Should We Routinely Stent the Femoropopliteal Artery? An Interventionalist`s Perspective

Abstract: Stenting of femoropopliteal (FP) arterial disease is currently the most common strategy adopted by endovascular specialists. Several randomized trials have shown that stenting with nitinol self-expanding stents leads to less restenosis on intermediate-term and long-term follow-up when compared with plain old balloon angioplasty (POBA) and provisional stenting. In this overview, we present the pros and cons of primary stenting of FP arteries vs alternative approaches including provisional stenting following POBA, atherectomy and/or drug-coated balloons, and how these initial non-stent strategies play a significant role in treating FP arterial disease.

J INVASIVE CARDIOL 2015;27(11):E258-E261

Key words: femoropopliteal, drug-coated balloons, scoring balloons, atherectomy, stent, target lesion revascularization, patency, restenosis, drug-eluting stents

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Over the past few years, there has been exponential growth in the endovascular treatment of femoropopliteal (FP) arterial disease.¹ With this growth, numerous emerging technologies have become available to the endovascular specialist, allowing treatment of most lesions with high acute procedural success. The durability of the treatment, however, has been negatively influenced by high rates of restenosis and repeat target lesion revascularization (TLR), which are predicted by treating long lesions, total occlusions, Trans Atlantic Inter-Societal Consensus (TASC)-D lesions, smaller vessels, and diabetics, as well as the time from index procedure.²  

Primary stenting strategies can be accomplished by nitinol self-expanding bare-metal stent (BMS), non-polymer based drug eluting stent (np-DES), polymer-based drug-eluting stent (p-DES), and bioresorbable DES (b-DES) implantation. Several BMSs and the Zilver PTX (Cook Medical) np-DES are currently available and approved to treat FP arteries in the United States. Dedicated p-DES and b-DES to treat FP arteries are currently not available and are still undergoing development and testing. Primary stenting of the FP artery was compared with plain old balloon angioplasty (POBA) in several randomized trials.^3-7 Primary BMS did reduce restenosis rates significantly at 1-year follow-up when compared with the provisional stenting strategy. This finding was most pronounced in long lesions rather than short ones (Figure 1). When intraprocedural provisional stenting was not considered as a TLR, TLR was not altered significantly with primary BMS. The reduction in TLR was only seen with the Zilver PTX np-DES (mean lesion length, 6.3 mm) (Figure 2). 

TLR reduction with primary BMS implantation was only noted when provisional stenting in the POBA arm was considered a TLR. This method of analysis has recently been seen as part of premarket approval (PMA) applications in the United States. This allows the testing strategy to compare outcomes with POBA (alone with no provisional stenting) to primary stenting. Considering the high rate of stenting with POBA, one expects that the TLR rate in the POBA arm would be high using this method of analysis, leading to superior results with primary stenting. From a practical standpoint, however, provisional stenting should not be considered a TLR if one is comparing a strategy of primary stenting vs a no-stent strategy with provisional stenting, since the main goal is to reduce the rate of stenting while preserving good long-term outcome. 

Although restenosis is likely to lead to TLR, the correlation between the two endpoints is weak. Lesions over 50% are considered restenotic by duplex ultrasound or angiography, but if they fall in the moderately severe range (50%-70%) they may not lead to symptoms or clinically-driven TLR (CD-TLR). We plotted data on the percentage of patients with restenosis at 1-year follow-up from five trials^3-7 randomized to primary stenting or POBA with provisional stenting against the percentage of the same patients who underwent TLR during the same follow-up period. This showed a positive but weak correlation between restenosis and TLR (Figure 3). This could explain why restenosis does not necessarily mean CD-TLR, with the latter having more clinical relevance. Similarly, in the coronary intervention area, investigators have moved away from restenosis as an endpoint to target lesion failure (TLF) (a combined endpoint of TLR, cardiac death, or non-fatal myocardial infarction related to lesion failure). A relevant TLF endpoint in peripheral arterial interventions would be the combined endpoint of TLR, vascular death related to treated lesion, or amputation of treated limb. TLF will also likely be mostly influenced by TLR. 

Primary stenting also does not lead to a significant change in quality of life or in the Rutherford-Becker class at 1 year when compared to POBA with provisional stenting. In addition, walking distance and amputation rates were not consistently improved in all studies and mortality was not altered between the two strategies.^3-7 Furthermore, stenting in general has its own problems, including stent fractures,⁸ continued loss of patency over time (particularly with long lesions), and a very difficult problem to treat when in-stent restenosis (ISR) develops. ISR is often diffuse and lesions are thrombotic-restenotic when stents are totally occluded, a finding associated with high rate of distal embolization.^9-11 Quite often, additional stents are needed to treat ISR, leading to multilayered stents within the FP segment, the clinical impact of which remains unknown. Finally, stenting may impair future surgical targets. 

The initial non-stent approach can be tailored to the operator’s experience, availability of and comfort with various devices, and budget constraints. There are some advantages and disadvantages to the initial choice of the non-stent strategy. 

Balloon angioplasty. As noted above, POBA with provisional stenting has been shown to have the same TLR rate as primary stenting, with no significant change in Rutherford-Becker class and quality of life and inconsistent results on walking distance. The use of drug-coated balloon (DCB) with provisional stenting is, however, likely to increase. Several trials comparing POBA to DCB with provisional stenting in treating FP lesions showed a significant improvement in TLR at 12-24 months of follow-up with DCB (Table 1).^12-17 However, balloon angioplasty, POBA or DCB, is likely to be associated with a high rate of stenting overall. Moving to a strategy of reducing stenting followed by DCB will likely be more consistent with an optimal approach to treat FP lesions. 

Atherectomy. Atherectomy using the SilverHawk (Covidien) or the Diamondback 360 (Cardiovascular Systems, Inc) has been shown to reduce stent rate when compared to POBA without atherectomy. This has been demonstrated in three small randomized trials^18-20 with consistent results of: (1) lower maximum balloon pressure to yield full balloon inflation post atherectomy compared to POBA alone (ie, improve vessel compliance); (2) lower dissection rate; and (3) less stenting. TLR is not significantly improved with atherectomy and adjunctive POBA compared to POBA alone, although in the Calcium 360 trial¹⁸ major adverse events were less frequent after orbital atherectomy compared to POBA alone and TLR trended lower after atherectomy. The importance of atherectomy is in changing vessel compliance and reducing dissections and therefore reducing the need for stenting (Figure 4) after adjunctive DCB, thereby accomplishing the goal of less stenting and lower TLR rate. 

Specialized balloons. Specialized balloons, namely the Angiosculpt (Spectranetics, Inc) and the Chocolate balloon (TriReme Medical, Inc), are designed to reduce dissection rate when compared to POBA. These balloons are now drug coated (not available in the United States) and they may be able to achieve the dual role of reducing TLR and stenting. Applications of the drug-coated Angiosculpt in a porcine coronary model have shown a marked reduction in late lumen loss.²¹

Drug-coated balloons vs drug-coated stents. A recent review of DCB and DES in FP interventions indicated that DCBs are likely to yield the same clinical outcome as DESs.²² No randomized trials have compared these two drug delivery systems with regard to clinical outcomes.  

Provisional stenting is therefore a viable approach to treat FP lesions, and with the advent of DCB it is more likely to be adopted as an initial strategy. This is particularly true for the common femoral and popliteal arteries, where routine stenting is not favorable. In these “no-stent zones,” stents are subject to continuous flexion, compression, extension, contraction, and torsion, with likely negative long-term consequences on stent integrity and overall patency. Stent expansion is also an issue with calcified popliteal arteries, and stent radial strength may not be optimal although the Supera stent (Abbott Vascular) was recently shown to be kink resistant, with no fractures in FP segments.²³ Rastan et al⁷ have also shown that angioplasty with provisional stenting of the popliteal artery with the LifeStent has the same TLR rate as primary stenting when provisional stenting was not considered as a TLR. In this randomized trial, there were no significant differences between the two strategies for primary patency (67.4% vs 65.7%; P=.92) or a significant change in the improvement in the Rutherford-Becker class (P=.31). Finally, stenting the popliteal or common femoral arteries may negatively affect patients’ future surgical options. Our approach to treating the popliteal and common femoral arteries remains an initial no-stent strategy with adjunctive drug-coated balloons, which is similar to the initial approach we adopted for treating the entire FP segment. 

Conclusion

Provisional stenting with BMS has the same TLR and quality of life when compared to primary stenting of the FP segment. However, provisional stenting or primary stenting with DES has improved clinical outcomes compared to primary stenting with BMS or provisional stenting with BMS in short lesions. DCBs are likely, however, to yield similar effectiveness as drug-coated stents but are likely to be associated with a higher rate of provisional stenting. Reducing bail-out stenting with atherectomy prior to DCB or potentially the application of drug-coated Angiosculpt or Chocolate balloon may yield good clinical outcomes with a reduced stent rate in treating FP lesions. Further studies are needed to confirm these strategies, particularly in high-risk subgroups including long lesions, chronic total occlusions, severely calcified vessels, TASC-D occlusions, restenotic lesions, and diabetics. 

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From the ¹Midwest Cardiovascular Research Foundation, Davenport, Iowa; and the ²VA Medical Center, Dallas, Texas.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Shammas received relevant research and education grants from Boston Scientific, Spectranetics, CSI, Medtronic, Cordis, and Bard. Full disclosure may be found at www.mcrfmd.com. Dr Banerjee reports no conflicts of interest regarding the content herein.

Manuscript submitted January 7, 2015, provisional acceptance given January 8, 2015, final version accepted January 13, 2015.

Address for correspondence: Nicolas W. Shammas, MD, MS, FACC, FSCAI, President and Research Director, Midwest Cardiovascular Research Foundation, Adjunct Clinical Associate Professor, University of Iowa Hospitals and Clinics, Consultant and Interventional Cardiologist
Cardiovascular Medicine, PC, 1236 E. Rusholme Street, Suite 300, Davenport, IA 52803. Email: shammas@mchsi.com