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

Is There an Alternative to the Surgical Above-Knee Bypass in Treatment of Superficial Femoral Artery Disease? Experiences With Viabahn Stent Graft

Objective:

We conducted a retrospective study to compare short- and mid-term patencies of Viabahn with surgical above-knee prosthetic bypass (pAKB).

Methods:

The records of 52 patients with either pAKB (n = 25) or Viabahn (n = 27) were reviewed. The majority had Rutherford clinical grade 3. Patients were followed after 3, 6, and 12 months and yearly thereafter.

Results:

For Viabahn, the short-term (1-16 months) primary patency rate was 60% with a secondary patency rate of 90%, and mid-term (1-68 months) patencies of 47% and 83.3%, respectively. In pAKB, the short-term results revealed a primary patency rate of 78% with a secondary patency of 91% and mid-term results of 65% and 90%, respectively. No statistical difference was found concerning short-term patencies. Mid-term primary patency was lower for Viabahn ( P < .05) and secondary patency proved no significant difference.

Conclusion:

Viabahn revealed similar short-term primary and secondary patencies but lower mid-term primary patency. It provides a good alternative therapy to pAKB.

Cost-effectiveness analysis of enhancements to angioplasty for infrainguinal arterial disease

Background

The aim was to perform an economic evaluation of the cost-effectiveness of endovascular enhancements to percutaneous transluminal balloon angioplasty (PTA) with bail-out bare metal stents for infrainguinal peripheral arterial disease.

Methods

The following interventions were considered: PTA with no bail-out stenting, PTA with bail-out drug-eluting stents, drug-coated balloons, primary bare metal stents, primary drug-eluting stents, endovascular brachytherapy, stent-grafts and cryoplasty. A discrete-event simulation model was developed to assess the relative cost-effectiveness of the interventions from a health service perspective over a lifetime. Populations of patients with intermittent claudication (IC) and critical leg ischaemia (CLI) were modelled separately. Univariable and probabilistic sensitivity analyses were undertaken. Effectiveness was measured by quality-adjusted life-years (QALYs).

Results

For both patient populations, the use of drug-coated balloons dominated all other options by having both lower lifetime costs and greater effectiveness. For willingness-to-pay thresholds between £0 and £100 000 per additional QALY, the probability of drug-coated balloons being cost-effective was at least 58·3 per cent for patients with IC and at least 72·2 per cent for patients with CLI. Sensitivity analyses showed that the results were robust to different assumptions regarding the clinical benefits attributable to the interventions.

Conclusion

The use of drug-coated balloons represents a cost-effective alternative to the use of PTA with bail-out bare metal stents.

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.

Endovascular stents: a review of their use in peripheral arterial disease

Technological advances in the past decade have shifted revascularization strategies from traditional open surgical approaches toward lower-morbidity percutaneous endovascular treatments for patients with lower extremity peripheral arterial disease (PAD). The continuing advances in stent design, more than any other advances, have fueled the growth of catheter-based procedures by improving the safety, durability, and predictability of percutaneous revascularization. Although the 2007 TransAtlantic Inter-Society Consensus (TASC) guidelines recommend endovascular therapy for type A and B aortoiliac and femoropopliteal lesions, recent developments in stent technology and increased experience of interventionists have suggested that a strategy of endovascular therapy first is appropriate in experienced hands for TASC type D lesions. The role of endovascular interventions is also expanding in the treatment of limb-threatening ischemia.

Heparin-bonded, expanded polytetrafluoroethylene-lined stent graft in the treatment of femoropopliteal artery disease: 1-year results of the VIPER (Viabahn Endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Artery Obstructive Disease) trial

PURPOSE

To evaluate the performance of a heparin-bonded, expanded polytetrafluoroethylene (ePTFE)-lined nitinol endoprosthesis in the treatment of long-segment occlusive disease of the femoropopliteal artery (FPA) and to identify factors associated with loss of patency.

MATERIALS AND METHODS

In a single-arm, prospective, 11-center study (VIPER [Gore Viabahn Endoprosthesis with Heparin Bioactive Surface in the Treatment of Superficial Femoral Artery Obstructive Disease] trial), 119 limbs (113 patients; 69 men; mean age, 67 y), including 88 with Rutherford category 3-5 disease and 72 with Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II) C or D lesions of the FPA, underwent stent graft implantation. The mean lesion length was 19 cm; 56% of lesions were occlusions. Follow-up evaluations included color duplex ultrasonography in all patients, with patency defined as a peak systolic velocity ratio< 2.5.

RESULTS

At 12 months, Rutherford category and ankle-brachial index (ABI) were significantly improved (mean category improvement, 2.4; ABI increased from 0.6±0.2 to 0.9±0.19; P<.0001). Primary and secondary patency rates were 73% and 92%. The primary patency for devices oversized<20% at the proximal landing zone was 88%, whereas the primary patency for devices oversized by>20% was 70% (P = .047). Primary patency was not significantly affected by device diameter (5 vs 6 vs 7 mm) or lesion length (≤20 cm vs>20 cm). The 30-day major adverse event rate was 0.8%.

CONCLUSIONS

The heparin-bonded, ePTFE/nitinol stent graft provided clinical improvement and a primary patency rate of 73% at 1 year in the treatment of long-segment FPA disease. Careful sizing of the device relative to vessel landing zones is essential for achieving optimal outcomes.

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.

Endovascular treatment of femoral-popliteal disease

Available and improved options for the treatment of femoral-popliteal disease have increased over the last decade. Even though most patients suffering from claudication due to femoral-popliteal disease are treated with aggressive medical and noninvasive methods, patients with limb-threatening disease and severely lifestyle-limiting symptoms are treated with invasive treatments, which include endovascular treatment options. Unfortunately, the unique forces involved in this vascular segment have challenged the long-term patency and clinical effectiveness of these treatments. The purpose of this brief review is to discuss treatment strategies and options for patients with femoral-popliteal disease. Included in this discussion will be the review of data from recent published studies and late-breaking trials as it pertains to certain treatment strategies.

[Evolution of stents for the treatment of femoral artery lesions]

Endovascular treatment and stent implantation in the superficial femoral artery have been proposed for over 20 years. However, the first experiments with stainless stents were relatively disappointing. The first improvement consisted in the introduction of nitinol self-expanding stents. This technology allowed an initial improvement of clinical performances, but the first generation of nitinol stents demonstrated a relatively high rate of fractures. Better knowledge of the femoral artery biomechanics and advances in technology allowed to propose a second generation of nitinol stents with improved flexibility, which decreased the rates of fracture. In-stent restenosis related to neointimal hyperplasia has also led to the development of new concepts to improve patency rates after stenting of the femoral artery: drug-eluting stents (coated-stents), biodegradable stents, and covered stents. These technologies will help to treat more complex lesions of the femoral artery in the future, with comparable results to those obtained with femoropopliteal bypasses, but we are still waiting for results of ongoing studies.

In vitro hemocompatibility of thin film nitinol in stenotic flow conditions

Because of its low profile and biologically inert behavior, thin film nitinol (TFN) is ideally suited for use in construction of endovascular devices. We have developed a surface treatment for TFN designed to minimize platelet adhesion by creating a superhydrophilic surface. The hemocompatibility of expanded polytetrafluorethylene (ePTFE), untreated thin film nitinol (UTFN), and a surface treated superhydrophilic thin film nitinol (STFN) was compared using an in vitro circulation model with whole blood under flow conditions simulating a moderate arterial stenosis. Scanning electron microscopy analysis showed increased thrombus on ePTFE as compared to UTFN or STFN. Total blood product deposition was 6.3 ± 0.8 mg/cm(2) for ePTFE, 4.5 ± 2.3 mg/cm(2) for UTFN, and 2.9 ± 0.4 mg/cm(2) for STFN (n = 12, p < 0.01). ELISA assay for fibrin showed 326 ± 42 μg/cm(2) for ePTFE, 45.6 ± 7.4 μg/cm(2) for UTFN, and 194 ± 25 μg/cm(2) for STFN (n = 12, p < 0.01). Platelet deposition measured by fluorescent intensity was 79,000 20,000 AU/mm(2) for ePTFE, 810 ± 190 AU/mm(2) for UTFN, and 1600 ± 25 AU/mm(2) for STFN (n = 10, p < 0.01). Mass spectrometry demonstrated a larger number of proteins on ePTFE as compared to either thin film. UTFN and STFN appear to attract significantly less thrombus than ePTFE. Given TFN's low profile and our previously demonstrated ability to place TFN covered stents in vivo, it is an excellent candidate for use in next-generation endovascular stents grafts.

Four-year randomized prospective comparison of percutaneous ePTFE/nitinol self-expanding stent graft versus prosthetic femoral-popliteal bypass in the treatment of superficial femoral artery occlusive disease

BACKGROUND

This is a randomized prospective study comparing the treatment of superficial femoral artery occlusive disease percutaneously with an expanded polytetrafluoroethylene (ePTFE)/nitinol self-expanding stent graft (stent graft) versus surgical femoral to above-knee popliteal artery bypass with synthetic graft material.

METHODS

One hundred limbs in 86 patients with superficial femoral artery occlusive disease were evaluated from March 2004 to May 2005. Patient symptoms included both claudication and limb threatening ischemia with or without tissue loss. Trans-Atlantic InterSociety Consensus (TASC II) A (n = 18), B (n = 56), C (n = 11), and D (n = 15) lesions were included. Patients were randomized prospectively into one of two treatment groups; a percutaneous treatment group (group A; n = 50) with angioplasty and placement of one or more stent grafts, or a surgical treatment group (group B; n = 50) with a femoral to above-knee popliteal artery bypass using synthetic conduit (Dacron or ePTFE). Patients were followed for 48 months. Follow-up evaluation included clinical assessment, physical examination, ankle-brachial indices, and color flow duplex sonography at 3, 6, 9, 12, 18, 24, 36, and 48 months.

RESULTS

Mean total lesion length of the treated arterial segment in the stent graft group was 25.6 cm (SD = 15 cm). The stent graft group demonstrated a primary patency of 72%, 63%, 63%, and 59% with a secondary patency of 83%, 74%, 74%, and 74% at 12, 24, 36, and 48 months, respectively. The surgical femoral-popliteal group demonstrated a primary patency of 76%, 63%, 63%, and 58% with a secondary patency of 86%, 76%, 76%, and 71% at 12, 24, 36, and 48 months, respectively. No statistical difference was found between the two groups with respect to primary (P = .807) or secondary (P = .891) patency.

CONCLUSION

Management of superficial femoral artery occlusive disease with percutaneous stent grafts exhibits similar primary patency at 4-year (48 month) follow up when compared with conventional femoral-popliteal artery bypass grafting with synthetic conduit. This treatment method may offer an alternative to treatment of the superficial femoral artery segment for revascularization when prosthetic bypass is being considered or when autologous conduit is unavailable.

Outcomes of covered kissing stent placement compared with bare metal stent placement in the treatment of atherosclerotic occlusive disease at the aortic bifurcation

PURPOSE

To review the outcomes with the use of balloon-expandable covered iliac kissing stents as compared with bare metal stents in the treatment of atherosclerotic disease at the aortic bifurcation.

MATERIALS AND METHODS

A review of consecutive patients from a single institution with atherosclerotic occlusive disease at the aortic bifurcation treated with balloon-expandable kissing stents was performed between January 1, 2002, and September 1, 2007. Fifty-four patients were identified and divided into two groups: those with bare metal stents and those with covered stents. Technical and clinical success (Fontaine classification), complications, and patency at follow-up were documented.

RESULTS

Twenty-six patients (17 men, nine women; mean age, 61 years; age range, 39-79 years) received covered stents and 28 patients (15 men, 13 women; mean age, 61 years; age range, 38-82 years) received bare metal stents. Technical success was achieved in 100% of patients in both groups. Major complications occurred in three of the 26 (11%) with covered stents (P = .66) and two of the 28 patients (7%) with bare metal stents. The median follow-up was 21 months (20 months for covered stents vs 25 months for bare metal stents; range, 1-62 months). Twenty-two of the 26 patients (85%) with covered stents had sustained improvement in clinical symptoms during the follow-up period compared with 15 of the 28 patients (54%) with bare metal stents (P = .02). Primary patency rates at 1 and 2 years were 92% and 92%, respectively, for covered stents and 78% and 62% for bare metal stents (P = .023).

CONCLUSIONS

The use of covered balloon-expandable kissing stents for atherosclerotic aortic bifurcation occlusive disease provides superior patency at 2 years as compared with bare metal balloon-expandable stents.

Treating the diseased superficial femoral artery

Vascular disease involving the superficial femoral artery (SFA) is common. Once the decision to treat the SFA is made, the benefits and limitations of angioplasty and stents must be applied to each specific patient. Additionally, the potential role of covered stents as well as drug eluting stents must be considered.

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.

[New stent developments for peripheral arterial occlusive disease]

Infrainguinal peripheral occlusive disease is increasingly being treated by endovascular techniques. Bare metal stainless steel, self-expanding nitinol stents, drug-eluting and covered stents (stent grafts) are becoming increasingly more important adjuncts to percutaneous translumninal angioplasty in the treatment of peripheral artery disease. In this article the available evidence supporting the use of stents in the femoropopliteal and tibial arteries will be described as well as their limitations. Future stent developments will also be discussed.

[Surgical treatment of atherosclerosis in the lower limbs]

BACKGROUND

Walking exercise, smoking cessation and best medical therapy are cornerstones in all treatment of atherosclerosis. For patients with intermittent claudication or critical limb ischemia, endovascular therapy (which has developed substantially during the last decade) has become the first line treatment (when feasible). The aim of this article is to provide an overview of options for surgical treatment of peripheral atherosclerosis in the lower limbs.

MATERIAL AND METHODS

The article is based on literature identified through a non-systematic search in PubMed, vascular textbooks and the authors' own clinical experience.

RESULTS

When endovascular therapy has failed or is not feasible, open surgical techniques are used, such as endarterectomy and bypass surgery to the popliteal or distal arteries. Hybrid procedures, with femoral endarterectomy and distal or proximal endovascular intervention, are often used. Increased use of endovascular treatment reduces the procedural time, length of hospital stay and the rate of complications. In patients with extreme disease progression, primary amputation may still be the treatment of choice.

INTERPRETATION

Surgical treatment of peripheral artery disease requires competence both within radiological intervention and open surgical treatment modalities.

Primary nitinol stenting for femoropopliteal disease

The 1- to 2-year primary patency rates associated with self-expanding nitinol stents for the treatment of symptomatic femoropopliteal disease are superior to those for percutaneous transluminal angioplasty (PTA) and the first-generation stainless steel balloon-expandable stents. The advantages of nitinol stents include improved radial strength and flexibility, the ability to recover from being crushed, reduced foreshortening, and (importantly) deployability without balloon dilation of the stent edge (which may decrease the incidence of the edge stenosis, or "candy-wrap" effect, often observed with balloon-expandable stents). The technical success rate associated with primary deployment of nitinol stents is very high, and acute to 6-month patency results are predictably excellent. Prior to the introduction of nitinol stents, the original guidelines (2000) of the multidisciplinary TransAtlantic Inter-Society Consensus (TASC I) recommended only an adjunctive role for femoropopliteal stents following suboptimal PTA. The abbreviated 2007 TASC II report essentially extended this recommendation to nitinol stents. Here, current trials of nitinol stenting in the femoropopliteal segment are discussed, with emphasis on the advantages of primary (and often direct) deployment in selected circumstances dependent on factors including lesion length, lesion location, indication for treatment (critical limb ischemia or claudication, in-stent restenosis, stent-graft restenosis), and the relative appropriateness of other modalities (e.g., covered stents). Technical considerations in primary nitinol stenting are briefly reviewed. Open questions regarding the factors involved in nitinol stent fracture and the possible association of fracture and restenosis are examined in the context of current clinical trials. A new generation of femoropopliteal nitinol stents combining superior durability and flexibility is expected soon. Development and implementation of uniform reporting and surveillance standards is important for optimizing current and future research.

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.

Revascularização endovascular infrainguinal: fatores determinantes para a perviedade

Contexto: A terapia endovascular tem avançado muito como tratamento para a doença arterial oclusiva infrainguinal, principalmente com o desenvolvimento dos materiais e dos stents autoexpansíveis de nitinol. Objetivo: Avaliar os resultados e os fatores determinantes da angioplastia fêmoro-poplítea em pacientes portadores de isquemia de membros inferiores. Métodos: Foram tratados, através de angioplastia com ou sem stent, 114 pacientes, e acompanhados por um período médio de 12 meses. A média de idade foi de 66 anos; 53% eram do sexo feminino; 23,7% eram portadores de claudicação incapacitante; 8,8%, de dor isquêmica de repouso; e 67,5%, de lesão trófica. As lesões foram classificadas segundo o TransAtlantic Inter-Society Consensus II em A (53%), B (34%), C (5%) e D (9%). Resultados: A análise angiográfica do leito distal mostrou uma média de 1,4±1,0 artérias infrapoplíteas pérvias. O sucesso inicial foi de 97%. No seguimento de 1, 6, 12 e 24 meses, a perviedade primária foi de 94, 78, 48 e 31%, e a primária assistida, de 94, 84, 73 e 61%, respectivamente (p = 0,005). O leito distal pobre e a presença de diabetes melito foram associados a uma menor perviedade primária (p = 0,01), enquanto a extensão da lesão não influenciou os resultados. As taxas de salvamento de membro em 6, 12 e 24 meses foram de 95, 90 e 90%, respectivamente. Conclusões: A extensão das lesões tratadas não foi um fator determinante em nossa casuística para o menor sucesso da angioplastia, o que pode sugerir que as indicações para o tratamento endovascular possam ser ampliadas para pacientes com lesões TransAtlantic Inter-Society Consensus II C/D.