Radial access for peripheral vascular intervention: the S.M.A.R.T. RADIANZ Vascular Stent System

INTRODUCTION

Radial access is the standard of care for nearly all cardiac catheterization procedures. It improves patient satisfaction, reduces the length of stay, and is associated with fewer complications. However, few devices and tools are available for the treatment of peripheral arterial disease via a transradial approach (TRA). The S.M.A.R.T. RADIANZ Vascular Stent System is among the RADIANZ suite of products, which is aimed at expanding the portfolio of devices to treat peripheral arterial disease.

AREAS COVERED

In this Expert review, the following areas will be covered: (1) Current Landscape of peripheral vascular intervention (PVI) using TRA (2) Detailed description of the S.M.A.R.T. RADIANZ Vascular Stent System. (3) Ongoing clinical trials to evaluate safety of this approach. (4) Future directions and current regulatory status.

EXPERT OPINION

TRA for PVI is a promising approach. It holds the possibility of substantially improving the care of patients with peripheral arterial disease (PAD). Numerous challenges must be overcome to realize the full potential of a radial-to-peripheral (RTP) approach. The length of devices and the small sheath size are the main constraints of this approach. The results of the ongoing RADIANCY trial will demonstrate the safety, in selected patients, of the RADIANZ suite of products.

Stent fractures in the superficial femoral artery: predisposing factors and their implications

Abstract Background Fractures in stents implanted in the superficial femoral artery (SFA) are recognized complications of endovascular management of this arterial territory. Objectives The objective of this study was to determine the prevalence of fractures in stents implanted in the SFA and to identify predisposing factors for these fractures together with their impact on the patency of these devices. Methods The study included 39 patients (65.7±9.0 years) who previously underwent angioplasty for delivery of 56 stents into the SFA. During follow-up, which ranged from 7 to 46 months, variables were collected on the characteristics of the lesions treated and characteristics of the stents implanted. Two examiners independently analyzed digital radiographs for the presence of stent fractures and the patency of the devices. Results We found a 10.7% prevalence of fracture of implanted stents. Implantation of multiple stents was identified as a significant predisposing factor for fractures. We observed a marked tendency for fractures in female patients and in lesions treated with longer stents (> 150 mm). Stenosis exceeding 50% and occlusions were significantly more frequent in fractured stents. Conclusions This study suggests that implants longer than 150 mm and multiple stents are associated with higher device fracture rates. In cases with stent fractures, stenoses exceeding 50% and occlusions were significantly more frequent.

A case report of successful stent implantation through a fractured stent-strut in a superficial femoral artery based on bench testing simulation

BACKGROUND

Stent implantation through the stent-strut of a previously implanted self-expandable stent in the superficial femoral artery (SFA) is not usually performed because the additional stent cannot dilate sufficiently. The key point to achieve sufficient expansion of an additional stent is to break the stent-strut of the previously implanted stent. However, there is no report of how to break the stent-strut.

CASE SUMMARY

A 72-year-old man was admitted to our hospital with acute rest pain and coldness of his left leg; he was diagnosed with acute limb ischaemia. The angiogram demonstrated a fractured stent as well as stent occlusion in the left distal SFA. The guidewire could pass only through the stent-strut because of stent fracture. Fortunately, balloon angioplasty through the stent-strut and thrombolysis achieved successful revascularization. Thereafter, an additional stent was implanted in an attempt to manage the fractured and deformed stent. To obtain sufficient expansion of the additional stent, an experimental study to examine the balloon diameter and pressure to break the stent-strut was performed. Based on the results of the experiment, the stent-strut was successfully broken, and the additional stent was expanded through the stent-strut on the second intervention.

DISCUSSION

If an additional self-expandable stent is deployed through the stent-strut directly, it would not be sufficiently dilated. The key point in such a case is to break the stent-strut of the previously implanted stent by balloon inflation before deployment of the additional stent. The experimental study examined the balloon diameter and pressure that can break the stent-strut. This information would be useful when we implant an additional stent through a stent-strut.

One-Year Clinical Outcomes following Implantation of InnovaTM Self-Expanding Nitinol Stents in Patients with Peripheral Artery Diseases Presenting Femoropopliteal Artery Lesions

Aim: Although the Innova™ self-expanding nitinol stent (Boston Scientific, Marlborough, MA) exhibits acceptable performance in long-term safety and efficacy when used for the treatment of femoropopliteal (FP) lesions, clinical outcomes following its implantation have not been systematically studied in real-world settings. We investigated the one-year clinical outcomes after implantation of Innova™ self-expanding nitinol stents for the treatment of FP lesions in real-world settings.

Methods: In this multicenter study, 481 lesions in 453 consecutive patients with peripheral artery disease (PAD) (74 ± 9 years; male, 70%; diabetes mellitus, 61%; dialysis, 27%; critical limb ischemia, 37%) who underwent endovascular therapy with the implantation of Innova™ self-expanding nitinol stents for FP lesions were analyzed from February 2016 to April 2017. The primary endpoint was one-year restenosis, whereas the secondary endpoints included one-year major adverse limb events and predictors for one-year restenosis.

Results: The mean lesion length was 18 ± 10 cm. One-year restenosis and major adverse limb event rates were 36% and 18%, respectively. Multivariate analysis revealed that the presence of diabetes mellitus (odds ratio [OR]: 1.83; 95% confidence interval [CI]: 1.07–3.13), distal reference vessel diameter (OR: 1.86; 95% CI: 1.09–3.16), spot stenting (OR: 2.27; 95% CI: 1.27–4.06), and lack of one-year cilostazol treatment (OR: 0.58; 95% CI: 0.33–1.00) were independent risk factors for one-year restenosis.

Conclusion: The current study demonstrated one-year clinical outcomes after Innova™ self-expanding nitinol stent placement for the treatment of FP lesions, including challenging cases in real-world settings.

Drug-coated balloon versus uncoated percutaneous transluminal angioplasty for the treatment of atherosclerotic lesions in the superficial femoral and proximal popliteal artery: 2-year results of the MDT-2113 SFA Japan randomized trial

OBJECTIVES

To assess the longer-term safety and efficacy of the IN.PACT Admiral (MDT-2113) drug-coated balloon (DCB) for the treatment of de novo and non-stented restenotic lesions in the superficial femoral and/or proximal popliteal arteries versus uncoated percutaneous transluminal angioplasty (PTA) in a Japanese cohort.

BACKGROUND

Although DCBs are the newest endovascular strategy for patients with peripheral artery disease presenting with femoropopliteal lesions, there remains a paucity of results in non-Caucasian populations.

METHODS

IN.PACT SFA Japan is an independently-adjudicated, prospective, multicenter, randomized, single-blinded trial. Endpoints through 2 years included primary patency and a composite safety endpoint of freedom from device- and procedure-related death through 30 days, freedom from target limb major amputation and freedom from clinically-driven target vessel revascularization at 24 months.

RESULTS

One hundred patients were assigned by 2:1 randomization to treatment with the IN.PACT Admiral DCB (n = 68) or PTA (n = 32). The groups were well-matched at baseline. Mean lesion length for the DCB and PTA groups were 9.15 ± 5.85 and 8.89 ± 6.01 cm (P = 0.838), respectively. Patients treated with DCB exhibited superior 24-month primary patency compared to PTA (79.8% vs. 46.9%; log rank P < 0.001). The 24-month clinically driven target lesion revascularization rate was 9.1% for DCB versus 20.7% for PTA (P = 0.177). There were no device- or procedure-related deaths, major amputations, or thromboses in either group.

CONCLUSIONS

Two-year results from IN.PACT SFA Japan demonstrated persistently superior patency and low CD-TLR rates through 2 years when compared to uncoated PTA in Japanese patients. These data are consistent with other IN.PACT DCB trials.

A case complicated by floating fractured stent 141 months after nitinol stent implantation in the superficial femoral artery

An 80-year-old man received the implantation of a self-expanding stent (Luminexx, Bard, Inc., Murray Hill, NJ, USA) for an in-stent restenosis (ISR) lesion in the superficial femoral artery. However, angiography 141 months after the Luminexx stent implantation showed 90% ISR and a floating fractured stent in the Luminexx site. Furthermore, the floating fractured stent strut itself was completely separated and flowed toward the posterior tibial artery. The stent strut was removed by a catheter for removing intravascular foreign substances. <Learning objective: We report a case of a floating fractured stent 141 months after stent implantation in the superficial femoral artery (SFA). Although this case is rare, in endovascular therapy with stenting for SFA, it is necessary to consider the risk of stent fracture in the very late phase.>.

Impact of stent diameter on vascular response after self-expanding paclitaxel-eluting stent implantation in the superficial femoral artery

BACKGROUND

The optimal sizing of self-expanding paclitaxel-eluting stents (PES) in the treatment for superficial femoral artery (SFA) lesions is unclear. This study sought to investigate the influence of PES diameter on stent patency in SFA lesions using optical frequency domain imaging (OFDI).

METHODS

A total of 20 de novo SFA lesions were randomized 1:1 to receive either self-expanding PES with a nominal diameter of 6mm or 8mm. Follow-up angiography and OFDI was scheduled six months after stent implantation, and volumetric OFDI analysis was performed to evaluate vascular response to the stents. Volume index (VI) was defined as the volume divided by the stent length. The primary end point was lumen VI at the 6-month follow-up. Secondary end point was minimum lumen diameter (MLD) by quantitative vascular angiography (QVA) at the follow-up.

RESULTS

Stent length was 78.0±23.9mm in the 6-mm group and 70.0±23.6mm in the 8-mm group (p=0.46). Baseline QVA data were also similar between the two groups. MLD immediately after stent implantation was similar between the two groups (4.2±0.5mm in the 6-mm group and 3.9±0.5mm in the 8-mm group, p=NS). At the 6-month follow-up, MLD was greater in the 8-mm group compared to the 6-mm group (4.0±1.0mm vs. 3.2±0.4mm, p<0.05). Stent VI was larger in the 8-mm group (28.4±6.7mm³/mm vs. 22.2±1.2mm³/mm, p=0.01). Neointimal VI was similar between the two groups (5.8±2.9mm³/mm vs. 5.2±2.6mm³/mm, p=0.68). Lumen VI was greater in the 8-mm group (23.2±7.6mm³/mm vs. 17.3±2.6mm³/mm, p=0.04).

CONCLUSIONS

Chronic stent enlargement resulted in greater lumen area after implantation of self-expanding PES with a large diameter at the mid-term follow-up. Stent diameter might be important for stent patency in procedure with PES for SFA lesions.

Stent Fractures After Superficial Femoral Artery Stenting

Purpose: To determine the risk factors and clinical impact of stent fractures after superficial femoral artery (SFA) stenting. Methods: From May 2009 to June 2012, 171 consecutive patients (mean age 74.5±7.8, years; 106 men) who presented with SFA stenosis or occlusion in 205 limbs underwent stent implantation in the SFA at a single center. Stent fractures were determined by radiography and classified into types I through V. Loss of patency was assessed by duplex ultrasonography (>2.4 peak systolic velocity ratio) or angiography (percent diameter stenosis >50%). Results: The 12- and 24-month primary patency rates were 49.8% and 43.4%, respectively. Stent fractures occurred in 12.5% and 26.8% per limb (6.6% and 19.4% per stent) at 12 and 24 months, respectively. Primary patency was numerically worse in the stent fracture group but not statistically different from the group without fractures at 2 years. Primary patency for different classes of stent fracture were 30.8% (type I), 50.0% (type II), and 31.3% (type III–V). Hyperlipidemia (p=0.001), TransAtlantic Inter-Society Consensus II classification (p=0.007), chronic total occlusion (CTO; p<0.001), proximal lesion location (p=0.008), lesion calcification (p=0.025), total stent length (p=0.005), stent diameter (p=0.001), and number of stents (p=0.001) were statistically significant predictors of stent fracture. Multivariate analysis showed that CTO (hazard ratio 0.173, 95% confidence interval 0.042 to 0.716, p=0.015) was an independent predictor of stent fracture. Conclusion: Stent fractures occur more frequently in patients with CTOs after treatment of longer stented lesions. Although multivariate analysis showed that CTO was the only independent predictor regardless of stent length or number, the stent fracture rate was numerically higher in the severe calcification and proximal SFA lesion subgroups. Stent fracture did not appear to affect long-term patency rates, but this is yet to be confirmed with further follow-up.

Direct stent puncture technique for intraluminal stent recanalization in the superficial femoral and popliteal arteries in-stent occlusion: outcomes from a prospective clinical analysis of diabetics with critical limb ischemia

PURPOSE

To evaluate the efficacy and safety of "Direct Stent Puncture" technique for intraluminal stent recanalization in the femoro-popliteal segments.

METHODS AND MATERIALS

A cohort of diabetics who had symptomatic in-stent occlusion of the superficial femoral or popliteal arteries underwent endovascular recanalization. After antegrade failure, direct stent puncture technique was performed. The primary end-point was to efficacy assessment, intended as technical success and clinical improvement. The secondary end-point was safety assessment, intended as free of complication rate.

RESULTS

Fifty-four patients (37 men; 73.6±8.5 years) underwent direct stent puncture technique, after several unsuccessful antegrade attempts to cross the occluded stent. Technical success for intraluminal stent recanalization was achieved in 53/54 (98.2%) of cases and failed in 1/54 (1.8%). Clinical improvement was obtained in 51/54 (94.4%) of cases, with regression of the clinical symptoms and improvement of the TcPO2, from 3±18 mmHg to 43±11 mmHg after 15 days (p<0.001). Free of complications rate was 92.5%. In 2/54 (3.7%) of cases distal embolization occurred, in 1/54 (1.9%) case a sudden vessel thrombosis was diagnosed after 12 hours and in 1/54 (1.9%) case hematoma at the stent puncture site was observed.

CONCLUSIONS

Direct Stent Puncture technique is an efficacy and safety option for intraluminal stent recanalization in the femoro-popliteal segment in-stent occlusion.

Pilot trial of cryoplasty or conventional balloon post-dilation of nitinol stents for revascularization of peripheral arterial segments: the COBRA trial

OBJECTIVES

The purpose of this study is to compare post-dilation strategies of nitinol self-expanding stents implanted in the superficial femoral artery of diabetic patients with peripheral arterial disease.

BACKGROUND

Endovascular treatment of superficial femoral artery disease with nitinol self-expanding stents is associated with high rates of in-stent restenosis in patients with diabetes mellitus.

METHODS

We conducted a prospective, multicenter, randomized, controlled clinical trial of diabetic patients to investigate whether post-dilation of superficial femoral artery nitinol self-expanding stents using a cryoplasty balloon reduces restenosis compared to a conventional balloon. Inclusion criteria included diabetes mellitus, symptomatic peripheral arterial disease, and superficial femoral artery lesions requiring implantation of stents>5 mm in diameter and >60 mm in length. Primary endpoint was binary restenosis at 12 months, defined as ≥2.5-fold increase in peak systolic velocity by duplex ultrasonography.

RESULTS

Seventy-four patients, with 90 stented superficial femoral artery lesions, were randomly assigned to post-dilation using cryoplasty (n=45 lesions) or conventional balloons (n=45 lesions). Mean lesion length was 148±98 mm, mean stented length was 190±116 mm, mean stent diameter was 6.1±0.4 mm, and 50% of the lesions were total occlusions. Post-dilation balloon diameters were 5.23±0.51 mm versus 5.51±0.72 mm in the cryoplasty and conventional balloon angioplasty groups, respectively (p=0.02). At 12 months, binary restenosis was significantly lower in the cryoplasty group (29.3% vs. 55.8%, p=0.01; odds ratio: 0.36, 95% confidence interval: 0.15 to 0.89).

CONCLUSIONS

Among diabetic patients undergoing implantation of nitinol self-expanding stents in the superficial femoral artery, post-dilation with cryoplasty balloon reduced binary restenosis compared to conventional balloon angioplasty. (Study Comparing Two Methods of Expanding Stents Placed in Legs of Diabetics With Peripheral Vascular Disease [COBRA]; NCT00827853).