The Bifurcation Stent

Case study. A 73-year-old female with no previous cardiac history presented with a history of crescendo chest pain over the last six weeks. Her symptoms were relieved by rest and nitroglycerin. Her risk factors included type-2 diabetes mellitus, hypertension, obesity, and a family history of premature coronary artery disease. Physicalexamination was unremarkable, and cardiac markers were negative for myocardial necrosis. Cardiac catheterization was performed at the referring institution. The presence of a bifurcating 75-95% lesion involving the mid left anterior descending artery (LAD) and the ostium of a large second diagonal branch (D2) was noted (Figure 1). There were no other significant lesions in the coronary tree, and left ventricular function was within normal limits. Given the presence of progressive symptoms and a high-risk anatomy, the patient was referred to our institution for coronary revascularization. The patient was taking daily aspirin in addition to oral hypoglycemic and anti-hypertensive therapies. Patient management. Both surgical and percutaneous revascularization alternatives were presented to the patient and her family. The patient clearly preferred to proceed with percutaneous revascularization following explanation of risks and benefits of both options. Subsequently, the patient underwent cardiac catheterization and percutaneous revascularization of the LAD and D2 lesions as described hereafter. The patient received intravenous abciximab and a 600 mg oral load of clopidogrel prior to coronary intervention. Using an 8 French JL-4 guiding catheter (Cordis Corporation, Miami, Florida) to engage the left main coronary artery, a 0.014" BMW wire (Guidant Corporation, Santa Clara, Calif.) and a 0.014" Wizdom wire (Cordis Corporation) were placed into the distal LAD and D2, respectively. The LAD was pre-dilated at the level of the D2 bifurcation with a Maverick 3.0 x 15 mm balloon (Boston Scientific/Scimed, Inc. Maple Grove, Minn.), and the ostial D2 was pre-dilated with a Maverick 2.0-9 and Cutting 2.5 x 6 mm (Boston Scientific/Scimed, Inc.) balloons. Following balloon dilatation, the presence of a longitudinal dissection was noted in the mid LAD and ostial D2 (Figure 2). A specially designed stent with sidebranch cell opening and protection, the AST-SLK-View 3.5 x 17 mm stent (Advanced Stent Technologies Inc., Pleasanton, California), was advanced over both wires into the LAD. Considerable guiding catheter support required “deep-throating” of the guide into the proximal LAD in order to optimally position the stent. Figure 3 shows the pre-deployment position of the stent in the mid LAD, with a special attention to the presence of an opaque marker directed into the ostial D2 at a 45-degree angle. The stent was subsequently deployed at 11 atmospheres and the stent balloon was successfully retrieved, while keeping both LAD and D2 wires distally. Following LAD stenting, we noted the presence of a residual dissection in the proximal D2 (Figure 4) and subsequently performed “kissing” dilatation of the mid LAD and proximal D2 with a Quantum Maverick 3.5 x 15 mm balloon(Boston Scientific/Scimed, Inc.) and a Maverick 2.5 x 15 mm balloon (Boston Scientific/Scimed, Inc.), respectively (Figure 5). Given suboptimal angiographic results in the proximal D2 (Figure 6), we proceeded with stenting the ostial D2 with a Pixel 2.5 x 8 mm stent (Guidant Corporation), while using the “T-stenting” technique, thus pulling on the D2 stent with an inflated balloon in the mid LAD upon stent deployment (Figure 7). Of note, no difficulties were encountered upon balloon and stent passage into the D2 through the struts of the deployed AST-SLK-View LAD stent. Final angiographic results were very adequate, without residual angiograhic stenoses in the bifurcation segment of interest (Figure 8). The patient was kept in hospital for observation and intravenous hydration. She was discharged home 24 hours following the procedure without any complications and remains free of anginal symptoms eight months after percutaneous coronary revascularization. How Would You Manage This Case? William W. O’Neill, MD Divison of Cardiology William Beaumont Hospital Royal Oak, Michigan his case nicely demonstrates the challenge that bifurcation stenting poses to the interventional cardiologist in 2003. Most previous technical challenges to PCI, including flow-limiting dissection, abrupt occlusion, inability to dilate lesions, and inability to cross lesions have been overcome by stent implantation. How major side-branches are handled remains problematic. Two main goals of treatment need to be kept in mind. First, the acute result has to be acceptable. Side branch occlusion will occur in 30% of cases when the ostium of the side branch is severely compromised, as it was in this case. If the side branch supplies a large portion of viable myocardium, then a large infarction could occur. Of paramount importance, however, is the fact that an excellent anatomic result is required in the parent vessel. Ideally, excellent anatomic results are needed in both branches, but if one has to prioritize, then the parent must be well treated. The second main management objective is to provide good long-term results. While we have made great technical advances such as the bifurcation stent used in this report in getting superb anatomic results, there still appears to be a high rate of recurrent ischemia in side branches, irrespective of treatment, including the use of drug-eluting stents with “crush” technique. Whether side branch ishemia even needs repeat intervention is open to debate. It is likely that cases like this one would actually have better long-term results with LIMA-to-LAD and vein graph-to-the-diagonal. These facts must be discussed with the patients prior to intervention. A 75-year-old grandfather may have entirely different social needs and objectives (as well as entirely different procedural risks) than a 45-year-old airline pilot. Because of the complex nature of these interventions, an unhurried discussion should take place and “ad hoc” procedures should definitely not occur. Howard C. Herrmann, MD Director, Interventional Cardiology & Cardiac Catheterization Lab University of Pennsylvania Medical Center Philadelphia, Pennsylvania This case illustrates a novel approach to PCI of a bifurcation lesion, namely the use of T-stenting utilizing an investigational side-aperature stent. Although the initial angiographic result was excellent, more traditional approaches need to be considered until this device receives FDA approval. Furthermore, the current availability of drug-eluting stent technology make this a suboptimal approach in this patient. The simplest approach would be to dilate the origin of D2, either conventionally or with a cutting-balloon, followed by placement of an LAD stent across its origin. In my experience, the side-branch is rarely totally-occluded, particularly with the use of an aggressive anti-platelet regimen (as was utilized in this patient). However, the need to re-enter the side branch through the side holes of the stent to “touch-up” a pinched ostium is frequent. An alternative approach would be a T-stent technique, placing the side branch stent first. With this approach, it may be difficult to precisely place the side branch stent without leaving a segment of stent in the LAD or a segment of diseased vessel not-stented. The side-aperature stent may improve the deliverability of the side branch stent, but won’t address the problem above much better. A true culotte stent approach would better cover all of the diseased vessel walls and usually gives a superb angiographic result. However, culotte-stenting is associated with a high rate of restenosis. For all of these reasons, I would approach this lesion with 2 sirolimus-eluting stents. In a diabetic with a small side branch (2.5 mm diameter) and a complex lesion, the benefit of reduced restenosis with a drug-eluting stent (DES) would outweigh the small benefit of utilizing a side-aperature bare stent. I would double-wire the lesion and place a 2.5 x 8 mm DES at the origin of the diagonal branch extending slightly into the LAD and then crush it with a second DES in the LAD. Although the long-term results of the crush technique have not been rigorously studied, early small series have not demonstrated increased rates of subacute thrombosis, and confirmed the benefit of DES for restenosis reduction. An example of this approach is shown in the figure. Jeffrey A. Werner, MD Vice President, Cardiovascular Services Mercy Health Systems of Northwest Arkansas, Rogers, Arkansas Dr. Halabi and colleagues demonstrate a possible solution to one of the most difficult and perplexing problems that remain in interventional cardiology: the bifurcational lesion. The Palmaz-Schatz stent was approved by the FDA in the United States in 1994. Once interventionists moved up the learning curve of coronary stenting, subsets of coronary anatomy began to emerge that remained challenging. The so-called bifurcational lesion remains one of those subsets and remains a patient group frequently requiring cardiac surgical referral. For perhaps some 5 years, a solution to bifurcational lesions has been promised. There have been many proposals but none, to my knowledge, has yet received FDA approval in the U.S. Most devices have been “pant-leg” type stents, and some variations of these have had success in the periphery. The coronary vasculature has proved more challenging, primarily due to size considerations. While the version of this investigational stent used by Dr. Halabi and colleagues in this case was bulky and difficult to place, by description, this same device — but with lower profile — is apparently now being evaluated (personal communication) and seems very promising. The advantage of this design, of course, is the limitation of the amount of metal structure needed in the side branch arm while maintaining side branch access should this vessel become compromised. Others have promoted variations of “kissing” stent approaches including so-called “crush” stenting. While an acceptable acute result may be atttainable, the amount of vessel trauma inherent in this technique would intuitively suggest that the risk would be increased for both late subacute thrombosis and/or intimal hyperplasia. We do not have large prospective series comparing these outcomes to CABG, for example, or to the provisional stenting approach. The issues, in my mind, are two-fold. First, how much disease is actually in the side branch? Second, is the plaque burden at the bifurcation such that plaque shift seems likely? When faced with this important decision, namely to send the patient to surgery or to attempt complex angioplasty, every extra effort would seem worthwhile. When available, IVUS can be very helpful in this setting. If the side branch seems to have little inherent disease, stenting of the parent vessel may be adequate. Should some plaque shift occur, simple PTCA to the side branch can usually be accomplished. When there is heavy plaque burden to both the parent vessel and the branch, so-called “kissing” stents can usually be placed with particular care to ensure that the parent vessel stent can be fully expanded. Essentially, this is a variation of so-called “T-stenting” with the parent vessel stent allowed to cross the orgin of the branch after the branch stent is placed. Newer models of most stents provide low profile, deliverability and good scaffolding, but also strut technology that allows much easier side branch access after deployment. With these tools, any of the above approaches are technically possible. In fact, with the availability of drug-eluting stents, the restenosis rates (but possibly not the subacute thrombosis rates) could be in the acceptable range. We await large series to confirm this. Indeed, the “investigational” bifurcational stent demonstrated in this case by Dr. Zidar could allow simpler placement issues and less potential vessel trauma which should translate to lower restenosis rates, particularly if these can ultimately be drug-coated. Notwithstanding all of the above mentioned encouraging developments, surgical coronary revacularization using arterial conduits and, when possible, off-pump techniques could be safer in terms of myocardial necrosis and preferable in terms of durability of the result in the appropriately selected patients. A catheter-based device solution in this difficult patient subset with low TVR rates would be very welcome indeed.