What is the level of evidence for stenting in the superficial femoral artery?

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Professor Johannes Lammer, from the Department of Radiology, University Hospital, Vienna, Austria, and President of CIRSE (Cardiovascular and Interventional Radiological Society of Europe), has drawn the attention of Vascular News to the level of evidence evaluating whether percutaneous transluminal angioplasty of the superficial femoral artery is a sufficient stand alone treatment in terms of clinical and technical success rates, or whether combined angioplasty and stenting demonstrates superior results.

To begin, Lammer says that revascularisation of the angioplasty is the most frequently performed endovascular procedure. With the development advancing techniques as well as more sophisticated stenting material and balloons, endovascular treatment is nowadays not just a treatment option but, in most cases, preferable, at least as an initial revascularisation procedure in the treatment of peripheral arterial vascular disease. Over the past ten years, the question of when to stent has been a matter for discussion, said Lammer.

Given the literature, clinical indications for angioplasty revascularisation include patients presenting with intermittent claudication after risk factor modification and exercise training without significant improvement of the walking distance. These anatomic indications are defined by the TransAtlantic Inter-Society Consensus (TASC) working group, shown in Table 1, left.

Lammer compared angioplasty of the superficial femoral artery against the bare metal stent and is interested in the level of evidence by refering to a series of relevant studies, including the meta-analysis by Muradin et al, entitled ‘Balloon dilation and stent implantation for treatment of femoropopliteral arterial disease: meta-analysis’.

Lammer explained that the technical and clinical success rates of angioplasty of femoropopliteal artery stenoses in all reports included in the meta-study exceeds 95% (range 98-100%, standard error 1.0%), as explained by Muradin et al. He also stated that device developments such as hydrophilic guide wires and technical developments, such as subintimal recanalisation, provides high recanalisation rates in total occlusions of more than 85% (range 81-94%, standard error 2.9%), as shown by London et al.

The mid- and long-term results of angioplasty versus stenting of the superficial femoral artery were highlighted in a series of various case reports and Lammer explains that risk factors for recurrence were analysed by multivariate stepwise backward regression. Clinical stage of the disease (intermittent claudication vs. critical limb ischaemia), length of lesion and outflow disease were most commonly addressed as independent risk factors for restenoses. The results were reported by Muradin et al and are shown in Table 2.

In Muradin’s meta-analysis, 19 studies met the inclusion criteria which represented 923 balloon dilations and 473 stent implantations. Combined three-year patency rates for angioplasty stenoses in patients with intermittent claudication after balloon dilation was 61%. For angioplasty and occlusions in intermittent claudication patients, the patency rate was 48%. Patients with critical limb ischaemia, at three years results were 43% and 30% for angioplasty and stenosis and angioplasty and occlusions respectively. After stent implantation, the three-year patency results for patients with intermittent claudication and stent and stenosis was 66% and 64% for stent and occlusion. For patients with critical limb ischaemia, the results for stent and stenosis and stent and occlusion was 65% and 63% respectively. From this, it could be devised that the results of stent implantation seem more favourable.

Five randomised trials (Vroegindeweij, Grimm, Cejna, Becquemin and Grenacher) comparing angioplasty versus angioplasty with stenting in the femoropopliteal artery segment were published between 1997 and 2004. In these trials, according to Lammer, Palmaz stainless steel stents or the Wallstent were used, and only TASC A lesions were treated. The one-year primary patency rates were 63-74% in the angioplasty groups and 62% vs. 66% in the stent groups. From the results of these trials, Lammer concluded that there is no significant difference seen between angioplasty and stenting.

Recently, Schillinger et al published a single-centre randomised trial comparing angioplasty versus stenting with nitinol stents of TASC A and B lesions of the femoropopliteal artery in patients with peripheral arterial disease. The study, ‘Balloon angioplasty versus implantation of nitinol stents in the superficial femoral artery’, involved 104 patients who had severe claudication or chronic limb ischaemia due to stenosis or occlusion of the angioplasty. Fifty-one randomised patients were assigned to stent implantations and 53 patients underwent angioplasty. Restenosis rates (>50%) and clinical outcomes were assessed at six and 12 months post-intervention. The average length of the treated segments as Lammer reports was 132 +/- 71mm in the stent group and 127 +/- 55mm in the angioplasty group. In the angioplasty group, secondary stenting was performed in 17 patients (32%) due to suboptimal results after balloon dilation. Restenoses rates of patients in both groups are presented in Table 3 above.

It was observed that patients in the stent group had a lower restenoses rate than those in the angioplasty group at both six and 12 months. Clinically, Schillinger et al found that patients in the stent group had a significantly higher maximum treadmill walking capacity compared to the angioplasty group at six months (mean 363m vs. 270m respectively, p=0.041) and at 12 months (mean 387m vs. 267m respectively, p=0.040).

Citing the FAST (Femoral Artery Stent Trial) trial (Krankenberg et al), Lammer discussed the results of a randomised multi-centre trial that compared angioplasty and nitinol stents in 214 patients with peripheral arterial disease. One hundred and nine patients were assigned to angioplasty and 105 patients to primary stenting. The lesion length was 4.6cm in the angioplasty group and 4.4cm in the stent group. After colour duplex ultrasound at six and 12 months, the restenosis rates were both higher in the angioplasty group, however, as Lammer concluded, this trial could not demonstrate any significant superiority of primary stenting of superficial femoral artery lesions.

After evaluation of the evidence, Lammer summarised by stating that “there is still no clear evidence whether angioplasty first with secondary stenting is needed or primary stenting of TASC A and/or B lesions of the femoropopliteal artery is the treatment choice.”

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