Long-term results of ePTFE stent-graft versus angioplasty in the femoropopliteal artery: single center experience from a prospective, randomized trial

Exploring the Reporting Standards of Randomised Controlled Trials Involving Endovascular Interventions for Peripheral Arterial Disease: A Systematic Review

OBJECTIVE

Endovascular technology innovation requires rigorous evaluation in high quality randomised controlled trials (RCTs). However, due to numerous methodological challenges, RCTs evaluating endovascular interventions are complex and potentially difficult to design, conduct, and report. This systematic review aimed to assess the quality of reporting of RCTs for endovascular interventions for lower limb peripheral arterial disease (PAD).

DATA SOURCES AND REVIEW METHODS

A systematic review of Medline, Embase, and the Cochrane Library databases from inception to December 2021 was performed to identify RCTs including participants with PAD undergoing any infrainguinal lower limb endovascular intervention. Study data were extracted and assessed against the Consolidating Standards of Reporting Trials extension for Non-Pharmacological Treatments (CONSORT-NPT) and the Template for Intervention Description and Replication (TIDieR) checklists. Descriptive statistics were used to summarise general study details and reporting standards of the trials.

RESULTS

After screening 6 567 abstracts and 526 full text articles, 112 eligible studies were identified, reporting on 228 different endovascular devices and techniques. Details judged sufficient to replicate the investigated intervention were provided for 47 (21%) interventions. It was unclear whether the description was reported with sufficient details in a further 56 (24%), and the description was judged inadequate in 125 (55%). Any intervention descriptions were provided for 184 (81%), with variable levels of detail (some in 134 [59%] and precise in 50 [22%]). Standardisation of intervention or some aspect of this was reported in 25 (22%) trials, but only one specified that adherence to the study protocol would be monitored.

CONCLUSION

The quality of the reporting standards of RCTs investigating lower limb endovascular treatments is severely limited because the interventions are poorly described, standardised, and reported. PROSPERO registration number: CRD42022288214.

Prospective, randomized, multicenter clinical study comparing a self-expanding covered stent to percutaneous transluminal angioplasty for treatment of upper extremity hemodialysis arteriovenous fistula stenosis

Use of a covered stent after percutaneous transluminal angioplasty (PTA) was compared to PTA alone for treatment of upper extremity hemodialysis patients with arteriovenous fistula (AVF) stenoses. Patients with AVF stenosis of 50% or more and evidence of AVF dysfunction underwent treatment with PTA followed by randomization of 142 patients to include a covered stent or 138 patients with PTA alone. Primary outcomes were 30-day safety, powered for noninferiority, and six-month target lesion primary patency (TLPP), powered to test whether TLPP after covered-stent placement was superior to PTA alone. Twelve-month TLPP and six-month access circuit primary patency (ACPP) were also hypothesis tested while additional clinical outcomes were observed through two years. Safety was significantly non-inferior while six- and 12-month TLPP were each superior for the covered stent group compared to PTA alone (six months: 78.7% versus 55.8%; 12 months: 47.9% versus 21.2%, respectively). ACPP was not statistically different between groups at six-months. Observed differences at 24 months favored the covered-stent group: 28.4% better TLPP, fewer target-lesion reinterventions (1.6 ± 1.6 versus 2.8 ± 2.0), and a longer mean time between target-lesion reinterventions (380.4 ± 249.5 versus 217.6 ± 158.4 days). Thus, our multicenter, prospective, randomized study of a covered stent used to treat AVF stenosis demonstrated noninferior safety with better TLPP and fewer target-lesion reinterventions than PTA alone through 24 months.

Network Analysis of Endovascular Treatment Strategies for Femoropopliteal Arterial Occlusive Disease

PURPOSE

Endovascular treatment of femoropopliteal arterial diseases remains controversial. We conducted a Bayesian network meta-analysis of randomized controlled trials aiming to investigate the efficacy differences between paclitaxel- or sirolimus-eluting stents, covered stents, drug-coated balloons, bare metal stents, and percutaneous transluminal angioplasty.

METHOD

MEDLINE, Embase, Ovid, and other relevant online material were searched up to October 21, 2020. Primary endpoints were primary patency and target lesion revascularization at 6, 12, and more than 24 months.

RESULTS

Thirty-eight eligible trials included 6026 patients. In terms of primary patency, drug eluting stents were ranked as the most effective treatment based on the surface under the cumulative ranking curve values at 6 (80.6), 12 (78.4), and more than 24 months (96.5) of follow-ups. In terms of target lesion revascularization, drug eluting stents were ranked as the most effective treatment based on the surface under the cumulative ranking curve values at 6 (90.3), 12 (71.3), and more than 24 months (82.1) of follow-ups. Covered stents and bare metal stents had higher ranks in target lesion revascularization than those in primary patency. Sirolimus stents had a higher rank than paclitaxel stents.

CONCLUSION

Drug eluting stents showed encouraging results in primary patency rates and freedom from target lesion revascularization at all phases of follow-up for femoropopliteal arterial diseases. Sirolimus stents appear to be more effective in femoropopliteal segment than paclitaxel stent.

A computational study of fatigue resistance of nitinol stents subjected to walk-induced femoropopliteal artery motion

Fatigue resistance of nitinol stents implanted in femoropopliteal arteries is a critical issue because of their harsh biomechanical environment. Limb flexions due to daily walk expose the femoropopliteal arteries and, subsequently, the implanted stents to large cyclic deformations, which may lead to fatigue failure of the smart self-expandable stents. For the first time, this paper utilised the up-to-date measurements of walk-induced motion of a human femoropopliteal artery to investigate the fatigue behaviour of nitinol stent after implantation. The study was carried out by modelling the processes of angioplasty, stent crimping, self-expansion and deformation under diastolic-systolic blood pressure, repetitive bending, torsion and axial compression as well as their combination. The highest risk of fatigue failure of the nitinol stent occurs under a combined loading condition, with the bending contributing the most, followed by compression and torsion. The pulsatile blood pressure alone hardly causes any fatigue failure of the stent. The work is significant for understanding and improving the fatigue performance of nitinol stents through innovative design and procedural optimisation.

Comparative Effectiveness of Endovascular Treatment Modalities for De Novo Femoropopliteal Lesions: A Network Meta-analysis of Randomized Controlled Trials

Purpose: To report the results of a network meta-analysis of randomized controlled trials (RCTs) comparing multiple endovascular treatments for de novo femoropopliteal lesions. Materials and Methods: The MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases were systematically searched on June 1, 2019, for prospective RCTs comparing 14 treatments [ie, atherectomy, brachytherapy, cryoplasty, cutting balloons, drug-coated balloons, bare nitinol stents, drug-eluting stents (DES), covered stents (CS), and combinations] in the treatment of de novo femoropopliteal lesions. Outcomes were technical success; binary restenosis and target lesion revascularization (TLR) at 6, 12, and/or 24 months; and all-cause mortality at 12 months. Ultimately, 53 articles reporting on 45 studies (91 study arms; 5565 patients) were selected. For the technical success outcome, all types of stents, all balloons, and all atherectomy devices were aggregated in stent, balloon, and atherectomy technology groups, respectively. Results: In terms of technical success for aggregated treatment types, stent technology was the most effective treatment and was better than balloon and atherectomy technologies. In terms of binary restenosis, DES was the most effective single treatment at the 6- and 12-month follow-up and CS at the 24-month follow-up. Both DES and CS were better than the majority of other single treatments, including balloon angioplasty, cutting balloon, cryoplasty, directional atherectomy, and bare nitinol stent during all follow-up periods. In terms of TLR, DES was the second most effective single treatment and the most effective single treatment at the 6- and 12-month follow-up intervals; CS was the most effective single treatment at the 24-month follow-up. Both DES and CS were better than the majority of other single treatments. The 12-month all-cause mortality of both DES and CS were similar to other treatments, whereas cryoplasty seemed to be the least effective treatment with regard to binary restenosis and TLR. Conclusion: Both DES and CS had substantial advantages in terms of restenosis and TLR in femoropopliteal lesions and were similar to aggregate stent technology in terms of technical success. DES performed better within 12 months after operation and CS at ~24 months, but neither had much advantage in terms of mortality. In contrast, cryoplasty seemed to be a less effective treatment.

Comparative Efficacy and Safety of Endovascular Treatment Modalities for Femoropopliteal Artery Lesions: A Network Meta-analysis of Randomized Controlled Trials

PURPOSE

We conducted a network meta-analysis of randomized controlled trials comparing the efficacy and safety of multiple endovascular treatments for femoropopliteal lesions.

METHODS

Nine treatments for femoropopliteal lesions were identified. We compared major amputation and all-cause mortality at 12-month follow-ups and primary patency at 6-, 12- and 24-month follow-ups of the treatments.

RESULTS

Altogether, 26 studies (52 study arms; 4102 patients) were considered eligible. In terms of primary patency, drug-eluting stent (DES) placement was the most effective treatment at 6- and 12-month follow-ups and covered stent (CS) placement at 24-month follow-ups, whereas directional atherectomy (DA) was the least effective treatment during all follow-up periods; both DES and CS placements were better than the majority of other single treatments, including balloon angioplasty, DA, nitinol stent (NS) placement and drug-coated balloon use, during all follow-up periods. In terms of 12-month major amputation and all-cause mortality, DA was the most safe treatment, whereas NS placement was the least safe single treatment.

CONCLUSIONS

DES and CS placements have shown encouraging results in terms of primary patency for femoropopliteal lesions, DES placement performs better within 12 months after operation and CS placement at approximately 24 months, while DA seems to be less effective. DA may be better than other treatments in terms of major amputation and all-cause mortality, while NS seems to be less safe.

Preoperative CT-scan-based sizing and in-stent restenosis in peripheral endovascular revascularizations

Objectives This study evaluates the effect of stent sizing with CT-scan on the incidence of restenosis in peripheral arterial disease. Methods This retrospective study included 59 patients with 66 arterial lesions who underwent a endovascular procedure for peripheral arterial disease between April 2013 and October 2013. All patients had de novo iliac or femoral lesions, were candidates for an endovascular procedure alone and underwent CTA preoperatively. The stent actually implanted, whose dimensions were chosen on the basis of the operator's experience on an intraoperative 2D angiography, was compared to the "ideal" stent chosen retrospectively on the basis of precise lesion sizing by the preoperative CTA. Planning was considered "discordant" if there was a difference in length of more than 20 mm and/or a difference in diameter of more than 1 mm between the ideal stent and the actual stent. Results For iliac lesions, discordance essentially concerned stent diameter (36.1%), whereas stent length was the main reason for discordance for femoral lesions (36.7%). The median length of follow-up was 18 months (range 6-24). For iliac lesions, freedom from restenosis at 24 months was higher for patients with concordant planning (90% vs. 62.5%, p = 0.045). Most restenoses occurred in the external iliac artery, where there was a tendency towards oversizing of the implanted stent. For femoral lesions, the restenosis-free rate at 24 months was higher for patients with concordant planning (77.8% vs. 50%, p = 0.057). A multivariate analysis was conducted on the prediction of restenosis. Among factors, only discordant planning was found to be a significant predictor of restenosis with an odds ratio of 0.115 (95% confidence interval, 0.02-0.674; p = 0.016). Conclusion The absence of sizing for peripheral lesions engenders a tendency to choose the wrong stent, in particular in terms of diameter in iliac arteries and length in femoral arteries.

Predictors of Failure of Endovascular Therapy for Peripheral Arterial Disease

The objective of this study was to assess the usefulness of a comparison of clinical failure and restenosis rates of endovascular procedures at 1 year in patients with peripheral arterial disease. The resulting comparison is presented as “clinical failure/restenosis coordinate.” The authors screened 171 papers describing the outcome of lower extremity angioplasty or stent placement. In 20 of them, authors reported detailed outcomes of interest, including baseline demographic measurements, location of arterial occlusive lesions, a measure of restenosis (measured by ankle-brachial indices, ultrasonography, or angiography), and clinical outcomes (mortality, repeat percutaneous transluminal angioplasty, or amputation). An overview of these 20 angioplasty papers was performed. Besides the usual meta-analyses of each end point separately, data were also plotted as coordinates of clinical failure versus restenosis. The clinical failure-to-restenosis coordinate was calculated and reported for percutaneous transluminal angioplasty of the aortoiliac and femoropopliteal distributions. Clinically reported outcomes in the literature were used to calculate the clinical failure/restenosis coordinate. This value was significantly different for various locations of the angioplasty and various baseline angiographic characteristics. A numeric coordinate pair of clinical failure and restenosis is identifiable in patients undergoing endovascular treatment of peripheral arterial disease. The varying coordinates may be important in elucidating the incidence and mechanisms of clinical failure after endovascular treatment. The coordinate reported in this article is hypothesis-generating about mechanisms of endovascular treatment failure. This coordinate is important in determining the role of restenosis in the clinical failure of endovascular therapy of peripheral arterial disease.

Contemporary Endovascular Treatment for Disease of the Superficial Femoral and Popliteal Arteries: An Integrated Device-Based Strategy

Endovascular therapy for disease of the superficial femoral artery (SFA) and the popliteal artery remains controversial. Percutaneous treatment of this arterial segment presents a particular technical challenge, as the extent of disease varies from short, focal, and stenotic to long, diffuse, and occluded lesions. Over the last 2 decades, multiple therapies have been evaluated, including simple balloon angioplasty, directional atherectomy, stenting (both balloon-expandable and self-expanding), and more recently, intra-arterial radiation, laser, and cryotherapy. Regardless of which modality is used, however, endovascular therapy as a revascularization strategy has the potential to improve symptoms and quality of life and, in selected patients, to avoid limb amputation. While percutaneous endovascular treatment has been historically associated with high procedural success and favorable short and intermediate-term patency rates, long-term clinical results have proven disappointing. Conventional balloon angioplasty is limited by elastic recoil, dissection, and restenosis. Balloon-expandable stents (particularly in the distal SFA) are associated with late stent deformation and mechanical compression, with resultant late clinical failure. Newer self-expanding stents have shown improved initial results but have been limited by late mechanical fatigue and associated restenosis. With the development of several newer endovascular techniques in recent years, the possibilities for treating this condition have increased dramatically. Currently, no long-term comparative data exist regarding the role of these alternative technologies. This article summarizes and compares important data about new endovascular options for intervention therapy in SFA and popliteal disease. In addition, based on this analysis, we propose a contemporary treatment strategy, integrating older and newer technologies into a real-world algorithm.

Comparison of the Results of Percutaneous Transluminal Angioplasty and Stenting with Medical Treatment for Claudicants Who Have Superficial Femoral Artery Occlusive Disease

The outcomes of medical management of peripheral vascular disease localized to the superficial femoral artery (SFA) were compared with those obtained by percutaneous transluminal angioplasty (PTA) with or without stenting in a review of selected studies.

The natural history of localized SFA disease is favorable, with major amputation rates less than 10% and revascularization in only 18% of patients over a 10-year interval.

Conservative treatment of claudicants shows increases (150%) in walking distance if the ankle brachial index (ABI) is over 0.6 and patients stop smoking. Analysis of 10 trials (882 patients) of PTA with or without stenting found that the overall primary patency rates at 12 months were 71.1% for PTA plus stenting and 58.3% for PTA alone. Technical success with PTA with or without stenting is over 90%, and early results at 6 months are superior to those with exercise. In three randomized controlled trials, however, the difference between PTA and medical treatment at 2 years, whether measured by walking distance or ABI, was not significant, nor was the quality of life. For long-term improvement in walking distance (> 1 year) in the claudicant, intervention is not superior to medical treatment and a monitored exercise program. Consideration should be given to including a nonintervention control group and 2-year outcomes in the evaluation of new SFA stents.

Effectiveness of Viabahn in the Treatment of Superficial Femoral Artery Occlusive Disease

Purpose: To evaluate the effectiveness of the Viabahn stent-graft in the treatment of superficial femoral artery (SFA) occlusive disease. Methods: A systematic review and meta-analysis of published studies was performed to evaluate the efficacy of the Viabahn for SFA lesions. Studies were stratified according to controlled vs uncontrolled design and analyzed using random-effects models. Outcomes are reported as the risk ratio (RR) and 95% confidence interval (CI). Four prospective randomized controlled trials, one retrospective controlled study, and 9 uncontrolled studies were identified. Results: In controlled studies, primary patency with the Viabahn was superior to other interventions at 1 year (RR 0.63, 95% CI 0.49 to 0.82, p<0.001) and ankle-brachial index (ABI) improvement was greater at 6 months (mean difference 0.05, 95% CI 0.01 to 0.09, p=0.01) compared with other interventions. Subgroup analysis demonstrated a lower incidence of stent fracture in lesions with >15-cm stented lengths. In uncontrolled studies, ABI improvement was consistently superior at all measurement points during follow-up. Conclusions: Current evidence suggests that the Viabahn stent-graft is a safe and effective option for symptomatic SFA lesions. Prospective multicenter randomized controlled trials with long-term follow-up are needed to confirm the sustained efficacy of the Viabahn device.

Angioplasty versus bare metal stenting for superficial femoral artery lesions

BACKGROUND

Lower limb peripheral arterial disease (PAD) is a common, important manifestation of systemic atherosclerosis. Stenoses or occlusions in the superficial femoral artery may result in intermittent claudication or even critical ischaemia, which may be treated by balloon angioplasty with or without stenting. This is the first update of a review published in 2009.

OBJECTIVES

The primary aim was to determine the effect of percutaneous transluminal angioplasty (PTA) compared with PTA with bare metal stenting for superficial femoral artery (SFA) stenoses on vessel patency in people with symptomatic (Rutherford categories1 to 6; Fontaine stages II to IV) lower limb peripheral vascular disease.In addition, we assessed the efficacy of PTA and stenting in improving quality of life, ankle brachial index and treadmill walking distance.

SEARCH METHODS

For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched August 2013) and the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 6).

SELECTION CRITERIA

Randomised trials of angioplasty alone versus angioplasty with bare metal stenting for the treatment of superficial femoral artery stenoses.

DATA COLLECTION AND ANALYSIS

Two review authors (MC, CT) independently selected suitable trials, assessed trial quality and extracted data. Furthermore, these two review authors performed assessments of methodological quality and wrote the final manuscript. The third review author (ADM) cross-checked all stages of the review process.

MAIN RESULTS

We include three new studies in this update, making a total of 11 included trials with 1387 participants. The average age was 69 years and all trials included men and women. Participants were followed for up to two years. There was an improvement in primary duplex patency at six and 12 months in participants treated with PTA plus stent over lesions treated with PTA alone (six months: odds ratio (OR) 2.90, 95% confidence interval (CI) 1.17 to 7.18, P = 0.02, six studies, 578 participants; 12 months: OR 1.78, 95% CI 1.02 to 3.10, P = 0.04, nine studies, 858 participants). This was lost by 24 months (P = 0.06). There was a significant angiographic patency benefit at six months (OR 2.49, 95% CI 1.49 to 4.17, P = 0.0005, four studies, 329 participants) which was lost by 12 months (OR 1.30, 95% CI 0.84 to 2.00, P = 0.24, five studies, 384 participants). Ankle brachial index (ABI) and treadmill walking distance showed no improvement at 12 months (P = 0.49 and P = 0.57 respectively) between participants treated with PTA alone or PTA with stent insertion. Three trials (660 participants) reported quality of life, which showed no significant difference between participants treated with PTA alone or PTA with stent insertion at any time interval. Antiplatelet therapy protocols and inclusion criteria regarding affected arteries between trials showed marked heterogeneity.

AUTHORS' CONCLUSIONS

Although there was a short-term gain in primary patency there was no sustained benefit from primary stenting of lesions of the superficial femoral artery in addition to angioplasty. Future trials should focus on quality of life for claudication and limb salvage for critical ischaemia.

Systematic review and meta-analysis of additional technologies to enhance angioplasty for infrainguinal peripheral arterial occlusive disease

Background

There are several additional techniques designed to enhance conventional percutaneous transluminal balloon angioplasty (PTA). This systematic review assessed current evidence on the clinical effectiveness of additional techniques for infrainguinal peripheral arterial occlusive disease (PAD).

Methods

Relevant electronic databases, including MEDLINE, were searched in May 2011. The population comprised participants with symptomatic PAD undergoing endovascular treatment for disease distal to the inguinal ligament. Interventions were additional techniques compared with conventional PTA. Main outcome measures were restenosis and need for reintervention. Randomized clinical trials (RCTs) of clinical effectiveness were assessed for quality and data were extracted. Where appropriate, meta-analysis was undertaken to produce risk ratios (RRs).

Results

Forty RCTs were selected. Meta-analysis showed a significant benefit in reducing restenosis rates at 6 months for self-expanding stents (RR 0·49) and drug-coated balloons (RR 0·40), and at 12 months for endovascular brachytherapy (RR 0·63). There was also evidence that use of a stent-graft significantly reduced restenosis compared with PTA, as did drug-eluting stents compared with bare-metal stents. Meta-analysis showed that use of drug-coated balloons was associated with significantly lower reintervention rates than PTA alone at 6 months (RR 0·24) and 24 months (RR 0·27) of follow-up. There was also evidence of significantly lower reintervention rates for self-expanding stents at 6 months. Other techniques did not show significant treatment effects for restenosis or reintervention.

Conclusion

The conclusions of this review should be tempered by small sample sizes, lack of clinical outcome measures and differing outcome definitions, making direct comparison across trials difficult. However, self-expanding stents, drug-eluting stents and drug-coated balloons appeared to be the most promising technologies worthy of future study.

Innovative use of self-expanded polytetrafluoroethylene endoprosthesis for percutaneous endovascular interventions

VIABAHN® endoprosthesis (Gore & Associates, Flagstaff, AZ), a nitinol self-expanding polytetrafluoroethylene (PTFE) lined stent, has demonstrated utility for percutaneous treatment of chronic occlusive disease involving the superficial femoral artery. In a case series communication we aimed to describe the feasibility of a PTFE-lined stent for percutaneous treatment of conditions other than chronic occlusive disease. We report the successful use of PTFE-endoprosthesis to percutaneously treat several vascular conditions, including arterio-venous fistula closure, reconstruction of a distal limb of an aorto-femoral endoprosthesis aneurysm, femoral artery perforation repair, and an exclusion of large saphenous vein graft aorto-coronary bypass aneurysm. This case series illustrates the feasibility of the "off-label" use of self-expanded PTFE endoprosthesis to percutaneously treat several conditions, which would otherwise require "open" surgical reconstructions.

The BioStent: novel concept for a viable stent structure

OBJECTIVES

Percutaneous stenting of occluded peripheral vessels is a well-established technique in clinical practice. Unfortunately, the patency rates of small-caliber vessels after stenting remain unsatisfactory. The aim of the BioStent concept is to overcome in-stent restenosis by excluding the diseased vessel segment entirely from the blood stream, in addition to providing an intact endothelial cell layer.

DESIGN

The concept combines the principles of vascular tissue engineering with a self-expanding stent: casting of the stent within a cellularized fibrin gel structure, followed by bioreactor conditioning, allows complete integration of the stent within engineered tissue.

MATERIALS AND METHODS

Small-caliber BioStents (Ø=6 mm; n=4) were produced by casting a nitinol stent within a thin fibrin/vascular smooth muscle cell (vSMC) mixture, followed by luminal endothelial cell seeding, and conditioning of the BioStent within a bioreactor system. The potential remodeling of the fibrin component into tissue was analyzed using routine histological methods. Scanning electron microscopy was used to assess the luminal endothelial cell coverage following the conditioning phase and crimping of the stent.

RESULTS

The BioStent was shown to be noncytotoxic, with no significant effect on cell proliferation. Gross and microscopic analysis revealed complete integration of the nitinol component within a viable tissue structure. Hematoxylin and eosin staining revealed a homogenous distribution of vSMCs throughout the thickness of the BioStent, while a smooth, confluent luminal endothelial cell lining was evident and not significantly affected by the crimping/release process.

CONCLUSIONS

The BioStent concept is a platform technology offering a novel opportunity to generate a viable, self-expanding stent structure with a functional endothelial cell lining. This platform technology can be transferred to different applications depending on the luminal cell lining required.

Plaque Excision in Management of Lower Extremity Peripheral Arterial Disease with the SilverHawk Atherectomy Catheter

Atherectomy, the removal of plaque from diseased vessels, is theoretically appealing with respect to various procedures used for revascularization of lower extremity vessels. Instead of damaging the native vessel by pushing aside plaque with a balloon or stent, the plaque is removed. Many atherectomy devices have been designed in attempts to achieve this goal. The SilverHawk device is the latest percutaneous device employing this treatment strategy. We discuss patient selection, technical considerations, and strategies for both above and below the knee revascularization, as well as pitfalls in each location based on our experience with over 200 patients.

Current approach to the diagnosis and treatment of femoral-popliteal arterial disease. A systematic review

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis affecting 5 million adults in the United States, with an age-adjusted prevalence of 4% to 15% and increasing up to 30% with age and the presence of cardiovascular risk factors. In this article we focus on lower extremity PAD and specifically on the superficial femoral and proximal popliteal artery (SFPA), which are the most common anatomic locations of lower extremity atherosclerosis. We summarize current evidence and perform a systematic review on the diagnostic evaluation as well as the medical, endovascular and surgical management of SFPA disease.

Results With Viabahn-Assisted Subintimal Recanalization for TASC C and TASC D Superficial Femoral Artery Occlusive Disease

Objectives: Many investigators including TransAtlantic Inter-Society Consensus (TASC) recommend against primary endovascular treatment for severe (TASC C and D) superficial femoral artery (SFA) disease. Vein bypass is preferable but may not be appropriate due to comorbidities or lack of suitable vein. This study reviews our results with Viabahn stent graft-assisted subintimal recanalization (VASIR) for TASC C and D SFA atherosclerosis. Methods: In all, 13 males and 14 females, mean age 72 ± 11 years underwent 28 VASIR for severe (TASC C 8 of 28, TASC D 20 of 28, and 5 of 28 no continuous infrapopliteal runoff artery) SFA disease. Indications were claudication (14 of 28 limbs), ischemic rest pain (6 of 28), and tissue loss (8 of 28). Viabahn stent graft-assisted subintimal recanalization was chosen instead of bypass due to comorbidities or lack of vein. Patients received aspirin and, if not already taking warfarin, they also received clopidogrel. Patients were examined with Ankle-brachial Index (ABI) and duplex scan at 1 month, then every 3 months after VASIR. Results Viabahn stent graft-assisted subintimal recanalization was technically successful in all. Ankle-brachial Index averaged 0.47 ± 0.17 preprocedure, 0.89 ± 0.20 postprocedure, and increased by 0.15 or more in every case. Median follow-up is 20 months. There were 3 perioperative (<30 days) and 7 later failures including revision prior to any thrombosis. One patient required amputation. Four have died, 2 with patent grafts, none from causes related to VASIR, all more than 30 days post-VASIR. Estimated 1-year primary and secondary patency were 70% ± 11% and 73% ± 10%. Failure was not significantly associated with indications, comorbidities, or runoff status. There was a clear distinction between patients with early failure and the rest of the patients. None of the 8 patients with failure in the first 8 months after surgery has a patent graft. However, of 17 grafts primarily patent at 8 months, only 2 have failed (1 thrombosed and 1 required preemptive balloon angioplasty). There was a strong trend toward better patency with 6 and 7 mm diameter compared to 5 mm diameter stent grafts. Furthermore, although warfarin was not prescribed as part of the protocol, no patient taking warfarin before and who resumed warfarin after VASIR (n = 4) suffered failure. Conclusions: Despite significant early failures, we found VASIR to be durable in those who did not have early failure. Viabahn stent graft-assisted subintimal recanalization is an acceptable alternative to vein bypass in selected patients with severe SFA disease. Smaller arterial or stent graft diameter may be associated with poorer results. Warfarin may be valuable to reduce the risk of failure after VASIR.

Interventional neuroradiological techniques for the treatment of aneurysms of the supra-aortic extracranial arteries

Aneurysms in the supra-aortic extracranial arteries are rare in neurovascular pathology. Conventional surgery is effective but technically demanding and successful endovascular repair is reported. We treated 5 patients with supra-aortic extracranial artery aneurysms at our hospital (mean age 53.8 years). There were 2 aneurysms of the common carotid artery, 1 of the extracranial internal carotid artery, 1 of the subclavian artery, and 1 located at the innominate artery. Four patients were symptomatic. The lesion was the result of trauma in 3 patients. The procedure was conducted using bare stent placement and coil embolization of the aneurysm in 2 patients, covered stent in 2 patients, and bare stent only in 1 patient. No periprocedural complications occurred. Follow-up angiography revealed asymptomatic stent thrombosis in a patient treated using a covered stent, but the remaining 4 patients showed successful treatment of the aneurysms with the parent arteries remaining patent. Follow-up clinical assessment ranged between 30 and 81 months. The patient with stent thrombosis died of unrelated pathology; the remaining patients did not experience aneurysm recurrence, hemorrhage, or distal thromboembolism.

Role of superficial femoral artery stents in the management of arterial occlusive disease: review of current evidence

The objectives of this study were to compare the 1-year patency of superficial femoral artery (SFA) stent placement with percutaneous transluminal angioplasty (PTA) alone and to attempt to define the role of stents in arterial occlusive disease. Literature searches of the Embase, Medline, and Cochrane databases identified relevant articles, which were split into two subgroups: those containing case-controlled matches for stenting and PTA and those considering only stent placement. The review conformed to the QUORUM statement. One-year patency rates were 219 of 383 (57%) in the stented group and 319 of 607 (53%) in the PTA group for matched cases (odds ratio 1.206 [95% CI 0.932-1.559; p = .115]). The patency of stents deployed secondarily was 554 of 909 (61%). The combined 1-year patency of primary and secondary SFA stents for matched and unmatched case series was 816 of 1,282 (64%). One-year patency rates following stent placement or PTA alone in well-matched patient groups demonstrated no significant difference. This would suggest that the routine use of primary SFA stenting should be undertaken only in selected cases and should mainly be used in "bailout" situations or for complex lesions where surgery is precluded. However, the studies used displayed a high degree of heterogeneity, and some used stent technology that is now considered obsolete. Ongoing randomized controlled trials will provide a more definitive answer to this important problem.

Nitinol stent implantation versus balloon angioplasty for lesions in the superficial femoral artery and proximal popliteal artery: twelve-month results from the RESILIENT randomized trial

BACKGROUND

Controversy still exists regarding the best endovascular treatment strategy for patients with symptomatic disease of the superficial femoral artery. There are conflicting data regarding the benefits of superficial femoral artery stenting and the role of primary stenting compared with balloon angioplasty with provisional stent implantation.

METHODS AND RESULTS

A total of 206 patients from 24 centers in the United States and Europe with obstructive lesions of the superficial femoral artery and proximal popliteal artery and intermittent claudication were randomized to implantation of nitinol stents or percutaneous transluminal angioplasty. The mean total lesion length was 71 mm for the stent group and 64 mm for the angioplasty group. Acute lesion success (<30%residual stenosis) was superior for the stent group compared with the angioplasty group (95.8% versus 83.9%; P<0.01). Twenty-nine (40.3%) patients in the angioplasty group underwent bailout stenting because of a suboptimal angiographic result or flow-limiting dissection. Bailout stenting was treated as a target lesion revascularization and loss of primary patency in the final analysis. At 12 months, freedom from target lesion revascularization was 87.3% for the stent group compared with 45.1% for the angioplasty group (P<0.0001). Duplex ultrasound-derived primary patency at 12 months was better for the stent group (81.3% versus 36.7%; P<0.0001). Through 12 months, fractures occurred in 3.1% of stents implanted. No stent fractures resulted in loss of patency or target lesion revascularization.

CONCLUSIONS

In this multicenter trial, primary implantation of a self-expanding nitinol stent for moderate-length lesions in the superficial femoral artery and proximal popliteal artery was associated with better acute angiographic results and improved patency compared with balloon angioplasty alone.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00673985.

Endovascular stents for intermittent claudication

BACKGROUND

Endovascular stents have been suggested as a means to improve the patency of arteries after angioplasty in patients with intermittent claudication. This is an update of a Cochrane review published in 2002.

OBJECTIVES

The null hypothesis to be tested by this review is that for individuals with claudication the use of an endovascular stent, in addition to percutaneous transluminal angioplasty, does not improve symptoms of life-style limiting claudication when compared to percutaneous angioplasty alone.

SEARCH STRATEGY

For this update the Cochrane Peripheral Vascular Diseases Group searched their Specialised Register (last searched August 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (last searched 2009, Issue 3).

SELECTION CRITERIA

Randomised trials comparing angioplasty alone versus angioplasty with endovascular stents in patients with intermittent claudication.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality and extracted the data. Only published trial data were used but unpublished data were sought for the update. Effectiveness was measured by the pre-defined primary outcome measures restenosis or reocclusion rates and maximum walking distance.

MAIN RESULTS

Two studies were included involving a total of 104 participants. Both studies included only individuals with femoro-popliteal disease. They compared angioplasty and stenting with the Palmaz stent against angioplasty alone. Although one study showed a slight statistical advantage in arterial patency after angioplasty alone, this was not found when the two studies were combined. No differences in the secondary outcomes were detected in either study.

AUTHORS' CONCLUSIONS

The small number of relevant studies identified together with the small sample sizes and methodological weaknesses severely limit the usefulness of this review in guiding practice. The results from larger multicentre trials are needed.

Past, present and future of femoropopliteal stenting

Endovascular stent implantation was introduced to femoropopliteal procedures almost 2 decades ago. Initial results with balloon-expandable stainless steel stents and self-expanding Elgiloy stents, however, were disappointing. In particular, recurrence rates after long-segment femoropopliteal stenting were catastrophically high, in the range of 60% to 80% at 1 year. Also, attempts to resolve the problem of in-stent restenosis (ISR) using first-generation covered stent-grafts led to unsatisfactory results, high procedural complication rates due to large introducers, and a high incidence of graft thrombosis, which did not make these devices convincing alternatives to bare metal stents. After years of stagnation, however, recent developments in femoropopliteal stent technology have been promising. Self-expanding nitinol stents have been evaluated in several prospective studies. Initial problems with stent fractures seem to be resolved using second-generation devices; for the first time, stenting has been shown to be beneficial compared to balloon angioplasty in longer femoropopliteal lesions. Nevertheless, although superior to balloon angioplasty, nitinol stenting is still associated with a considerable restenosis rate, and treatment of ISR remains problematic. Future concepts to further improve long-term patency after femoropopliteal stenting therefore are under investigation, including drug-eluting stents, biodegradable stents, and coated stent-grafts. From a current perspective, femoropopliteal stenting remains the Achilles' heel of the interventionist.

Evolving modalities for femoropopliteal interventions

Despite technical advances in balloon design and technique, there has been little improvement of primary patency rates after balloon-based endovascular interventions for all but focal femoropopliteal lesions. Improving on stainless steel models, nitinol stents have been associated with favorable short- and midterm primary patency rates; studies with longer-term follow-up will be required to learn whether restenosis is ongoing, with continued loss of primary patency. Studies in recent years have shown varying incidences of mechanical fatigue leading to nitinol stent fracture. Covered stents are designed to prevent the tissue infiltration and intimal hyperplasia that can lead to bare metal in-stent restenosis. Several clinical studies, mainly single-center registries, have demonstrated a general effectiveness of the Hemobahn/Viabahn polytetrafluoroethylene-covered stent-grafts, approved for femoral arterial occlusive disease, and have helped to distinguish indications for use and to delineate possible failure modes. A multicenter randomized trial, which has completed enrollment, will compare the Viabahn with self-expanding bare nitinol stents. The primary use of drug-eluting stents (DES) has become routine clinical practice for coronary artery disease. The 2-phase multicenter randomized double-blind SIROCCO trials have been completed, with results published through 24 months. Follow-up demonstrated the feasibility and safety of deploying sirolimus-eluting stents in the femoropopliteal segment but failed to show superior efficacy for DES versus bare nitinol stents. However, the restenosis rates with bare metal stents were unexpectedly low. A paclitaxel-eluting stent without a polymer coating is currently being evaluated in the recently enrolled Zilver PTX randomized trial and international registry. A polymer-based everolimus-eluting stent is being evaluated for femoropopliteal use in the nonrandomized European STRIDES trial. Balloons coated with paclitaxel have recently been evaluated for simple femoropopliteal disease with encouraging results through 2 years of follow-up. The bioabsorbable stent concept emerged in response to the potential issues with metal stents, but to date no investigational device has successfully overcome issues such as relatively low radial force and variable degradation rates.

Primary stenting of the superficial femoral and popliteal artery

OBJECTIVES

Over the last decade, the number of endovascular procedures performed on the superficial femoral (SFA) and popliteal arteries (PA) has significantly increased. There is no consensus on the optimal form of intervention used in this arterial segment. While some have advocated balloon angioplasty alone, others have championed either selective or primary stenting of these lesions. It is the purpose of this study to determine the efficacy and durability of primary stenting of the superficial femoral and popliteal artery.

METHODS

All patients undergoing peripheral angioplasty by a single vascular surgeon were prospectively enrolled in an Institutional Review Board-approved, primary-stenting protocol. During a 44-month period, all patients undergoing percutaneous transluminal angioplasty of the SFA or PA also received primary arterial stenting with bare, self-expanding nitinol stents. Patient demographics and risk factors were identified. TransAtlantic InterSociety Consensus (TASC) classifications were determined for all lesions. Loss of primary patency was said to have occurred when an occlusion or a 50% or greater stenosis in any treated arterial segment was diagnosed by arterial duplex or angiography. Only time to loss of primary patency was recorded. Kaplan-Meier survival curves were plotted and differences between groups tested by log rank method.

RESULTS

Between January 16, 2004 and August 13, 2007, 201 angioplasties with primary stenting were performed on 161 patients. One hundred twenty-three stents were placed for claudication, and 78 for critical limb ischemia. Forty-six segments treated were TASC A, 82 were TASC B, 38 were TASC C, and 35 were TASC D. Patient follow-up ranged from three to 1329 days (mean: 426 days). Primary patency rates for TASC A and B lesions were 79%, 67%, and 57% at 12, 24, and 36 months. For TASC C and D lesions, primary patency rates were 52.7%, 36%, and 19% at the same time intervals. Primary patency rates for TASC A and B lesions were significantly higher than for C and D lesions (P < .001). The limb salvage rate was 88.5% in patients with critical limb ischemia. Distal runoff did not influence patency (P = .827).

CONCLUSIONS

Primary stenting of the SFA and PA provides durable results in patients with TASC A and B lesions and may be an effective treatment strategy. This approach is significantly less effective when used in treating those with TASC C and D disease. Based on the results in this series, the use of primary stenting does not extend the anatomic limits of the current treatment recommendations for catheter-based intervention in patients with infrainguinal occlusive disease.

Angioplasty versus stenting for superficial femoral artery lesions

BACKGROUND

Lower limb peripheral arterial disease (PAD) is a common, important manifestation of systemic atherosclerosis. Stenoses or occlusions in the superficial femoral artery may result in intermittent claudication as an early consequence, which may be treated by balloon angioplasty with or without stenting.

OBJECTIVES

The objective was to determine the effect of percutaneous transluminal angioplasty (PTA) when compared with PTA with stenting for lesions of the superficial femoral artery, for people with intermittent claudication or critical limb ischaemia.

SEARCH STRATEGY

The Cochrane Peripheral Vascular Diseases (PVD) Group searched their trials register (last searched February 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2009, Issue 1) for publications describing randomised controlled trials (RCTs) of percutaneous angioplasty with or without stenting.

SELECTION CRITERIA

Randomised trials of angioplasty alone versus angioplasty with stenting for the treatment of superficial femoral artery stenoses.

DATA COLLECTION AND ANALYSIS

Two authors (CT, JC) independently selected suitable trials,assessed trial quality and extracted data. A third author (AS) ranked the concealment of allocation and checked the final manuscript. The fourth author (DM) cross checked all stages of the review process.

MAIN RESULTS

Eight trials with 968 participants were included. The average age was 67 and all trials included men and women. Participants were followed for up to two years.There was a small but statistically significant improvement in primary angiographic and duplex patency at six months in patients treated with PTA plus stent over lesions treated with PTA alone (three trials and four trials, respectively). However, primary angiographic patency was non-significant 12 months (five trials, P = 0.23) and 24 months (two trials, P = 0.45). A similar but lesser effect was seen for ankle brachial pressure index (ABPI), while a more pronounced improvement in treadmill walking distance in patients with PTA plus stent insertion was observed at six and 12 (P < 0.0001), but not 24 months (P = 0.81). Only one trial reported quality of life, which showed no significant difference between patients treated with PTA alone or PTA with stent insertion at any time interval. Antiplatelet therapy protocols and inclusion criteria between trials showed marked heterogenicity.

AUTHORS' CONCLUSIONS

There is limited benefit to stenting lesions of the superficial femoral artery in addition to angioplasty, however this cannot be recommended routinely based on the results of this analysis.

Nanometer polymer surface features: the influence on surface energy, protein adsorption and endothelial cell adhesion

Current small diameter (<5 mm) synthetic vascular graft materials exhibit poor long-term patency due to thrombosis and intimal hyperplasia. Tissue engineered solutions have yielded functional vascular tissue, but some require an eight-week in vitro culture period prior to implantation-too long for immediate clinical bedside applications. Previous in vitro studies have shown that nanostructured poly(lactic-co-glycolic acid) (PLGA) surfaces elevated endothelial cell adhesion, proliferation, and extracellular matrix synthesis when compared to nanosmooth surfaces. Nonetheless, these studies failed to address the importance of lateral and vertical surface feature dimensionality coupled with surface free energy; nor did such studies elicit an optimum specific surface feature size for promoting endothelial cell adhesion. In this study, a series of highly ordered nanometer to submicron structured PLGA surfaces of identical chemistry were created using a technique employing polystyrene nanobeads and poly(dimethylsiloxane) (PDMS) molds. Results demonstrated increased endothelial cell adhesion on PLGA surfaces with vertical surface features of size less than 18.87 nm but greater than 0 nm due to increased surface energy and subsequently protein (fibronectin and collagen type IV) adsorption. Furthermore, this study provided evidence that the vertical dimension of nanometer surface features, rather than the lateral dimension, is largely responsible for these increases. In this manner, this study provides key design parameters that may promote vascular graft efficacy.

Routine stent implantation vs. percutaneous transluminal angioplasty in femoropopliteal artery disease: a meta-analysis of randomized controlled trials

AIMS

We performed a meta-analysis of randomized controlled trials comparing routine stenting (ST) with percutaneous transluminal angioplasty (PTA) for symptomatic superficial femoral-popliteal artery (SFPA) disease.

METHODS AND RESULTS

Ten trials were pooled randomizing patients to ST (n = 724 limbs) or PTA with provisional stenting (n = 718 limbs) with a follow-up period of 9-24 months. The mean lesion length was similar in the two groups (45.8 mm in the ST group and 43.3 mm in the PTA group). We calculated the summary risk ratios (RRs) for immediate technical failure, restenosis, and target vessel revascularization (TVR) using random-effects models. The immediate technical failure was higher in the PTA group than in the ST group [17.1 vs. 5.9%, respectively, RR = 0.28, 95% confidence interval (CI) = 0.15-0.54, P < 0.001], with 10.3% of the PTA patients undergoing stenting because of suboptimal result. There was a trend for lower restenosis in the ST group (37.6% in ST vs. 45.3% in PTA, RR = 0.85, 95% CI = 0.69-1.06, P = 0.146), but no difference in the need for TVR (20% in ST vs. 20.2% in PTA, RR = 0.98, 95% CI = 0.78-1.23, P = 0.89). In an analysis restricted to nitinol stents, there was a trend towards reduction in TVR (RR = 0.79, 95% CI = 0.59-1.06, P = 0.12).

CONCLUSION

Despite the higher immediate success, routine stenting was not associated with a significant reduction in the rate of restenosis or TVR. Our data do not support use of routine stenting as the primary endovascular treatment for short SFPA lesions.

Randomized, multicenter study comparing expanded polytetrafluoroethylene-covered endoprosthesis placement with percutaneous transluminal angioplasty in the treatment of superficial femoral artery occlusive disease

PURPOSE

To compare the safety and effectiveness of the Viabahn endoprosthesis with that of percutaneous transluminal angioplasty (PTA) alone in the treatment of symptomatic peripheral arterial disease (PAD) affecting the superficial femoral artery (SFA).

MATERIALS AND METHODS

From 1998 to 1999, patients with symptomatic SFA PAD were enrolled in a prospective, multicenter randomized study and underwent either PTA alone (n = 100) or PTA followed by stent-graft placement (expanded polytetrafluoroethylene/nitinol self-expanding stent-graft) (n = 97) for stenoses or occlusions of the SFA that were 13 cm long or shorter. At baseline, there were no significant differences between the PTA and stent-graft treatment groups, including chronic limb ischemia status and treated lesion length.

RESULTS

The stent-graft group had a significantly higher technical success rate (95% vs 66%, P < .0001) and 1-year primary vessel patency rate at duplex ultrasonography (65% vs 40%, P = .0003). A patency benefit was seen for lesions at least 3 cm long. At 12 months, chronic limb ischemia status was 15% further improved for the stent-graft group (P = .003). There were no significant differences between treatment groups with regard to the occurrence of early or late major adverse events.

CONCLUSIONS

In this multicenter study, the patency, technical success, and clinical status results obtained with stent-grafts were superior to those obtained with PTA alone.

[Peripheral arterial obstruction and acute lower limb ischemia]

In this article, current evidence-based treatment recommendations for acute and chronic lower limb ischemia will be presented considering the varied possibilities of endovascular techniques and open surgical vascular strategies. Beside presentation of the different therapeutic possibilities, advantages of the combination of both techniques will be described. Despite the BASIL trial, there are no prospective randomised controlled trials comparing endovascular and open surgical interventions. Different therapeutic rules along the different vascular segments will be discussed for both acute and chronic peripheral arterial disease. Generally it can be stated that aortoiliac revascularization for chronic obstructions is increasingly being carried out by endovascular means or hybrid procedures using a minimally invasive femoral approach, whereas acute occlusions in this vascular segment are still treated with open surgical techniques (Fogarty balloon thrombectomy). In the infrainguinal region, endovascular therapeutic strategies are gaining favor. However, multilevel occlusions and long-segment obstructions in the femoral and popliteal segment are still treated by bypass procedures. Acute ischemia in the infrainguinal segment is increasingly treated with endovascular methods (local thrombolysis and percutaneous thrombectomy).