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Chapter 3: Bifurcation Stenting

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BIFURCATION STENTING

Victor H.T. Chen, MBChB, FRACP Samin K. Sharma, MD, FACC

EXECUTIVE SUMMARY Coronary bifurcation lesions represent an area of ongoing challenge in interventional cardiology. Contemporary studies using drug-eluting stents report a reduction in main vessel (MV) restenosis into the single digits compared with historical controls; however, residual stenosis and restenosis at the side branch (SB) ostium remain an issue. Based on recent randomized trials, the strategy of stenting the MV with provisional SB stenting is the current favored approach, although there are circumstances in which a two-stent strategy may be preferred, such as in the presence of a large SB that supplies a significant area of myocardium. Multiple two-stent bifurcation strategies exist, including T-stenting, V-stenting, simultaneous kissing stents, the crush, and the culotte. While each strategy has its own advantages and disadvantages, direct comparisons with provisional SB stenting or with each other remain limited. Dedicated bifurcation stents may some day significantly change the way in which bifurcation lesions are approached.

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Chapter 3: Bifurcation Stenting Introduction Coronary bifurcations are prone to develop atherosclerotic plaque due to turbulent blood flow and high shear stress. Bifurcation lesions account for approximately 15% of all percutaneous coronary interventions (PCI). In comparison to other PCIs, bifurcation interventions have lower rates of procedural success, higher cost, higher resource utilization, longer hospitalization, and higher rates of clinical and angiographic restenosis (1). Drug-eluting stents (DES) have resulted in a reduction of main vessel (MV) restenosis in comparison to historical controls. However, residual stenosis at the ostium of the side branch (SB) and longterm restenosis remain problems. Stenting the MV with provisional SB stenting is the prevailing approach, although certain anatomical configurations, a desire for an optimal acute angiographic outcome, and a perception that it may lead to better long-term success often drive the use of a two-stent strategy. In the era of DES, various two-stent techniques are available that allow stenting of large side branches in a way that ensures optimal lesion coverage and drug elution by the stent platform (Figure 1). Anatomical Considerations Coronary bifurcations have been classified according to the angulation between the MV and the SB, and according to the location of the plaque burden. A Y-angulation is less than 70 degrees and allows easy wire access to the SB, but plaque shifting is potentially more pronounced and precise stent placement with complete ostial coverage is often difficult or geometrically impossible. With a T-angulation, the angle between the MV and SB is greater than 70 degrees and wire access to the SB is usually more difficult. However, plaque shifting is less frequent and precise stent placement with complete ostial coverage is technically easier and more likely. In terms of plaque distribution, there are two main classification systems of bifurcation lesions, the Duke (Figure 2) and the Lefevre (Figure 3) (2). Plaque occurring in the MV at or near the ostium of the SB is more likely to result in SB deterioration following a MV intervention. Routine vs. Provisional Side Branch Stenting The strategy to use one stent (in the MV) or two stents (one in the MV and one in the SB) for the treatment of bifurcation lesions has been long debated (3-5). The most important initial question is whether the SB is large enough (> 2.25 mm diameter) with a sufficient territory of distribution to justify intervention irrespective of the bifurcation pattern. If the SB is small (<1 .5 mm) and supplies a small area of myocardium, stenting the MV across the SB is preferred. If the SB is larger and a one-stent approach is used, there is usually the option of placing a second stent in the SB if there is a suboptimal result. This strategy is called provisional side branch stenting as opposed to the two-stent strategy of routine side branch stenting. Other procedural and technical considerations in deciding which strategy to use are the angulation between the MV and the SB, the estimation of plaque burden, and the distribution of plaque, either angiographically or by intravascular ultrasound. As mentioned, these considerations have a bearing on the risk of plaque shifting and branch deterioration following the intervention. A randomized trial utilizing the Cypher® sirolimus-eluting stent (Cordis, Miami Lakes, FL) compared a one- vs. two-stent strategy (6). Both techniques resulted in low rates of angiographic restenosis of the MV (around 5%). However, routine stenting of the SB (the two28

Chapter 3: Bifurcation Stenting stent strategy) was associated with a trend toward higher restenosis in the side branch (23% vs. 14%; p = 0.22) and higher overall target lesion revascularization (TLR) (9.5% vs. 4.5%; p = 0.42). Likewise, the NORDIC Bifurcation Study , a multi-center, randomized trial designed to compare provisional stenting with routine side-branch stenting randomized 413 patients with previously untreated (de novo) bifurcation lesions to either stenting of the MV (with bailout if necessary) or stenting of the MV and the SB. Results of this trial, which used the Cypher stent, were presented at the 2006 American College of Cardiology Innovation in Intervention Summit. The two-stent strategy was associated with longer procedural times, higher contrast utilization, and unexpectedly, increased post-procedural non-Q wave MI. In addition, it offered no advantage in 6-month target vessel revascularization (TVR). There was no difference in stent thrombosis between the two groups. Based on these data, current opinion favors provisional side branch stenting with placement of DES in the MV. Stenting of the SB is undertaken only if there is SB deterioration resulting in less than TIMI grade 3 flow, electrocardiographic changes, or persistent intraprocedural angina. However, generalizability of this strategy to all anatomic configurations is uncertain. In situations where the SB is large, severely diseased, or supplies a large area of myocardium, the two-stent strategy is still often preferred because of its superior acute angiographic result and the intuitive belief that it will yield a better long-term symptomatic and/or prognostic outcome. Techniques for Treating Bifurcation Lesions with Two Stents A number of two-stent approaches are currently used. These include T-stenting and its variations (modified and reverse), V-stenting, simultaneous kissing stents, the crush and its variations (reverse and step), and the Culotte. T-stenting The classic T-stenting technique begins with positioning a stent at the ostium of the SB, being careful to avoid stent protrusion into the MV. Some operators leave a balloon in the MV to further help delineate the MV and avoid protrusion of the SB stent into the MV (7). After deployment of the stent and removal of the balloon and wire from the SB, a second stent is deployed in the MV. A wire is then re-advanced into the SB, and final kissing balloon inflations are performed. Modified T-stenting is a variation performed by simultaneously positioning stents in the SB and the MV (8, 9). The SB stent is deployed first, and after wire and balloon removal from the SB, the MV stent is deployed. The reverse T-stenting technique is a provisional stenting strategy used when the SB deteriorates after stent deployment in the MV (Figure 4). This requires re-crossing the SB through the MV stent struts, followed by ballooning and stenting of the SB. Final kissing balloon inflations are recommended. T-stenting is simple and technically less demanding. However, most bifurcations have a vessel angulation of less than 70 degrees so this technique will lead to incomplete stent coverage and geographic miss at the ostium of the SB, and hence forfeiture of the expected DES advantages of lower restenosis and TLR. V-stenting and Simultaneous Kissing Stents (SKS) The V-stenting technique consists of delivery and implantation of two stents simultaneously (Figure 5). One stent is advanced in the SB and the other in the MV, with the 29

Chapter 3: Bifurcation Stenting proximal extent of both stents touching and forming a small proximal carina (< 2 mm). The vessel proximal to the bifurcation must be free of disease to utilize this technique. When there is disease in the MV proximal to the bifurcation, a longer carina (usually 3 mm) is required and an alternative technique is simultaneous kissing stents (SKS) (Figures 6 A-C). The type of lesions typically suitable for this techniques are located where the MV is large enough to accommodate two stents side-by-side, such as distal left main or proximal left anterior descending (LAD)/diagonal bifurcations lesions. In the situation of lengthy disease in the proximal MV, a further modification is the trouser SKS where three stents are implanted to avoid an excessively long double stent carina (Figure 7). The SKS technique involves using two appropriately sized stents, one in the SB (1:1 stent-to-artery ratio) and one in the MV (stent sized 1:1 to the MV after the bifurcation), with a side-to-side arrangement of the two stents in the proximal segment of the MV. In order to accommodate the two stents, the proximal part of the MV should be at least two-thirds of the aggregate diameter of the two stents (i.e., if two 3 mm stents are placed in the LAD and the diagonal branch, the proximal LAD diameter should be at least 4 mm). Stent lengths are selected to cover the diseased area. As is the case whenever two stent catheters are inserted simultaneously, a 7F or 8F guiding catheter (minimum internal diameter > 0.78 mm) is required. After wiring and pretreating the vessels, two stents are advanced one by one into the SB and MV. They are then pulled back into the bifurcation making a "Y" configuration to completely cover the proximal end of the lesion in the MV. Once stent positions are confirmed, they are deployed with simultaneous inflations. This is followed by a second dilation of the MV stent to high pressures in order to fully expand it while the SB stent balloon remains deflated. When the MV stent balloon is deflated, a moderate to high-pressure dilation of the SB stent alone is performed. The final step is a simultaneous inflation of both stent balloons in order to form a uniform carina. For the trouser SKS technique, a large stent is first deployed proximally over a single guidewire in the MV. Then, the SB is wired through the lumen of the proximal stent and two stents are advanced and deployed in the more distal MV and SB as described above. A non-randomized single institution study compared 100 bifurcation cases receiving SKS to 100 matched bifurcation controls receiving MV stenting with provisional SB stenting (10). The SKS group had lower in-hospital and 30-day major adverse cardiac events (MACE) rates than the controls, and the incidence of TLR was 5% in the SKS group and 18% in the controls (p = 0.004) (Figure 8). The same investigators later analyzed their single-institution series of 200 consecutive patients who had SKS using sirolimus-eluting stents (11). Procedural success was 100% for the MV and 99% for the SB. In-hospital and 30-day MACE rates were 3% and 5%, respectively. At a mean follow-up of 9 months, the incidence of TLR was 4% (Figure 9). An advantage of SKS is that wire access to either branch is never lost so there is no need to re-cross stent struts. This reduces procedural time, radiation exposure, and contrast use. In addition, SKS provides definite side branch coverage by the DES platform, which likely translates to lower restenosis and TLR (a currently tested hypothesis). The main disadvantage of SKS is the persisting metal carina, which not only presents a theoretically increased risk of stent thrombosis necessitating a prolonged antiplatelet regimen, but also creates a technical challenge if reintervention of the vessel is required. 30

Chapter 3: Bifurcation Stenting

The Crush Technique The crush technique was introduced at approximately the same time that DES became available (Figure 10). As with SKS, a 7F or 8F guiding catheter is required. Two stents are placed in the MV and the SB, with the former placed more proximally than the latter. The stent of the SB is deployed, and its balloon and wire are removed. The stent subsequently deployed in the MV flattens the protruding cells of the SB stent. Wire re-crossing and dilation of the SB with a balloon having a diameter at least equal to that of the stent, followed by final kissing balloon inflation, is recommended. Final kissing balloon inflations are done to obtain better strut contact against the ostium of the SB, optimizing drug delivery. Final kissing balloon dilation after crush stenting with DES is associated with more favorable long-term outcomes, reducing SB restenosis and the need for TLR (12). A modification of the crush technique, the reverse crush, is a variation of provisional SB stenting and can be done through a 6F-guiding catheter. If the result of the SB is suboptimal after a stent is deployed in the MV, a second stent can be advanced into the SB and left in position without being deployed. Then a balloon sized according to the diameter of the MV is positioned within the previously deployed MV stent at the level of the bifurcation. The stent in the SB is retracted 2 to 3 mm into the MV and deployed. Following removal of the SB wire and stent balloon, the balloon in the MV is inflated at high pressure. The final steps involve re-crossing into the SB and performing a final kissing balloon inflation. The main advantage of the crush is that the immediate patency of both branches is assured. In addition, this technique should provide excellent coverage of the ostium of the SB. However, the mandatory final kissing balloon inflations makes the procedure more laborious because of the need to re-cross multiple stent struts with a wire and a balloon. Registry data has demonstrated relatively good outcomes with the crush technique, reporting a 6-month TLR rate of 11.3%, with the majority of restenosis occurring at the side branch ostium (13). The optimal technique to achieve adequate SB ostial expansion and reduce restenosis without causing MV stent distortion is still debated (14). It should be noted, however, that the efficacy of this technique in the left main bifurcation is uncertain. Left main stenting was found to be an independent predictor of TLR when using the crush technique with DES. Furthermore, the crush technique may be associated with an increased rate of stent thrombosis (15). The Culotte Technique The culotte technique uses two stents and leads to full coverage of the bifurcation (Figure 11). Both branches are wired and pre-dilated. First, a stent is deployed across the smaller, more angulated branch, usually the SB. Next, the non-stented branch is rewired through the struts of the stent and dilated. A second stent is then advanced and expanded in the non-stented branch, usually the MV. Finally, kissing balloon inflation is performed (16). This technique is suitable for all angles of bifurcations and provides near-perfect coverage of the SB ostium. It can also be performed through a 6F-guiding catheter. However, it leads to a high concentration of metal with a double-stent layer at the carina and in the proximal part of the bifurcation. Currently there is only limited data regarding outcomes with the culotte 31

Chapter 3: Bifurcation Stenting technique using DES (17). The main disadvantage of the technique is that rewiring both branches through the stent struts can be difficult and time consuming. Lesion Preparation and Antiplatelet Therapy Especially with DES where homogeneous drug delivery is paramount to optimal outcomes, thorough lesion preparation including debulking for very calcified lesions is necessary in order to ensure symmetrical stent expansion and to avoid malapposition. In addition, the large amount of metal with many of the bifurcation stenting techniques creates a theoretical increase in the risk of stent thrombosis. This has been suggested empirically, but the rates appear to be within a reasonable safety margin (18,19). Still, many favor a slightly more aggressive antiplatelet regimen of clopidogrel for at least one year and a minimum of 162 mg/d of aspirin for life. Conclusions Based on the size of the side branch, an algorithm can be created for the treatment of bifurcation lesions (Figure 12). Ongoing randomized trials including CACTUS (Coronary bifurcations: Application of the Crushing Technique Using Sirolimus-eluting stents), which is comparing a provisional SB stenting strategy with the crush technique using sirolimus-eluting stents, and Precise-SKS, which is a pilot trial for the treatment of true bifurcation lesions with simultaneous kissing stents, may help clarify if and when there is an advantage to a two-stent strategy with bifurcation lesions. In addition, dedicated bifurcation stents, such as the PetalTM (Boston Scientific, Natick, MA), are being developed and studied (Figure 13). These stents have the potential to markedly change the way in which bifurcation lesions are intervened upon in the future, particularly once they are designed with drug-elution.

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Chapter 3: Bifurcation Stenting

Figure 1. Various Techniques for Stenting Bifurcation Lesions

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Chapter 3: Bifurcation Stenting

Figure 2. Duke Classification of Bifurcation Lesions

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Figure 3. Lefevre Classification of Bifurcation Lesions

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Figure 4. The Reverse T-stenting Technique

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Figure 5. The V-stenting Technique

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Figure 6A. The "Simultaneous Kissing Stents" Technique

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Figure 6B. The SKS Technique for a Calcified Unprotected Left Main Coronary Artery Bifurcation Lesion

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Chapter 3: Bifurcation Stenting

Figure 6C. The SKS Technique of a Distal Left Main Bifurcation with a Subtotally Occluded Ostial LAD

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Figure 7. The Modified SKS (Trouser SKS) Technique (for long lesions)

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Figure 8. Follow-up Results of SKS vs. Conventional Stenting Techniques

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Figure 9. SKS-DES Technique for Bifurcation Lesions

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Figure 10. The Crush Technique

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Chapter 3: Bifurcation Stenting

Figure 11. The Culotte Technique

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Figure 12. Interventional Algorithm for Bifurcation Lesions

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Figure 13. The PetalTM Stent

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Chapter 3: Bifurcation Stenting References 1. Dauerman H, Higgins P, Sparano A, Gibson CM, Garber GR, Carrozza Jr. JP et al. Mechanical debulking versus balloon angioplasty for the treatment of true bifurcation lesions. J Am Coll Cardiol 1998;32:1845-1852. 2. Lefevre T, Louvard Y, Morice MC, Dumas P, Loubeyre C, Benslimane A et al. Stenting of bifurcation lesions: classification, treatments, and results. Cathet Cardiovasc Intervent 2000;49:274-283. 3. Al Suwaidi J, Berger P, Rihal C, Garratt KN, Bell MR, Ting HH et al. Immediate and longterm outcome of intracoronary stent implantation for true bifurcation lesions. J Am Coll Cardiol 2000;35:929-936. 4. Yamashita T, Nishida T, Adamian M, Briguori C, Vaghetti M, Corvaja N et al. Bifurcation lesions: two stents versus one stent - immediate and follow-up results. J Am Coll Cardiol 2000;35:1145-1151. 5. Pan M, de Lezo SJ, Medina A, Romero M, Hernández E, Segura J et al. Simple and complex stent strategies for bifurcated coronary arterial stenosis involving the side-branch origin. Am J Cardiol 1999;83:1320-1325. 6. Colombo A, Moses J, Morice M, Ludwig J, Holmes D, Spanos V et al. Randomized Study to Evaluate Sirolimus-Eluting Stents Implanted at Coronary Bifurcation Lesions. Circulation 2004;109:1244-1249 7. Kini A, Moreno P, Steinheimer A, Prattipati M, Suleman J, Kim M et al. Effectiveness of the Stent Pull-Back Technique for Non-Aorto Ostial Coronary Narrowings. Am J Cardiol 2005;96:1123-1128. 8. Colombo A, Stankovic G, Orlic D, Corvaja N, Liistro F, Airoldi F et al. Modified T-stenting technique with crushing for bifurcation lesions: Immediate results and 30-day outcome. Cathet Cardiovasc Intervent 2003;60:145-151. 9. Kobayashi Y, Colombo A, Akiyama T, Reimers B, Martini G, di Mario C. Modified "T" stenting: a technique for kissing stents in bifurcational coronary lesions. Cathet Cardiovasc Diag 1998;43:323-326. 10. Sharma S, Ahsan C, Lee J, Kim M, Fisher E, Steinheimer A et al. Simultaneous kissing stents (SKS) technique for treating bifurcation lesions in medium-to-large size coronary arteries. Am J Cardiol 2004;94:913-917. 11. Sharma SK. Simultaneous kissing drug-eluting stent technique for percutaneous treatment of bifurcation lesions in large-size vessels. Catheter Cardiovasc Interv 2005;65:10-16. 12. Ge L, Airoldi F, Iakovou I, Cosgrave J, Michev I, Sangiorgi G et al. Clinical and Angiographic Outcome After Implantation of Drug-Eluting Stents in Bifurcation Lesions With the Crush Stent Technique: Importance of Final Kissing Balloon Post-Dilation. J Am Coll Cardiol 2005;46:613-620. 13. Moussa I, Costa RA, Leon MB, Lansky AJ, Lasic Z, Cristea E, Trubelja N, Carlier SG, Mehran R, Dangas GD, Weisz G, Kreps EM, Collins M, Stone GW, Moses JW. A prospective registry to evaluate sirolimus-eluting stents implanted at coronary bifurcation lesions using the "crush technique". Am J Cardiol 2006;97:1317-1321. 14. McNab DC, Ormiston J, Webster MWI. Bifurcation coronary lesions and the "Crush" technique. J Am Coll Cardio 2006; 47: 2566­7. 15. Hoye A, Iakovou I, et al. Long-term outcomes after stenting of bifurcation lesions with the "Crush" technique. J Am Coll Cardiol 2006; 47: 1949­58. 16. Chevalier B, Glatt B, Royer T, Guyon P. Placement of coronary stents in bifurcation lesions by the "culotte" technique. Am J Cardiol 1998;82:943-949. 48

Chapter 3: Bifurcation Stenting 17. Hoye A, van Mieghem CA, et al. Percutaneous therapy of bifurcation lesions with drugeluting stent implantation: the Culotte technique revisited. Int J Cardiovasc Intervent 2005; 7(1): 36­40. 18. Ioannis I, Ge L, Columbo A. Contemporary stent treatment of coronary bifurcations. J Am Coll Cardiol 2005; 46: 1446­1455. 19. Iakovou I, Schmidt T, Bonizzoni E, Ge L, Sangiorgi G, Stankovic G et al. Incidence, prediction and outcome of thrombosis after successful implantation of drug-eluting stents. JAMA 2005;293:2126-2130.

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