Residency · Residency · Interventional Radiology

Peripheral Arterial Stenting: Bare Metal vs. Drug-Eluting

Rationale for Stenting

Stenting addresses the two principal limitations of balloon angioplasty alone: elastic recoil and flow-limiting dissection. By providing a scaffold, it maintains luminal diameter. The choice between primary stenting (planned) and provisional stenting (bailout for suboptimal PTA) depends on the vascular bed and lesion characteristics.

Stent Type Comparison

Stent Design

Bare Metal Stents (BMS)

Self-expanding stents are made from nitinol (nickel-titanium alloy) and are deployed by retracting a constraining sheath. They conform to tortuous anatomy and resist external compression. Examples include the Zilver, Complete SE, SMART, and LifeStent. Self-expanding stents are the standard choice for femoropopliteal and iliac segments.

Balloon-expandable stents are made from stainless steel or cobalt-chromium and are deployed by balloon inflation. They offer precise placement and greater radial force. They are preferred at the aortic bifurcation, in iliac arteries (especially ostial lesions), and at renal and mesenteric artery origins. Examples include the Express, Palmaz, and Omnilink. Balloon-expandable stents should not be used in areas of flexion such as the femoropopliteal segment because of crush and fracture risk.

Drug-Eluting Stents (DES)

Drug-eluting stents incorporate antiproliferative agents -- paclitaxel or sirolimus/everolimus -- into the stent platform or a polymer coating. The Zilver PTX was the first FDA-approved DES for femoropopliteal disease, featuring a paclitaxel-coated nitinol self-expanding platform. The Eluvia is a polymer-coated paclitaxel-eluting stent with sustained drug release over 12 months. These stents aim to reduce in-stent restenosis by inhibiting neointimal hyperplasia.

Covered Stents (Stent-Grafts)

Covered stents consist of a bare metal stent with an ePTFE or Dacron covering. The Viabahn is a self-expanding covered stent used for femoropopliteal disease. Indications include long-segment SFA disease, perforation or rupture bailout, pseudoaneurysms, and arteriovenous fistulae. The VIASTAR trial demonstrated improved patency of the heparin-bonded Viabahn compared with BMS in long SFA lesions.

Evidence by Vascular Bed

Iliac Arteries

Primary stenting is the standard of care for iliac stenoses and occlusions. The DUTCH iliac stent trial showed that primary stenting is equivalent to provisional stenting for short lesions and preferred for longer or more complex disease. Balloon-expandable stents are preferred at the aortic bifurcation and iliac origin (kissing stents), while self-expanding stents are preferred for the external iliac artery. Long-term patency is excellent, at 85 to 95 percent at 5 years for TASC A and B lesions.

Femoropopliteal Segment

The femoropopliteal segment is the most debated territory for stenting. The ABSOLUTE trial showed superior patency for nitinol BMS over PTA in SFA lesions longer than 4 cm. For drug-eluting stents, the Zilver PTX randomized trial demonstrated improved 5-year primary patency (66.4% versus 43.4% for PTA), while the IMPERIAL trial showed Eluvia was non-inferior to Zilver PTX at 12 months, though some concern about late thrombosis emerged. For covered stents, the VIASTAR and VIBRANT trials showed the Viabahn has improved results in longer lesions (greater than 15 cm), with edge stenosis remaining a concern. The current approach favors PTA with or without DCB for most lesions, reserving stenting for suboptimal PTA results and considering DES or covered stents for long lesions or in-stent restenosis.

Infrapopliteal Arteries

Data for stenting below the knee is very limited. Most evidence supports PTA alone, with or without DCB. Coronary sirolimus-eluting stents have been used off-label with some benefit, as shown in the DESTINY and YUKON-BTK trials. The small vessel size (2-4 mm), extensive calcification, and poor runoff make tibial stenting challenging. Stenting is reserved for PTA failure with flow-limiting dissection.

The Paclitaxel Mortality Signal Controversy

The Katsanos Meta-Analysis (2018)

This study-level meta-analysis of randomized controlled trials examining paclitaxel-coated devices in femoropopliteal disease reported increased all-cause mortality at 2 and 5 years with paclitaxel devices. It led to an FDA advisory panel in 2019.

Subsequent Evidence

Individual patient-level data analyses from the IN.PACT, Zilver PTX, and other trials did not confirm a mortality signal. Multiple large registry studies and Medicare database analyses showed no increased death risk. Proposed mechanisms such as paclitaxel embolization and systemic absorption were not supported by pharmacokinetic data. The FDA concluded that benefits still outweigh risks but recommended continued long-term follow-up.

Current Status

Paclitaxel devices remain approved and widely used. Informed consent should mention the historical controversy. The debate has spurred interest in non-paclitaxel drug coatings, with sirolimus-coated balloons now emerging as alternatives.

Stent Fractures

Stent fractures are a unique problem in the femoropopliteal segment due to biomechanical stresses including flexion, torsion, and compression. They are classified from Type I (single strut fracture) through Type V (spiral or complete separation). Fractures are associated with in-stent restenosis and occlusion. Risk factors include longer stent length, overlapping stents, and stenting across joints. Fractures are minimized by accurate sizing, avoiding unnecessary stent length, and using flexible stent designs.

In-Stent Restenosis (ISR) Management

ISR occurs in 20 to 40 percent of femoropopliteal BMS at 2 years. Treatment options include PTA with DCB (the preferred first-line approach, supported by IN.PACT Global ISR data), atherectomy plus DCB (using laser or directional atherectomy for debulking prior to DCB), covered stenting as a stent-in-stent approach for recurrent ISR, and surgical bypass for multiply recurrent ISR or long-segment failure.

<image>Comparison illustration of stent types used in peripheral arterial disease. Four panels showing: (1) Self-expanding nitinol stent with a close-up of the braided or laser-cut design and arrows showing radial self-expansion; (2) Balloon-expandable stent mounted on a balloon catheter with before and after deployment views; (3) Drug-eluting stent with a magnified inset showing the polymer coating containing paclitaxel on the stent struts; (4) Covered stent-graft (Viabahn) showing the ePTFE covering over the stent skeleton. Labels indicate ideal anatomic locations for each type.</image>

<image>Anatomic diagram showing preferred stent types by vascular territory. An anterior view of the lower extremity arterial tree with color-coded zones: aortic bifurcation and iliac origins labeled for balloon-expandable stents; external iliac labeled for self-expanding stents; femoropopliteal segment labeled for self-expanding nitinol or covered stents; and infrapopliteal vessels labeled as PTA-preferred territory with stenting reserved for bailout. Key landmarks (inguinal ligament, adductor hiatus, knee joint) are marked.</image>

<image>Illustration of stent fracture classification in the superficial femoral artery. Five panels showing radiographic and schematic views: Type I single strut fracture, Type II multiple strut fractures without deformation, Type III fracture with stent deformation, Type IV fracture with complete transection and gap, Type V spiral fracture with complete separation. An inset shows the biomechanical forces (flexion, torsion, axial compression) acting on a femoropopliteal stent during leg movement.</image>

Clinical Pearls

Balloon-expandable stents should be used for precise deployment at vessel origins and bifurcations, while self-expanding stents are appropriate for long segments and areas of flexion. A balloon-expandable stent should never be placed in the SFA. Primary stenting in the iliac arteries is well supported, but in the femoropopliteal segment, a "PTA-first, stent-if-needed" or DCB strategy is preferred to minimize metal burden.

Every centimeter of stent placed in the SFA increases future treatment complexity, so the minimum stent length necessary should be used. The paclitaxel mortality signal has not been validated by patient-level data, and DES and DCBs remain important tools. Stent fractures are a real clinical problem in the femoropopliteal segment, and patients should be counseled about the importance of surveillance duplex. For in-stent restenosis, drug-coated balloon angioplasty is the current first-line approach.

References

• Schillinger M et al. Balloon angioplasty versus implantation of nitinol stents in the superficial femoral artery (ABSOLUTE trial). N Engl J Med 2006
• Dake MD et al. Durable clinical effectiveness with paclitaxel-eluting stents in the femoropopliteal artery: 5-year results of the Zilver PTX randomized trial. Circulation 2016
• Katsanos K et al. Risk of death following application of paclitaxel-coated balloons and stents in the femoropopliteal artery. J Am Heart Assoc 2018
• Secemsky EA et al. Paclitaxel-coated devices and mortality in the femoropopliteal artery. JAMA Intern Med 2020
• Nordanstig J et al. ESVS 2024 Guidelines on the Management of PAD

Read this lecture as Markdown