1-year TVR estimate was lower for Supera stents (7.6% vs 12.7%, p=0.08) and significantly lower for TLR (7.6% vs 13.6%, p=0.04) than the BNS group. There was no statistically significant association between Supera stent elongation (>10% of the labeled stent length) and 1-year risk of TLR (p=0.6). Conclusion: Supera stent usage in femoropopliteal intervention was associated with reduced risk of 1-year repeat target limb revascularization compared with BNS treatment in both unmatched and matched cohorts.

Nitinol Stents in the Femoropopliteal Artery: A Mechanical Perspective on Material, Design, and Performance

Endovascular stenting has matured into a commonly used treatment for peripheral arterial disease (PAD) due to its minimally invasive nature and associated reductions in short-term morbidity and mortality. The mechanical properties of the superelastic Nitinol alloy have played a major role in the explosion of peripheral artery stenting, with modern stents demonstrating reasonable resilience and durability. Yet in the superficial femoral and popliteal arteries, even the newest generation Nitinol stents continue to demonstrate clinical outcomes that leave significant room for improvement. Restenosis and progression of native arterial disease often lead to recurrence of symptoms and reinterventions that increase morbidity and health care expenditures. One of the main factors thought to be associated with stent failure in the femoropopliteal artery (FPA) is the unique and highly dynamic mechanical environment of the lower limb. Clinical and experimental data demonstrate that the FPA undergoes significant deformations with limb flexion. It is hypothesized that the inability of many existing stent designs to conform to these deformations likely plays a role in reconstruction failure, as repetitive movements of the leg and thigh combine with mechanical mismatch between the artery and the stent and result in mechanical damage to both the artery and the stent. In this review we will identify challenges and provide a mechanical perspective of FPA stenting, and then discuss current research directions with promise to provide a better understanding of Nitinol, specific features of stent design, and improved characterization of the biomechanical environment of the FPA to facilitate development of better stents for patients with PAD.

Endovascular Interventions for Femoropopliteal Peripheral Artery Disease: A Network Meta-Analysis of Current Technologies

PURPOSE

To use network meta-analysis (NMA) to determine the optimal endovascular strategy for management of femoropopliteal peripheral artery disease (PAD) given the lack of multiple prospective randomized trials to guide treatment decisions.

MATERIALS AND METHODS

NMA is a new meta-analytic method that permits comparisons among any 2 therapies by combining results of a collection of clinical trials conducted in the same or similar patient population. NMA was used to analyze data from 15 randomized controlled trials (RCTs) and 10 prospective, multicenter, single-arm trials (combined evidence [CE] NMA) that evaluated target lesion revascularization (TLR) for 5 endovascular strategies: bare metal stent (BMS), polymer-covered metal stent (CMS), drug-eluting stent (DES), drug-coated balloon (DCB) and percutaneous transluminal angioplasty (PTA).

RESULTS

The RCT and CE NMAs included 2,912 (6,091) patients with 3,151 (6,786) person-years of follow-up. In the CE NMA, DCB provided a statistically significant 68% reduction in TLR compared with PTA and a statistically significant 53% reduction in TLR compared with BMS. BMS, CMS, and DES provided reductions in TLR of 33%, 48%, and 58% compared with PTA, with statistical significance achieved for CMS and DES. The significant reductions in TLR for DCB compared with PTA and BMS were replicated in the RCT NMA.

CONCLUSIONS

This NMA demonstrated that DCB provided better reduction in TLR rates compared with PTA and BMS.

Short vs prolonged dual antiplatelet treatment upon endovascular stenting of peripheral arteries

INTRODUCTION

Peripheral artery disease (PAD) is a highly prevalent disorder with a substantial economical burden. Dual antiplatelet treatment (DAPT) upon endovascular stenting to prevent acute thrombotic reocclusions is an universally accepted practice for postinterventional management of PAD patients. However, the optimal period of time for DAPT upon endovascular stenting is not known.

METHODS

In the current nonrandomized, retrospective monocentric study, we evaluated the duration of DAPT upon endovascular stenting. A total of 261 endovascular SFA and iliac stenting procedures were performed on 214 patients and these patients were subdivided into a short (4-6 weeks) or a prolonged (8-12 weeks) DAPT regime group. More than 65% of the patients included were male, approximately 35% were diabetic, and 61% had a history of smoking. Of all the patients, 90% exhibited a Rutherford stage 2-3, and approximately half of the patients had a moderate-to-severe calcified target lesion with a length of >13 cm. Major safety end points were defined as any bleeding, compartment syndrome, and ischemic events. In addition to this, patency, all-cause mortality, as well as amputation were followed up over a period of 12 months upon intervention.

RESULTS

Twelve months after endovascular stenting, primary patency in our cohort was comparable between the groups (83.94% short vs 79.8% long DAPT, P>0.05). Major bleeding occurred in 18 cases without any difference between the groups (P>0.05). In addition, during the 12-month follow-up, 6 (3.4%) patients in the short and 3 (3.5%) in the prolonged DAPT regime suffered a stroke/transient ischemic attack (P>0.05). In addition, there was no difference regarding mortality and amputation rate comparing short vs prolonged DAPT regime in a 12-month follow-up.

CONCLUSION

In the current cohort, prolonged DAPT after endovascular stenting had no beneficial effect on the outcome in a 12-month follow-up.

Design and Comparison of Large Vessel Stents: Balloon Expandable and Self-Expanding Peripheral Arterial Stents

Endovascular stenting has evolved over the last 50 years since its inception into the framework of management of vascular atherosclerotic disease. Stent design has evolved as lesion complexity has increased. Nevertheless, certain first principles regarding stent design have been recapitulated time and again with every iteration of endovascular stents. This article reviews principles of endovascular stent design and compares and contrasts key aspects of balloon expandable and self-expanding stents.

Diagnosis, classification, and treatment of femoropopliteal artery in-stent restenosis

In-stent restenosis is a pervasive challenge to the durability of stenting for the treatment of lower extremity ischemia. There is considerable controversy about the criteria for diagnosis, indications for treatment, and preferred algorithm for addressing in-stent restenosis. This evidence summary seeks to review existing information on strategies for the treatment of this difficult problem.

IN.PACT™ Admiral™ drug-coated balloon: Durable, consistent and safe treatment for femoropopliteal peripheral artery disease

Endovascular management of peripheral artery disease was until recently limited to percutaneous balloon angioplasty, atherectomy, stent grafts, and bare-metal stents. These therapies have been valuable, but plagued by high restenosis and revascularization rates. Important progress has been made with the introduction of combination devices, including drug-eluting stents and drug-coated balloons (DCB), designed to combat restenosis by locally delivering anti-proliferative drugs. In particular, promising clinical performance has been seen with the Medtronic IN.PACT™ Admiral™ DCB, with durable, consistent and safe results. Rigorous, randomized controlled trials have directly compared this and other drug-delivering devices to their non-drug-coated counterparts with data available through two years. Additionally, trials are ongoing to assess use of drug-coated technologies in combination with traditional therapies in hope of synergistic effects. This review gathers data from currently published clinical trials with the IN.PACT Admiral DCB for the treatment of femoropopliteal peripheral artery disease and explores the possible impact on continuing clinical practice.

Economic analysis of endovascular drug-eluting treatments for femoropopliteal artery disease in the UK

OBJECTIVES

To estimate the clinical and economic impact of drug-eluting endovascular treatment strategies for femoropopliteal artery disease compared with current standard of care.

DESIGN

Systematic literature search to pool target lesion revascularisations (TLR). Model-based per-patient cost impact and quasi-cost-effectiveness projection over 24 months based on pooled TLRs and current reimbursement.

SETTING

The UK's National Health Service (NHS).

PARTICIPANTS

Patients presenting with symptomatic femoropopliteal disease eligible for endovascular treatment.

INTERVENTIONS

Current National Institute for Health and Care Excellence (NICE) guideline-recommended treatment with percutaneous transluminal balloon angioplasty (PTA) and bailout bare metal stenting (BMS) versus primary BMS placement, or drug-coated balloon (DCB), or drug-eluting stent (DES) treatment.

PRIMARY AND SECONDARY OUTCOME MEASURES

24-month per-patient cost impact to NHS (primary outcome).

SECONDARY OUTCOMES

pooled 24-month TLR rates; numbers needed to treat (NNTs); cost per TLR avoided and estimated incremental cost-effectiveness ratio (ICER) in £ per quality-adjusted life year (QALY).

RESULTS

N=28 studies were identified, reporting on 5167 femoropopliteal lesions. Over 24 months, DCB, DES and BMS reduced TLRs of de novo lesions from 36.2% to 17.6%, 19.4% and 26.9%, respectively, at an increased cost of £43, £44 and £112. NNTs to avoid 1 TLR in 24 months were 5.4, 6.0 and 10.8, resulting in cost per TLR avoided of £231, £264 and £1204. DCB was estimated to add 0.011 QALYs, DES 0.010 QALYs and BMS 0.005 QALYs, resulting in estimated ICERs of £3983, £4534 and £20 719 per QALY gained. A subset analysis revealed more favourable clinical and economic outcomes for a 3.5 µg/mm(2) DCB with urea excipient, compared with the rest of DCBs. A modest reduction of 10% in DCB and DES prices made drug-eluting treatments dominant.

CONCLUSIONS

Widespread adoption of drug-eluting endovascular therapies for femoropopliteal disease would add meaningful clinical benefit at reasonable additional costs to the NHS. Based on currently available data, DCBs offer the highest clinical and economic value.

Supera self-expanding stents for endovascular treatment of femoropopliteal disease: a review of the clinical evidence

Femoropopliteal lesions account for a significant proportion of endovascular interventions for peripheral artery disease in patients with disabling claudication or chronic limb ischemia. The femoropopliteal artery crosses two joint structures (hip and knee joints) and courses through the muscular adductor canal in the thigh, which places the artery at increased biomechanical stress. There is a critical need for stent platforms with a reduced risk of stent fracture while maintaining patency during long-term follow-up. The Supera peripheral stent system has a braided nickel–titanium alloy stent designed to withstand the unique stressors along the course of the femoropopliteal artery. This design may be associated with improved patency in association with reduced stent fracture rates on short- and medium-term follow-up. Further studies, including randomized controlled studies, comparing the Supera interwoven nickel–titanium alloy stent system with other stent platforms and angioplasty alone are needed.