IAGS Proceedings - <br />
Troubling Lesion Subsets: Bifurcation Disease

Moderator: Kirk Garratt Panel Members: Tom Linnemeier, Brian O’Murchu, Jeffrey Werner Tom Linnemeier: The best treatment option today for a true LAD diagonal bifurcation lesion is to place a stent in the LAD and dilate through the sidebranch. How many people have performed directional coronary atherectomy in the past year? How about in the last month? There are practitioners who are still adept at the technique, but I am not one of them. The Japanese, on the other hand, frequently use directional coronary atherectomy to treat bifurcation lesions — sometimes with stenting. At the Washington Hospital Center, I saw Gus Pichard perform a beautiful directional atherectomy procedure with a Flexicut on an LAD diagonal bifurcation. I also saw a rotational atherectomy procedure performed in North Carolina on an LAD diagonal bifurcation. In my view, Dr. Cowley’s last slide makes a big statement: bifurcation stenting with currently available stents is probably not an appropriate treatment unless it is absolutely necessary. I treated a relatively simple multi-vessel, right circumflex, diabetic patient about a month ago at Stanford. Why didn’t I send this patient for bypass surgery? Because I am an interventional cardiologist and I believe it is my job to avoid bypass surgery when possible. I placed two stents in the LAD and the diagonal started to close, thus endangering the patient. I tried unsuccessfully to balloon it and resorted to placing a bifurcation stent in order to prevent an acute complication with the idea that if it restenosed, there would still be the option of CABG later on. CABG is certainly a treatment option for an LAD diagonal bifurcation lesion, but from a percutaneous standpoint, I think the best treatment option today is to stent the parent vessel and dilate through the stent strut with a stent, although not every stent will allow you to get the size you want through the bifurcation. Otherwise, if you are still adept at directional coronary atherectomy, and if it is a case involving a relatively small calcified vessel, I think rotational atherectomy is an appropriate treatment choice. Jeff Werner: I would like to show you these slides of a case involving inadvertent stenting of a bifurcation lesion. The actual question is: Does radiation treat both limbs? (This is a good question for Dr. Bonan.) The case involves a patient who was 48 years old when he came to our hospital with an acute anterior wall myocardial infarction and a stub for a LAD. One of my colleagues performed emergency angioplasty on him. Once the vessel was opened, my colleague saw that there were bifurcations — a big LAD and a diagonal — and he wasn’t quite sure how to proceed. He thought that the diagonal was larger than the LAD so he just shoved a Palmaz-Schatz stent through the diagonal, across the LAD. The patient was then stable. I was a bit concerned when I looked at the image and saw that my colleague had basically crossed half of the LAD. Nevertheless, the patient was fine and experienced absolutely no symptoms until five years later when he began to have chest pain. A treadmill test revealed anterior changes. The thallium test showed a clear-cut reversible defect on the anterior wall, with distribution more on the LAD than on the diagonal. We decided to intervene on this patient. The origin of the LAD has a very high-grade stenosis — through the struts of the stent, actually. I attempted to treat the patient medically because, after all, he had gone five years symptom-free. I told the patient that I could try to dilate through the lesion, but I thought the restenosis rate would be fairly high. I also presented surgery as another option. The patient asked about rotational atherectomy which I told him was feasible, but might also result in a fairly high restenosis rate. When the patient asked about radiation treatment, I told him I wasn’t quite sure what exactly I would radiate. After some thought, however, I determined that perhaps I could dilate the LAD and radiate the lesion — because the restenosis rate would be expected to be relatively high, and I wasn’t sure what it would do to the diagonal which did not look very diseased. I spoke with Paul Teirstein about this case and about my concern that I wouldn’t be able to get the device back out through the side of the stent. Dr. Teirstein assured me (as he always does!) that there would be no difficulty in doing this, so that’s the approach I decided to take. Besides, the patient, who is only 53 years old, really wanted to undergo this procedure. To reiterate the patient’s situation: there is one Palmaz-Schatz stent which goes into the diagonal and the LAD comes through the side strut of the Palmaz-Schatz stent. The patient was already on Plavix, aspirin and Norvasc — virtually everything. I placed a 2.5 mm balloon through the side of the stent and dilated it, trying to open the strut slightly. I did it twice, actually, taking it up to fairly high pressure the second time to try to get the notch out of the balloon which I was not able to do entirely. I was mainly trying to give myself a way to get the device through. Interestingly, five years later, there is still plaque shift — possibly thrombus — at the origin of the diagonal, although I gave the patient Integrilin. Raoul Bonan: What about the lesion in the diagonal? Jeff Werner: There is either a clot there or we have shifted some plaque over. Remember, this is now five years after the patient’s initial procedure. It didn’t look too bad, but I do think there was something going on in the diagonal. I don’t recall the exact dwell time, but it was probably about 15 minutes. My question for Dr. Bonan is: Are we radiating the origin of this? I radiated only the LAD, but how much radiation do you think the origin of the diagonal is receiving? Raoul Bonan: Not much. Jeff Werner: We radiated this and took some pictures. The patient received some intracoronary nitroglycerin. The LAD looks quite good, but there definitely still appears to be a problem in the diagonal. Blood flow was good after administering the intracoronary nitroglycerin. At this point, however, I was not exactly sure what to do; I didn’t want to be overly aggressive. There was definitely something there in the diagonal and I hoped that when I went back to look at the pictures, it wouldn’t look like much of anything. There was something there, however, so I rewired it, went across, and redilated the lesion with just a balloon; I did not place a stent. The result was not perfect, but I called it “good” as we say, and decided to “beat it” at that point. Tom Linnemeier: You are certainly not through the articulation of the Palmaz-Schatz stent. Jeff Werner: My first question is: What else would you have tried besides the kissing balloon? And my question for Raoul is: Did we radiate the diagonal in this case? Raoul Bonan: I think yes. I performed a procedure on a 55-year-old woman at a Montreal Heart Institute live course one year ago. She had a lesion on the proximal LAD and Cx. Then she ended up having two previous PTCAs and the mammary graft on the LAD was gone. She came to see us with a stent in the proximal portion of the LAD and the Cx the first position of the radiation in one vessel, second position of the radiation in the second vessel. I refused to treat the first marginal because it was a threat for the left main. I told the patient she will be fine for now and should take medication. I told her she should wait one or two years, then I would do something with the marginal in case of symptoms. With radiation, my understanding is that in the overlap, there is a low risk of overdosing due to the size of the bifurcation. Michael Cowley: How many cases have you performed? Raoul Bonan: We currently have five completely documented cases with no problem at 6-month follow-up. Chris Cates: We have experienced similar problems and have attempted to find a solution. My colleagues and I have come to a consensus about the need to do rotational atherectomy through the sidewall of these stents and then post-treat with radiation, which is a sort of amalgam of debulking and freezing the result. I would like to know if others have employed this method of rotational atherectomy followed by radiation. Thus far, we have treated ten patients at our center — not many, but at least it’s a start. It would be helpful to compile data and publish a composite result of clinical experience for these patient subsets in which the volume is small, but the problems are significant. Perhaps the IAGS could spearhead this type of data collection in the future and have the findings published in the Journal of Invasive Cardiology. Tom Linnemeier: A couple of years ago at an annual Fellow’s course which Gregg Stone and I organize each spring, we performed rotational atherectomy on a patient with in-stent restenosis. At the time, it was very controversial because we didn’t know if we were going to send metal shavings downstream. We discussed the situation for at least twenty minutes before actually performing the procedure, considering the possibility that the device might get stuck or that sparks would fly. The bottom line, however, is that it worked beautifully. In fact, we published the results as a case report. I like the idea of using the Journal of Invasive Cardiology as a forum for discussing these types of cases and problems. For instance, if each of us treats four or five patients in these special subsets and the data are then compiled in a registry, we could gather a substantial amount of valuable information in a short period of time. Jeff Werner: I think it depends on what you think the biology of in-stent restenosis is. I used to perform rotational atherectomy on in-stent restenosis patients, but I don’t anymore, partly because I think the restenosis rate without radiation is fairly high. Also, the only reason to do rotational atherectomy, in my opinion, is if there is trouble with a balloon. If you use a smaller balloon because it goes squirting out of each side, particularly with radiation, you can try to open the vessel enough and IVUS it to make sure that the stent was not initially underdeployed. You would then deploy a larger stent and treat the lesion with radiation. I have found that following these steps takes care of the problem. By the way, this is not a piece of calcium or anything, just fibrous tissue. I may be wrong about this, but I have found that if I just use a balloon that is slightly longer and a half-size smaller than the vessel, I don’t have quite as much trouble with it squirting back and forth; I can dilate the vessel and then radiate it. Chris Cates: Can you really know for certain that you have moved that strut out of the middle of the bifurcation with a balloon? With the Rotablator device, I wonder whether you actually do selectively cut through the piece of metal. Paul Teirstein mentioned that Boston Scientific has looked at this issue, so perhaps he would like to comment on it. It seems to me that we have been less than happy with our results using a balloon alone for that reason. In fact, I have tried to IVUS a few of these lesions and found that the IVUS catheter got stuck, which was very disappointing. Tom Linnemeier: Actually, the problem you encountered in the diagonal may have been because you deformed the Palmaz-Schatz stent on the other side of the vessel, something that could have been remedied by applying the Rotablator to it. Have you ever encountered that? Chris Cates: I probably have but just didn’t notice it. We have had devices get stuck, particularly balloons, where the balloon is sheared off and half of it is stuck in the diagonal. Tom Linnemeier: That is one of the reasons I agree with Jim that the kissing balloon ought to be used on a bifurcation lesion. Howard Cohen: Another option that we use for large vessels — and we want various options for our patients depending on their anatomy — is a hybrid technique of a mid-CAB and angioplasty and stenting of the diagonal. The results using this hybrid technique have been quite good. What I like about it is that there is probably no better revascularization than the LIMA to the LAD because we know that it confers longevity to the patient. Angioplasty of the diagonal, once the LIMA is in place, is a “slam dunk” that requires only ten minutes to complete, whereas a case like the one Jeff mentioned requires more time. With an experienced surgeon who is adept at mid-CABs, the patient can go from the operating room to the cath lab in a short period of time. Also, patients are very accepting of the proposition of treating the LAD through a mid-CAB procedure. Another advantage is that I will live a little longer by not having to spend so much time in the cath lab fighting with these bifurcation lesions! This hybrid technique is a reasonable approach for the right patient. I am not saying it’s appropriate for every patient because, obviously, if the vessel is small, the diagonal is probably not worth it. On the other hand, in the case of a large vessel with complex disease, I find the hybrid technique quite effective. Alfredo Rodriguez: I have a question for Raoul Bonan. Are you not concerned about damage in the left main and about late thrombosis? Raoul Bonan: Late thrombosis is really a problem of the past now that Plavix is available. The incidence of late thrombosis with Plavix over more than a one-year period is less than 1%; it really is no longer an issue. Since 1998, the 7% late thrombosis rate has fallen as Plavix use has increased. Paul LaViolette: I would like to answer the mechanical question about the Rotablator device which has been studied extensively since its application in cases of in-stent restenosis with varying degrees of success. There is no question that the Rotablator will ablate the stent strut. Thus, if the goal is to mechanically eliminate an obstruction to a branch vessel, the Rotablator will accomplish that. There is also no question that small metal shards are generated during ablation, however we have not yet determined the nature of those embolic particles. But there is no question that the Rotablator eliminates the stent strut. Howard Cohen: It offers local drug delivery of iron! Raoul Bonan: To ablate the metal, you need a lot of injury, a lot of heat, and I don’t know if that will provoke more healing. Hall Whitworth: I have a question regarding the selection of the type of radiation for a bifurcation lesion. I am under the impression that gamma radiation may be more effective than beta radiation in achieving deeper penetration because of beta’s dose drop-off rate. In the case Jeff discussed, will the gamma radiation applied at the turn in the bifurcation perhaps have greater effect on the ostium than beta radiation due to the dose drop-off? Jeff Werner: I didn’t know how much penetration would be achieved, but theoretically, the photon exposure and the distance are longer with gamma radiation. I thought it might provide some radiation to the ostium and the diagonal. However, with the Novoste beta system, the gamma radiation would probably have traveled about 3 or 4 mm from the catheter, which was probably close enough for the bifurcation lesion. On the other hand, beta radiation is hotter, so it’s sort of a toss-up. The other factor I took into consideration was the catheter. Raoul can probably tell us if the catheters are smaller, but I was a bit nervous about using a Novoste catheter, which is a little larger; the Cordis gamma catheter is smaller in diameter. My biggest concern was the possibility of getting the radiation catheter back, which would obviously have been horrendous. Thus, I wanted to use the lowest profile, simplest device available. Raoul Bonan: The prescribed dose is a certain amount at a certain distance for both beta and gamma radiation. The only difference between the two is that beta’s dose drop-off is rapid. When, for example, you decide to prescribe 20 gray at 2 mm, there is almost nothing at 4 mm on the beta radiation device, but on the gamma device, there will still probably be 40 or 50% of that amount. In terms of overlap, the non-target tissue receives less radiation than the target tissue, which receives the prescribed dose. If you prescribe 20 gray to the target tissue, it receives that amount when either beta or gamma radiation are used. Jeff Werner: That’s what I was hoping — that there would be less drop-off and thus greater penetration, possibly at the origin of the diagonal. Also, in this particular case, I liked the smaller catheter because of its pull-back capability. Raoul Bonan: Will the self-expanding stent be more effective in bifurcation lesions? There is some discussion about self-expanding stents taking better care of the proximal portion of the lesion. Where are you with this, Tom? Do you have any new ideas about the mechanical aspects of stents for bifurcation lesions? Tom Linnemeier: In the next three months or so, Guidant will be launching an in-house project on a sidebranch access stent. Actually, it is not really a sidebranch or bifurcation stent so much as it is an ostial protection stent, designed to protect the ostium using two different balloon catheters. In fact, I think that most of the data Michael presented on bifurcation stenting were not very good. What I really care about is whether we can protect the ostium and prevent an acute complication and then be able to place a stent if needed. With regard to self-expanding stents, I don’t know the answer. Jim Zidar: The most difficult aspect of using self-expanding stents for bifurcation lesions is that the stent placement must be precise. The stent has a sleeve retrieval system but there is currently no system that comes on one tube. A company which I believe is called Devex has developed a system in which the device is self-expanding on one side. This company claims that the device can be accurately deployed in a normal bifurcation lesion in the SFA profunda of a pig. Whether this can be done in a plaque-laden LAD is another question, however. I agree that a self-expanding nitinol stent in a bifurcation lesion might be effective. Making it a reality, however, will be a challenge. Max Amor: Self-expanding stents for bifurcation lesions have been applied in the iliac and the common femoral arteries, but in the periphery, there are two ways to approach the problem: 1) contralaterally, or 2) directly. Thus, the stent can be deployed from the proximal to the distal end or from the distal to the proximal end. However, in the heart, two guidewires must be placed, one in the LAD and one in the diagonal. The stent must be deployed in the diagonal and the LAD together. Also, the proximal end may not be at exactly the same level, which makes the procedure technically very difficult. Self-expanding stents are therefore very effective in treating bifurcation lesions in the periphery, but there is only one way to access these lesions in the heart. Tom Linnemeier: Did you get any grief from your radiation oncologist for doing this procedure since this is not really a case of in-stent restenosis? Is your indication for gamma radiation specifically for in-stent restenosis? Jeff Werner: The radiation oncologist is actually in favor of our performing this procedure. He is quite an aggressive practitioner and thought that if there was any chance it would work, we should try it.