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SFA Roundtable In what circumstances is percutaneous transluminal angioplasty (PTA) alone the treatment of choice? Dr. Ohki: I'd say TASC A, short, focal stenotic lesions. One should start off with angioplasty alone, and the results of PTA alone in these circumstances are as good as those with stenting or anything else, and it doesn't leave behind a foreign body like a stent. You can also repeat it multiple times, and it doesn't hamper future surgery. The cost issue also comes into play. If you put all this together, I think PTA should be the gold standard for such short focal lesions. Dr. Laird: I agree with Dr. Ohki. Focal lesions less than 4 cm in length generally respond well to balloon angioplasty, and we can expect, based on historical literature, that the patency rate at 2 to 3 years is probably going to be in the 70% to 75% range for very focal lesions. When you get beyond 4 cm, in the range of 4 cm to 15 cm, recent studies would suggest that the results are going to be better with stents. In particular, the ABSOLUTE trial showed lower restenosis at 6 months by angiography and 9 months by duplex with the Absolute stent (Abbott Vascular, Abbott Park, IL) compared to balloon angioplasty. Short, focal, de novo lesions without extensive calcification would be probably the primary place for balloon angioplasty in the modern era. Dr. Rundback: I think angioplasty alone is ideal for patients who fulfill the perfect criteria: focal lesions, certainly less than 3 cm and possibly less than 5 cm to 7 cm, without much calcification, concentric lesions, good inflow, and unimpaired outflow. Those patients should generally do well with angioplasty alone. Dr. Ohki: Some people might also argue for FoxHollow atherectomy (Redwood City, CA) because that technology does work very well under these circumstances, but I think it is tough to beat balloon angioplasty. It is simple, quick, safe, and cheap. To make that treatment into an atherectomy procedure, which has the potential of distal embolization, would not be cost-efficient considering the need for filters and the cost of the device itself (approximately $3,000). Although the result might be good with atherectomy, I think it might be difficult to justify. Dr. Laird: I agree. I think in the absence of randomized data it would be difficult to justify the added expense of excisional atherectomy for focal disease, but maybe it is viable for longer, more complex disease. The other question is whether the various specialty balloons such as PolarCath (cryoplasty) or the Cutting Balloon (Boston Scientific Corporation, Natick, MA) improve upon the results with balloon angioplasty for focal disease; we don't have the answer to that yet either, and it is difficult to justify the added expense of these specialty balloons for such focal disease. Dr. Ohki: In the era of evidence-based medicine this anecdotal case may not have any role, but I had a 45-year-old female patient who had a 3-cm stenosis with severe claudication. I performed balloon angioplasty 8 years ago, and she came back to see me recently. She still has a dorsalis pedis pulse, widely patent SFA, and absence of claudication symptoms. Cases like this one show the beauty of stand-alone angioplasty; it will difficult for any stent or atherectomy device to perform better than this. In which cases should stents be used in the treatment of SFA disease? Dr. Rundback: Clearly, stents should be used for patients who have a suboptimal result for angioplasty with residual flow-limiting dissection and/or residual stenosis, or just sluggish flow after angioplasty. Also, in long, complex stenoses and occlusions, stents will likely be necessary. I am increasingly of the opinion that for all the subintimal recanalizations, stents are needed, although it is not entirely clear if you need to stent the entire tract or just the re-entry point. Dr. Laird: The recent literature would suggest that stents are superior to balloon angioplasty for moderate-length and moderate-complexity SFA disease. The RESILIENT trial and the ABSOLUTE trial included lesions up to approximately 15 cm in length, and in those two trials, the results appear superior with stenting. We have only preliminary 6-month data from RESILIENT, which suggest better patency at 6 months with stents, but the 9-month data from ABSOLUTE trial also showed superiority of stents. I think it is important to note, however, that these are 9-month to 1-year data; as Dr. Ohki mentioned previously, we don't really know the longer-term outcomes with stents. We might find that the restenotic process continues over time. It is possible that by 3 to 5 years, patency will have diminished significantly with stents. Dr. Ohki: The FAST trial compared the Luminexx stent (C.R. Bard, Inc., Murray Hill, NJ) to angioplasty alone in a randomized fashion. They showed a statistically significant advantage of stents over angioplasty up to 6 months, but when the 12-month data were presented at TCT 2006, they showed a significant catch-up phenomenon in the stenting arm, and there was no statistical difference between the two groups in terms of Duplex-based restenosis rate. So, we are already seeing this catch-up phenomenon in one particular study and we should be careful not to draw conclusions prematurely based on 6-month or 9-month data. Even if 12-month data hold statistical significance, patients do live longer than 12 months, so I think we should be careful about that. Dr. Laird: I think that study may be a bit of an outlier, though, because it involved the use of a stent that has been associated with a higher rate of stent fractures and complications associated with stent fracture, so we have to be cautious about drawing any major conclusions from the FAST trial data. Dr. Ohki: I agree, and I believe the results with the S.M.A.R.T. stent (Cordis Corporation, a Johnson & Johnson company, Miami, FL), the LifeStent (Edwards Lifesciences LLC, Irvine, CA), and the Absolute stent are better. I do think one needs to be aware of what stent is used because, after all, not all stents are created equally. Are there significant differences between the currently available stents, which, albeit, are not indicated for use in the SFA? Dr. Ohki: I think there are significant differences. Some people might say that all nitinol stents are equal, but I certainly disagree with that. Some of the different characteristics include the available length; some stents only come in lengths up to 8 cm, whereas the longer stents, such as the ev3 stents (Plymouth, MN), are available in 15 cm. Most of these SFA lesions are very long, and length is a pretty important factor when I choose a stent. The fracture resistance is quite different, which has been suggested in the FESTO Trial, and this relates to how well the electric polishing of the surface has been done. The Luminexx stents that were tested in FESTO did not have any electric surface polishing, whereas the other stents did. Radial force is the least of my concerns because most of the SFA lesions respond well to angioplasty, and the main reason I use a stent is to tack down a dissection, not necessarily to fight acute recoil. Lesion coverage is an obvious factor, but I personally do not think there is too much difference in any of these closed-cell or open-cell designs. However, if you're comparing a coil stent versus a nitinol slotted tube stent, there is a tremendous difference in lesion coverage, which I do consider a significant factor. The deployment mechanisms are easier and a little more accurate in some than others, but all in all, I think they all perform well in this regard. Some stents have radiopaque markers, and clearly these are easier to use. Dr. Laird: I agree with the factors that Dr. Ohki mentioned, I think the differences are fairly subtle in terms of the design and capabilities of these stents. There may be some advantages to the more fracture-resistant designs, such as perhaps, the Edwards LifeStent or the ev3 Protégé Everflex Stent, but that remains to be proven. In regard to Dr. Ohki's comments about the delivery systems, I think they are all fairly equivalent today, although there may be some advantage to those devices that have the stabilizing sheath, which makes it a little bit easier to deploy the stent without it moving forward during the release process. Dr. Rundback: Aside from those mentioned by Drs. Ohki and Laird, there are just a few other differences of the stents that we currently use. As of this moment, the only stent that is available in long lengths with a 6-F platform is the ev3 Everflex, which comes in sizes up to 15 cm in length. Another device that stands out is the Abbott (Santa Clara, CA) line of low-profile Expert stents. They go through 4-F or 5-F sheaths, and they have a very thin metal strut surface and, therefore, they are well suited for smaller arteries and tibial arteries. Having said that, in the peripheral vasculature, all the rest of the stents generally provide reasonably good scaffolding, but those are the ones that have differentiating features. Regarding stent fracture, certainly, if given my choice between having a nonfracturable stent or a fracturable stent, I would choose fracture resistance. That being said, it is probably only the more severe levels of fracture with complete strut separation that will be associated with clinical problems. Obviously, there are tremendous flexion forces, point compression, torsion, and motion in femoral stents, so I would imagine that there would be mechanical stress fatigue in all stents over time. The thing is, we are dealing with our elderly population, who may not have as much mobility and movement of the leg, so it may be possible to make a stent that, for clinical purposes in this population at least, is essentially fracture resistant. When should laser atherectomy be used as therapy for SFA disease? Dr. Rundback: Initial efforts with lasers did not bear fruit, in that they were not effective in the intermediate and long term. However, I have seen real interest lately in laser as an adjunctive tool for debulking. I like the idea of using laser in long-segment femoral occlusive disease to debulk, either as a stand-alone therapy or to clear room for placement of a stent. Personally, I would lean toward the latter strategy—create a good-flow lumen by debulking with the laser, and then stent areas of residual disease. Dr. Laird: I believe that laser has a role to play in the SFA, particularly for the more complex lesion subsets—the long occlusions or the more diffusely diseased vessels. The role of laser is to allow us to get better angiographic results without the need for stents. In particular, stents do not perform as well in the SFA when we use lengths of 20 cm to 30 cm to treat the entire diseased vessel. Laser also is very effective for debulking thrombus, so it can be used in thrombotic lesions, or patients who present with more acute or subacute symptoms. It can also be very useful for the treatment of in-stent restenosis, in which it allows us to get a better angiographic result with laser followed by balloon angioplasty. Laser does have a role to play, but there is no definitive evidence showing that for all comers, laser results in a reduced restenosis or better long-term patency than standard angioplasty or stent techniques. When should directional or excisional atherectomy be used? Dr. Ohki: When we talk about excisional atherectomy today, we are primarily discussing the FoxHollow SilverHawk, although there are other atherectomy catheters like the Pathway (Pathway Medical Technologies Inc., Redmond, WA) and the CSI device (Cardiovascular Systems Inc., St. Paul, MN) on the horizon. I think the SilverHawk is a great device. The primary advantage is that it does not leave behind any foreign body. I have had a number of patients come back with in-stent restenosis, and excisional atherectomy works well in this setting as well, although once in a while, the blade gets caught on the stent strut. Whenever I deal with in-stent restenosis, the pre-existing stent always gets in the way of any other effective treatment. One way to address it is to put another stent or a covered stent, but sooner or later, you run out of real estate in the vessel. With atherectomy, you leave nothing behind, so hypothetically, you can repeat this as many times as you want. In fact, when I perform atherectomy, I tell the patient, "This is a device that will work for at least 1 or 2 years, but you may have to come back so we can clean it out again." I say that up front, and if they do unfortunately come back, because they have been informed of the possibility beforehand, my patients are not upset. After all, most if not all endovascular therapy for the lower-extremity is palliative rather than curative. Dr. Laird: It is also important to remind people that neither the SilverHawk nor the laser is approved by the FDA for in-stent restenosis, so we are talking about an off-label use. I like to use excisional atherectomy for areas in which I don't want to place a stent, such as in the common femoral or popliteal artery, and also for ostial disease of the SFA or perhaps the profunda femoris. It can be very effective in those situations. Excisional atherectomy can also be used for complex SFA disease. What we really don't know, because we don't have enough data, is how much more effective debulking with excisional atherectomy is compared to just doing angioplasty for lesions in the SFA. We need better studies. Dr. Rundback: I agree that there are some instances in which directional atherectomy is a first-line therapy. In patients with very eccentric lesions, directional control is especially useful. Also, individuals who have recurrence due to fibrointimal hyperplasia—particularly in-stent restenosis—are treated very well with directional atherectomy. Apart from those cases, however, the role of directional atherectomy remains to be determined. The TALON registry has shown some favorable results, but that is only an observational, noncontrolled study. I would venture to say that atherectomy is not going to sustain particularly well as single therapy in the majority of long segment cases, but I could be wrong. Dr. Laird: If you believe in the TALON data, their investigators have treated fairly diffuse, long TASC C and D lesions, and if you believe in "clinical patency" as a result, the data appear to be fairly significantly better than balloon angioplasty alone in those fairly challenging cases. The big question is if you believe in the data. As Dr. Rundback pointed out, it is not comparative by design, and the data collection methods were somewhat suspect. But, I think regardless of how you feel about TALON, there may be a role for the technology in challenging lesion subsets, with the hope that you can avoid placing a stent in the artery for avoidance of issues related to late restenosis and stent fracture. Dr. Ohki: I agree that there are no data to compare the long-term performance between balloon angioplasty alone and atherectomy, but my gut feeling is that in TASC B and C lesions, atherectomy does perform better than angioplasty alone. I think it is probably better than angioplasty alone for short, complex lesions also. How important are the devices that are designed to cross subintimal channels in the treatment of SFA disease? Dr. Ohki: These devices are of utmost importance. I cannot live without them. If I am dealing with short, focal stenotic lesions, obviously there is no role for it; a guidewire, such as the Terumo Glidewire (Terumo Medical Corporation, Somerset, NJ) would suffice. But for a CTO lesion, I think it is almost malpractice nowadays to attempt treatment in the absence of a Frontrunner (Cordis Corporation), Outback (Cordis Corporation), or Pioneer catheter (Medtronic Vascular, Santa Clara, CA)—any one of the three. The benefits are that, first, it shortens the procedure time, but more importantly, it does not iatrogenically make the lesion longer. One can always cross the lesion with a guidewire and a catheter, there's no question about that. I could start off at the SFA, and if the runoff vessel is at the adductor canal in the distal SFA, I might re-enter with the guidewire right at that point, or at the knee, or below or in the tibial vessels. But if you re-enter the true lumen below the knee, then you have iatrogenically or artificially prolonged the lesion, and the patency rate will go down if the lesion gets longer. More importantly, the future bailout procedure, including surgical procedures, will be much more difficult if the lesion is lengthened. Above-the-knee femoropopliteal bypass does much better than its below-the-knee counterpart, which means that if you convert an above-the-knee bypass into a below-the-knee bypass, you are doing a patient a disservice. The benefit of these crossing devices is that they allow you to make the lesion as short as possible, leading to better possible patency rate, a reduced number of stents if you are stenting, and all of the future surgery options remain widely open. Dr. Rundback: These devices are excellent tools in treating SFA disease for limb salvage. Clearly, they greatly facilitate subintimal recanalization of chronic total occlusions, and the available devices are essentially equally effective, at least in my experience. The reason I make the differentiation regarding subintimal recanalization in the treatment of critical limb ischemia compared to claudication is that the data suggest a high clinical failure rate when treating claudication, and that bypass surgery is probably better in good operative candidates. However, in patients who have critical limb ischemia, where you only need to achieve sufficient perfusion for wound healing or complete relief of symptoms, subintimal recanalization is an extraordinary important and effective strategy associated with high rates of limb salvage. Dr. Laird: I find the re-entry devices to be particularly useful. The primary reason for failure when performing intervention on the occluded SFA is subintimal trapping of the guidewire. With the help of the Pioneer or Outback catheter, re-entry into the true lumen can be achieved in almost 100% of cases. While the technique of deliberate subintimal recanalization (Bolia technique) can be effective, one cannot always control the point of re-entry very well. As Dr. Ohki mentioned, extension of a dissection into the popliteal artery can occur and potentially complicate future fem-pop bypass procedures. With the re-entry devices, the point of re-entry into the true lumen can be controlled and one can avoid extending the segment that needs to be stented. Dr. Ohki: In terms of the Frontrunner versus the Pioneer and Outback, the Frontrunner recannalizes the true lumen, whereas the other two go into the subintimal plane and come back out. I think there is an important difference here because if one is planning to use a FoxHollow atherectomy-type device, it would be necessary to use the Frontrunner and maintain the true lumen. However, if the plan is to place a stent, in my mind, it doesn't matter where the wire or the device crosses. If you are in the subintimal space and then come back in with the Outback or Pioneer, that subintimal space is not ideal for atherectomy because you do not want to do an atherectomy on a thin-wall adventitia. For that reason, I think atherectomy plus the Frontrunner is a good combination, and stenting can be done with any of the three available devices. What is the ideal armamentarium for treating long (>15 cm) SFA lesions? Dr. Ohki: In terms of currently available devices, ideally, I would start with one of the devices designed specifically to cross the lesion. If you remain in the true lumen, then atherectomy will be the ideal; if you go in subintimal, then I would use a stent, but stenting should be performed with as few stents as possible, by using as long a stent as possible. In other words, putting in two 8-cm stents is inferior to one 15-cm stent. Use of protection devices should be encouraged if there is any possibility of loose material, especially in the setting of poor runoff. In the future, I think the recanalization tools will not need to change much. I am sure we can make them better, but the technical success rate of crossing a CTO lesion has become almost 100% using these devices, so we are close to the ideal. How we maintain patency is the big issue that has to be solved through future device innovation. One possible solution is biodegradable or bioabsorbable stents that maintain the lumen during the acute phase, deliver a drug, and then disappear when the vessel has healed. I think that would probably be the ideal strategy or tool, but I am just not convinced that it is going to be possible. Anything biodegradable has less radial force, and is also more likely to invite inflammation, and inflammation is associated with recurrent intimal hyperplasia. It will be very difficult to find a material that would get absorbed but does not cause inflammation. But short of that, I think a biodegradable, drug-coated stent would be probably the ideal. Dr. Rundback: We have adopted what we call a "phased revascularization" approach. That is, if we can cross in the true lumen plane, then we will start with angioplasty or cryoplasty and/or atherectomy, depending upon the lesion characteristics, and determine if further treatment is necessary. The goal is to be cost-efficient and therapy-efficient, because we may be able to avoid stenting in the initial treatment. That being said, we are fairly liberal with stenting as a second phase of revascularization for patients whose initial therapy is suboptimal, and stent grafts for complex stent failures or recurrences. The Hemobahn device (Gore & Associates, Flagstaff, AZ) has actually shown extraordinarily high patency, particularly if you dilate the graft more than 5 mm to 6 mm. However, these are very expensive devices, and there is a high risk of embolization and a larger introducer device, so there can be more femoral complications. There is also a small and transient, but still present, inflammatory reaction related to placing stent grafts. I think that if a company were to develop a low-profile, long-segment, stent graft that is relatively inexpensive, it would probably become a market-leading device. Dr. Laird: I don't think we know what the right answer is for these longer lesions. I like Dr. Rundback's approach of phased revascularization. This is similar to my approach. I don't think the best solution is to start out by lining the entire SFA with stents. There are certainly those cases when this may be the only way to get a satisfactory acute result, but as a general rule, I try to avoid this. If stents are to be used, I would favor the use of the longer (fracture resistant) stents rather than multiple, shorter stents. The approach of treating longer occlusions with Viabahn stent grafts is an interesting (albeit expensive) strategy. I look forward to the results of the VIBRANT trial to give us additional information regarding the benefits of stent grafts versus bare metal stents in the SFA. What should every intervention lab have in their inventory for the endovascular management of SFA disease? Dr. Rundback: First of all, you need puncture needles, but you don't just need 19-gauge needles, you also need micropuncture needles because these arteries are often calcified and difficult to enter. Obviously, you need a whole assortment of catheters and sheaths. We tend to use braided crossover sheaths, such as the Raabe or the Ansel sheaths (Cook Incorporated, Indianapolis, IN), particularly for working from one side to the other. These tend to really facilitate the subsequent intervention and they have a very short lead tapered tip on the introducer, which allows easier and less traumatic insertion. Both .014-inch and .018-inch crossing and support wires must be available, and we use a lot of hydrophilic catheters and a whole range of small-vessel and intermediate-vessel balloons, stents, and grafts. Self-expanding stent grafts should be available, if for no other reason than the rare cases in which there is vessel rupture and you need to seal the defect. Dr. Ohki: The Terumo Glidewire and several directional catheters are a must. I would also suggest the Frontrunner and a re-entry device such as the Outback or Pioneer. A .014-inch support wire, a distal filter, and .014-inch and .035-inch–compatible balloons, preferably long ones (8 cm), are helpful. Long stents are necessary, like the 15-cm Protégé, which is by far the longest. Also, the S.M.A.R.T. stent has good data, and I have a lot of trust in it. The ideal filter is Spider filter (ev3), because you can deploy the filter over the same wire you use to cross the lesion, and the ev3 filter is the only device to offer this capability. I also cannot live without the FoxHollow device for the reasons mentioned previously. Dr. Laird: It is critically important to have a full complement of long balloons and long nitinol stents. As has already been discussed, having one or both of the re-entry devices in stock (Pioneer, Outback) is important. There are pros and cons to each. I also think the debulking devices (excimer laser, excisional atherectomy) are useful for complex lesion subsets and a necessary addition to the armamentarium. One always needs to be prepared to deal with complications and so a full inventory of bailout equipment is desirable. Catheters for thromboaspiration, AngioJet (Possis Medical, Inc., Minneapolis, MN), covered stents, thrombolytics, and so forth, should be readily available. John R. Laird, Jr, MD, is Medical Director, UC Davis Vascular Center, in Davis, California. He has disclosed that he is a consultant to Spectranetics, and an advisory board member for Edwards, Cordis, Boston Scientific, Medtronic, and ev3. Dr. Laird may be reached at (916) 734-2029; john.laird@ucdmc.ucdavis.edu. |
