PARTICIPANTS

Craig Walker, MD, is Clinical Professor of Medicine at Tulane Medical School and Clinical Professor of Medicine at LSU Medical School in New Orleans, Louisiana, and an interventional cardiologist at the Cardiovascular Institute of the South in Houma, Louisiana. He stated that he has no financial interests related to this article. Dr. Walker may be reached at (800) 445-9676; craig.walker@cardio.com.

Joseph J. Ricotta II, MD, MS, is Chair of Vascular Surgery and Medical Director of Northside Hospital Heart and Vascular Institute in Atlanta, Georgia. He stated that he has no financial interests related to this article. Dr. Ricotta may be reached at (404) 303-3615; joseph.ricotta@northside.com.

With this year's US Food and Drug Administration approval of the Supera® peripheral stent system (Abbott Vascular), interventionists across the United States have had the chance to use a truly unique tool for femoropopliteal disease. Endovascular Today recently asked two leading endovascular specialists, Craig Walker, MD, and Joseph J. Ricotta II, MD, MS, to discuss how and why they use vascular mimetic implants to treat lesions in the superficial femoral (SFA) and proximal popliteal arteries. Their perspectives and recommendations of this unique class of technology are based upon both the relevant clinical evidence and their own experience.

COMBINING THE IDEAL ATTRIBUTES OF AN SFA TREATMENT

Dr. Walker: The first time I felt an early prototype of Supera® (Figure 1) in 2007, I knew it was something special. The design was so simple and yet so robust that I knew immediately it could be a great solution for the SFA, which experiences high stresses and strains from its constant motion.

The Supera® implant has a design that is completely different from laser-cut standard nitinol stents. It has six interwoven nitinol wires in a closed-loop design with ends that are welded; this produces an implant that is incredibly strong, fracture resistant, and yet flexible. This allows the artery to move naturally without being hindered. Because it's so different from standard nitinol stents and because it mimics the movement of the artery so well, I believe a more appropriate term to describe this class of technology is vascular mimetic implant.

Dr. Ricotta: I agree that preserving the natural movement of the anatomy is critical to ensuring durable clinical outcomes. A natural-moving mimetic implant such as Supera® can more comprehensively address the common issues that we see with the current modalities of SFA treatment.

The ideal stent should emulate an artery's natural flexibility while also standing up to the forces of flexion, extension, compression, and torsion. The Supera® implant achieves this due to its novel design, which not only resists kinking and recoil (Figure 2), but also has incredible compression resistance. Testing has shown that Supera® has four to five times the compression resistance of all other standard nitinol stents.1 The woven design and high compression resistance also result in a very round, open vessel after implantation, preserving a maximization of luminal gain.

Dr. Walker: That's one of the biggest surprises to me—the round lumens after deployment. I perform a great deal of imaging with both intravascular ultrasound and optical coherence tomography, and I have been struck with how round the lumens always end up. My neighbor here in Louisiana, Frank Arena, MD, actually published an article analyzing lumen symmetry after stenting with Supera® versus standard nitinol stents last year in the Journal of Vascular Medicine & Surgery.2 He found that with Supera®, the lumens were almost perfectly symmetric (round), even in severe calcification (Figure 3). I believe this is because of the high compression resistance of Supera®.

Dr. Ricotta: High degrees of flexibility and strength are important, but we're forgetting one key attribute that helps make this implant different—it has almost no chronic outward force (Figure 4). In recent years, we have become more familiar with this term and the concept of chronic outward force. Chronic outward force occurs because standard nitinol stents are oversized to the vessel diameter by 10% to 40% and subsequently push outward on the vessel wall with a constant force to try to reach their equilibrium state. This outward force is believed to irritate the vessel and may be a catalyst for accelerated formation of neointimal hyperplasia. We've adjusted down our oversizing with some devices, such as covered self-expanding stents, but Supera® has an innate advantage for two reasons: (1) its woven design has minimal outward force, and (2) it's also sized 1:1 with the vessel.

Dr. Walker: That's right, Dr. Ricotta. That's one reason there are limitations with drug-eluting peripheral stents; even if these laser-cut stents were to have a paclitaxel coating, the fundamental mechanical structure is still a standard nitinol stent. Once the drug is gone after 2 or 3 days, a bare-metal standard nitinol stent remains and imposes a persistent chronic outward force on the vessel.

CLINICAL DATA

Dr. Walker: I had faith that this design would work well in the SFA even before the robust clinical evidence came out. Since the SUPERB trial data3 have been released, we've learned even more about this device, and they have affirmed our hypotheses. Even before I saw the clinical data, I really believed in the design because I had felt the device and knew it combined the appropriate properties to help revolutionize SFA treatment.

Dr. Ricotta: I agree with Dr. Walker. When initial data were released in late 2012 and early 2013,4 people really took notice of this device. The Leipzig studies5,6 in particular really caught my eye.

The SUPERB pivotal trial achieved an excellent 12-month primary patency rate of 86.3% (Kaplan-Meier [K-M]). Freedom from reintervention (target lesion revascularization [TLR]) was also excellent at 89% (1 year) and 84% (2 years). This was in a relatively tough patient population that consisted of 45% of patients with severe calcium and 25% with total occlusions.3

Dr. Walker: SUPERB's subset analyses3 really impressed me. First was the consistency in outcomes across lesion lengths (Figure 5). Generally, there is a drop in performance as lesions get longer. However, in both the short-lesion tercile and long-lesion tercile of SUPERB, the percentage of patients without restenosis was the same at 88%. I have never seen that before in any SFA device trial, including covered stent trials.

Dr. Ricotta: The data that most impressed me were the outcomes when Supera® was deployed nominally, rather than compressed or elongated deployments. In proper deployments of Supera® (where it was deployed to labeled stent length ± 10%), primary patency was 90.5% at 12 months.3

In addition, nominal deployment achieved 97% and 96% freedom from reintervention rates at 1 and 2 years, respectively. However, we found that lower primary patency and freedom from reintervention rates (TLR) were associated with severely elongated deployments. That's why it is important to deploy properly and size appropriately to optimize Supera® nominal deployment.3

Dr. Walker: I agree. In deploying Supera® nominally, you can really get outstanding results. I was also recently made aware of the SUPERB data in severe calcium (Table 1). Forty-five percent of the patients in the SUPERB trial had severe calcification.3 In those patients, the 12-month patency was 89% (VIVA [binary] method), and the freedom from reintervention rate was 95%. At 24 months, this number decreased only slightly to 92%.7 The similarities between 12- and 24-month data show that this is really a durable solution.

This is significant because we know that calcium is one of the environments that standard nitinol stents do not work well in. Furthermore, calcium inhibits drug uptake. I believe that is one reason the recent drug-coated balloon pivotal trials were designed to exclude severe calcification. In my experience with Supera®, I've found it to be the ideal solution for calcified lesions due to its compression resistance and flexibility.

Dr. Ricotta: Another reason the outcomes may be so good is because the stent very rarely experiences fracture. In fact, across all 1,400 United States and international patients treated in trials and registries with Supera®, none have had a fracture at 1 year.8-14 This is a huge benefit, and it gives me great peace of mind when I implant the Supera® in my patients.

A DIFFERENT CLASS OF IMPLANT, A DIFFERENT DEPLOYMENT MECHANISM

Dr. Ricotta: The design of Supera® requires a different type of delivery mechanism. Because the implant is woven and has such high compression resistance, it is not crimped down on the deployment catheter. Instead, it's stretched out within the catheter, and a stent driver within the catheter pushes short segments of the implant out of the delivery system.

Dr. Walker: Some physicians have the perception that it's a difficult delivery system. In my opinion, it's not difficult—it's just different. Because it's a two-handed deployment, there is a slight learning curve, but in the end, I strongly believe the clinical results you can achieve with Supera® make it worthwhile.

Dr. Ricotta: I believe great outcomes are easily achieved if you follow a few simple guidelines. The most critical step is lesion preparation. I predilate the vessel carefully by inflating the balloon for a long time: 2 to 3 minutes. When I choose a balloon, I size 1:1 according to the reference vessel diameter. Also, I make sure to predilate 1 cm above and below the lesion.

Dr. Walker: That's the algorithm I use, as well. At this point in a procedure, I use road map imaging to help determine the diameter of the predilated lesion and choose the right diameter Supera® to use. It's my goal to use a Supera® that matches the diameter of the predilated vessel 1:1. All areas of the artery that will be treated with Supera® should be predilated at least to the outer diameter of the device that will be implanted. In essence, thorough lesion preparation and implant sizing are absolutely critical to achieving nominal deployment.

Dr. Ricotta: I most often use a 6-mm semicompliant balloon before implanting a 5.5-mm Supera®. During deployment, it is important to increase imaging magnification, watch the cell geometry, and deploy slowly. Short, slow, even pushes of the thumb slide give you more control over cell geometry as you pave the vessel with Supera®. A good reference for cell geometry is to compare Supera® in vivo with Supera® on your tabletop (nominal length). As we've discussed, nominal deployment helps to optimize compression resistance, maximize luminal gain, and yield excellent clinical outcomes.

PRACTICAL APPLICATIONS: WHEN I USE SUPERA®

Dr. Ricotta: We are fortunate to have such an array of great tools for the SFA today. Supera® has been a game-changer in my practice. I've found that it's an excellent tool for both routine SFA lesions and extremely challenging, calcified occlusions. If I have a calcified lesion, I use Supera® as a frontline therapy (Figure 6). The only exception is if the lesion is in the proximal SFA, within 2 cm of the ostium.

Dr. Walker: It has been an incredibly exciting time to be able to combine the knowledge gained from the SUPERB trial with our clinical experiences. That's why I also use Supera® in a wide variety of SFA and proximal popliteal lesions, from focal to challenging. In particular, Supera® is a great tool for calcified lesions. I have found Supera® to be an effective solution in my practice versus atherectomy, which can cause perforation of the vessel wall and potentially increased radiation exposure due to longer procedure times.

A theme I've heard associated with Supera® is “Change the Rules.” I believe this is very appropriate because this implant changes the rules for SFA stenting. It has both the greatest radial strength (ie, compression resistance) and the greatest flexibility of any peripheral stent available today.1 Strength and flexibility are two properties that are typically design tradeoffs; one must sacrifice one to achieve the other.

Dr. Ricotta: Changing the rules also means that with the Supera® vascular mimetic implant, we need to think about predilatation and sizing a little differently. The key to good deployment is really all about ensuring the vessel is well prepared and 1:1 sizing. Again, once deployment has been initiated, delivering the implant more slowly is the key to success.

Dr. Walker: I also think the durable clinical results speak for themselves. Most other stents have steep performance drops after 360 days. With Supera®, the consistent results at 1 and 2 years really make me confident that I am providing my patients with the best solution for treating the SFA. I'm looking forward to helping more physicians gain comfort with the Supera® vascular mimetic implant when they come visit me in Louisiana!

For more information, please contact your Abbott Vascular representative. For important safety information, please see page 43 of the article PDF.

  1. Data on file at Abbott Vascular.
  2. Arena FJ, Arena FA. Intravascular ultrasound evaluation of interwoven nitinol stents at implant. J Vasc Med Surg. 2013:1:116. © 2013 Arena FJ, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
  3. Supera® Peripheral Stent System instructions for use. Data on file at Abbott Vascular.
  4. Garcia LA. Final 12-month outcomes from the SUPERB trial using the Supera woven nitinol stent. Presented at: Transcatheter Cardiovascular Therapeutics; October 22, 2012; Miami, FL.
  5. Scheinert D, Grummt L, Piorkowski M, et al. A novel self-expanding interwoven nitinol stent for complex femoropopliteal lesions: 24-month results of the SUPERA SFA registry. J Endovasc Ther. 2011;18:745-752.
  6. Scheinert D, Werner M, Scheinert S, et al. Treatment of complex atherosclerotic popliteal artery disease with a new self-expanding interwoven nitinol stent: 12-month results of the Leipzig SUPERA popliteal artery stent registry. J Am Coll Cardiol Intv. 2013;6:65-71.
  7. Clinical data on file at Abbott Vascular.
  8. Scheinert D. SUPERA-500: Long-term follow-up of interwoven nitinol stents for treatment of femoral and popliteal arteries. Presented at: Leipzig Interventional Course; January 23, 2013; Leipzig, Germany.
  9. Goverde P. Experience with high radial force interwoven nitinol stents in femoro-popliteal arteries—results of the AURORAA-registry. Presented at: Leipzig Interventional Course; January 25, 2013; Leipzig, Germany.
  10. Molenaar A. Outcome of interwoven self-expanding nitinol stents for long complex SFA lesions. Presented at: Leipzig Interventional Course; January 26, 2012; Leipzig, Germany.
  11. Goltz JP, Ritter CO, Kellersmann R, et al. Endovascular treatment of popliteal artery segments P1 and P2 in patients with critical limb ischemia: initial experience using a helical nitinol stent with increased radial force. J Endovasc Ther. 2012;19:450-456.
  12. Chan YC. Primary stenting of femoropopliteal atherosclerotic lesions using new helical interwoven nitinol stents. Presented at: Leipzig International Course Asia-Pacific Meeting 2013; March 2013; Hong Kong.
  13. Pacanowski J. Real world experience with interwoven nitinol stents in complex femoro-popliteal lesions. Presented at: Leipzig Interventional Course; January 24, 2013; Leipzig, Germany.
  14. Kovach R. SAKE study: SUPERA interwoven nitinol stent outcomes in above knee interventions—12 months results. Presented at: Leipzig Interventional Course; January 24, 2013; Leipzig, Germany.