According to the 24-month results from the Xpert-BTK Study, the Xpert nitinol self-expanding below-the-knee (BTK) stent (Abbott Vascular) is an efficient tool for the treatment of BTK lesions. However, angioplasty (PTA) for treatment of BTK-lesions should be the first approach, and only in case of failure or suboptimal outcomes followed by bail-out stenting with dedicated BTK stents (e.g. balloon-expandable or self-expanding), explained Dr Marc Bosiers, Belgium, in his presentation at CIRSE.
The study was a prospective, multi-centre, non-randomised clinical trial which aimed to assess the safety and performance of the 4F Self Expanding Xpert for the treatment of infrapopliteal lesions in patients with chronic critical limb ischaemia (CLI). Patients with stenotic (>50%) or occlusive BTK arteries were recruited, with a lesion length of <10cm. A maximum of two lesions in one or more BTK vessels was an essential part of the inclusion criteria, along with patients presenting with symptomatic critical limb ischaemia (Rutherford 4–6), and patients with one stenosed and patent artery were also included on the pre-condition that the stenosed artery supplies the wounded area.
Patients excluded were those with lesion lengths that required more than two stent implants, more than two infrapopliteal lesions in the same limb, previously implanted stent(s) or angioplasty (PTA) at the same lesion site, and inflow-limiting arterial lesions that were left untreated.
The study showed that at two years, primary patency was achieved in 54.4% and limb salve in 90.8% of patients (n=94: 46.8% were diabetic). Two-year survival was 71.9%. Stratifying the outcomes for lesion location (proximal vs. distal), there was no significant difference in primary patency (56.8% vs. 52.3%, respectively). However, limb salvage was significantly better for patients treated with proximal compared to distal BTK-lesions (95.1% vs. 81.1%, respectively).
The study initially ran for 12 months, then was extended for another 12 months. In the 12-month initial report (May 2005 – December 2005), 51 CLI patients were enrolled and the primary endpoint was one-year angiographic patency, as well as absence of >50% stenosis on QVA (Quantative Vessel Analysis). The 24-month extension (May 2005 – Nov 2007) study involved 94 CLI patients, and the primary endpoint was two-year duplex patency and absence of >50% stenosis. Secondary endpoint was two-year limb salvage rate.
In his concluding remarks, Bosiers said, “The Xpert stent is an efficient tool for the treatment of below-the-knee lesions. Limb salvage rates are better for proximal compared to distal lesions.”
AMS not ready for primetime
In a separate presentation, Bosiers discussed the six-month analysis of the Absorbable Metal Stent (AMS) Insight study, which showed that although AMS technology can be safely applied, it did not demonstrate efficacy in long-term patency over standard angioplasty in the infrapopliteal vessels.
The study was designed to investigate the impact of the implantation of AMS in the infrapopliteal arteries, measuring patency by angiography at six months. One hundred and seventeen patients with 149 lesions with critical limb ischaemia (CLI) were randomised to implantation of an MS (n=60, 74 lesions) or stand-alone angioplasty (n=57, 75 lesions) The primary safety endpoint was defined as absence of major amputation and/or death within 30 days after index intervention and the primary efficacy endpoint was the six-month angiographic patency rate as confirmed by core-lab QA.
| Present and future clinical view on lower limb treatment
According to the TransAtlantic Inter-Society Consensus (TASC) recommendations, recent Level-1 studies with current generation stents support the endovascular strategy for TASC A and B lesion classification for the treatment of peripheral arterial occlusive disease (PAOD), said Dr Marc Bosiers at the EuroPCR meeting held in Barcelona in May. He added that new investigational stents might further expand endovascular possibilities towards TASC C and D.
TASC A – FAST
The primary endpoint of binary restenosis on Doppler at 12 months did not differ between groups (31.7% of the stent group and 38.6% of the PTA group, p=.377). Target lesion revascularisation by one year occurred in 14.9% of the stent group and 18.3% of the PTA group (p=.595). Stent fractures had occurred by one year in 12% of patients. The conclusion reached was that among patients with SFA disease, treatment with stenting was not associated with a difference in binary restenosis at 12 months compared with balloon dilatation.
TASC B – Improved design and improved results
Following the encouraging outcomes from the RESILIENT and ABSOLUTE trials, Bosiers explained that longer stents have become available. The first generation stents were relatively short, would often overlap when required to cover total lesion length, and increased stiffness and fracture risk would occur at stent overlap. The latest generation of stents, up to 20cm in length, have the ability to minimise fracture risk. Bosiers presented the six-month interim results of the Durability trial, which was the first study to specifically test the performance of long stents (10–15cm) in long SFA lesion
TASC C and D – Will surgery be abandoned?
In regard to the future treatment of femoropopliteal arteries, for TASC A and B lesions, Bosier stated that endovascular treatment should be the first treatment choice, and for TASC C and D, surgery should be the first treatment choice. However, better design, platform improvements and new active coatings could see the future treatment of the SFA rely solely on endovascular therapy.