Bifurcation lesions occur when the atherosclerotic plaque involves the origin of two separate arteries. A bifurcation is defined as a division of a main, parent branch into two daughter branches of at least 2.0 mm. Bifurcation lesions in coronary artery disease (CAD) are common, encompassing 15-18% of lesions treated with percutaneous coronary intervention (PCI). The optimal treatment for these lesions is subject to intense debate; current practice includes a variety of approaches. There is no data to suggest that stenting of a side branch improves outcomes over conventional balloon dilation of the side branch origin. In fact, sidebranch stenting may be associated with a higher risk of stent thrombosis. The consensus view at this time is that if there is adequate flow in the side branch and no evidence of ischemia at the end of the procedure, then further dilations of the side branch are not warranted.
Intravascular ultrasound indicates that the majority of plaque burden resides in the hips of the lesion and not at the flow divider or carina of the lesion. The hips of the bifurcation are areas of low shear stress where plaque accumulates.
Bifurcation lesions are classified according to the angulation of the bifurcation and plaque burden. This determines the ease of access to the side branch, plaque shift, and hence the preferred treatment strategy.
Several classifications have been proposed over the years to help better define the anatomy in bifurcation lesions. The original schemes published by Sanborn,[1] Safian,[2] Lefevre,[3] and Duke[4] are similar in their approach of using numbers or letters to represent various lesion types. However the absence of intuitive correlations between the various lesion type and associated classifications makes it difficult to remember and apply these classifications in routine clinical practice.
Shown below is an image depicting the modified Duke and ICPS classification systems for coronary artery bifurcation.
Image is adapted from definition and classification of bifurcation lesions and treatments.[5]
Medina et al.[6] subsequently published their classification which assigns a suffix of 1 (diseased) or 0 (not diseased) to the proximal main branch, side branch and distal main branch, respectively. According to Medina classification, a diseased artery is defined as having a stenosis of ≥ 50%. This classification allows for easy remembrance and it has since become the most commonly used scheme for defining anatomy of bifurcation lesions. However, Medina classification does not take into account the side branch size nor the side branch angle.
Shown below is an image depicting Medina classification for coronary artery bifurcation.
Image is adapted from classification and treatment of coronary artery bifurcation lesions: putting the Medina classification to the test.[7]
Coronary artery bifurcation is detected on angiography. Shown below are an animated and a static angiogrpahy images depicting bifurcation of a left coronary artery lesion. Encircled in yellow in the image on the right is the bifurcated lesion. Note that the lesion at the bifurcation has a "Mercedes" like shape which is outlined in yellow in the picture on the right.
In the stent era, the use of angioplasty in a compromised side branch can lead to stent deformation in the main branch. Studies have also demonstrated that patients undergoing PCI of a main vessel were at an increased risk for a MI within 30 days of their procedure if the stent compromised a side branch.
If there is a lesion at the origin of a side branch, the consensus view is that this should be dilated before treating or stenting the main vessel.
Guiding Catheter Selection in the Management of Bifurcation Lesions[edit | edit source]
Frequently large guide catheters (7F and above) are used to accommodate the multiple wires and the multiple simultaneous devices that are used in the treatment of a bifurcation lesion. Larger guiding catheters accommodate the use of multiple balloons for the kissing technique, and allow for the use of both balloons and stents as needed. It should be noted that 6F guiding catheters can be used for kissing balloon inflations.
Guidewire Selection And Technique in the Management of Bifurcation Lesions[edit | edit source]
Oftentimes operators will use two different wires so that it is clear which wire is which on the fluoroscopy screen. In general the more difficult lesion is crossed first. If the wire cannot be passed, then a hydrophilic wire can be used and if necessary a balloon can be inflated at low pressure to deflect the wire into the side branch.
Some operators advocate placement and retention of the wire in the side branch and stenting over this wire. These operators have hypothesized that this improves the geometry of the side branch and makes it more accessible to wiring through the stent strut for a kissing balloon inflation at the end of the case. This technique does. The risk of wire entrapment and wire fracture and should be used with extreme caution. This is not a technique utilized by the editor C. Michael Gibson M.S., M.D..
The single stent technique (also known as “provisional stenting”) is most commonly adopted. It involves stenting the main branch and then rescuing the side branch with either balloon angioplasty or stenting if necessary.
This involves stenting the side branch first to cover the ostium and then stenting the main branch. This approach can be difficult if the angle of the side branch is not 90 degrees and thus not allowing perfect alignment of the two stents. In this situation, there will either be a side branch stent strut protruding into the main vessel or incomplete coverage of the side branch ostium.
The modified T-stent approach (also known as “blocking balloon technique”) positions the side branch stent followed by a balloon placed in the main branch at the bifurcation. The main branch balloon is inflated first at low pressure to provide support against which the side branch stent can be aligned more accurately to cover the ostium without protruding. The side branch stent is then deployed followed by main branch stent deployment.
In the TAP (T and small protrusion) technique, the main branch is stented first, and then the side branch is reaccessed and redilated. The side branch stent is then placed with a small amount of strut protruding into the main branch. A main branch blocking balloon is then inflated simultaneously with the side branch stent.
If necessary, both the main branch and side branch are first wired with pre-dilation to allow for better access. The parent vessel is then stented before accessing the side branch through the main branch stent struts and a second stent is deployed in the side branch. This second stent extends back into the main branch stent. The main branch is then reaccessed through the side branch stent strut and both stents are kissing ballooned to complete the procedure, which allows flaring of the small protrusion.
This involves simultaneous stent deployment in parent and side branch vessels in parallel. This technique is useful in lesions that are difficult to cross, as wires do not need to be removed and lesions are not re-crossed. However, overdilation of the bifurcation carina may occur.
These are used when the stenosis is limited to the ostium of the side branch and the main vesseldistal to the side branch. In V-stenting, stents are deployed simultaneously without either stent extending proximally enough to cover the other. Y stenting is when an additional stent is placed proximally in the main branch.
Two stents are deployed with the side branch stent prior to main branch stent. The standard crush technique involves positioning both stents simultaneously. Next, the side branch stent is deployed and both the stent-delivery system and side branch guidewire are withdrawn. The main branch stent is then deployed – crushing the portion of the side branch stent in the parent vessel into the vessel wall. In such a case, the main branch proximal to the bifurcation lesion is scaffolded with a triple layer of stent. The side branch may then be re-wired and kissing balloon inflations employed in both vessels. This technique ensures stent coverage in the origin of the side branch and protects functional side branches during main branch stenting, however re-wiring and re-inflating balloons makes the procedure more technically challenging and time-consuming.
The inverse crush approach is similar to the standard crush approach, however, there are a few differences. The side branch stent is positioned more proximally than the parent vesselstent, the parent vesselstent is deployed first, and then it is crushed by the side branch stent when it is deployed. The main branch is then re-wired and kissing balloon inflations are employed. Hoye and colleagues found that the crush technique was effective with low rates of target lesionsrevascularization and major adverse cardiac events (MACE), except in left main disease. They also noted that the final kissing balloon inflation significantly decreased side branch restenosis rates. Furthermore, a study using registry data in Canada found that patients treated with the crush technique had decreased rates of MACE and angina compared to those patients with just main branch treatment.
Studies have shown there appears to be no overall benefit in adopting two stents strategies up front in comparison to the single stent strategy. Studies from the bare metal stent era demonstrated consistently that the single stent technique is superior to the two stents technique with less major adverse cardiac events (MACE). Studies from the drug eluting stent era continued to demonstrate higher overall restenosis rates in the two stents technique. Furthermore, two stents strategies appear to be associated with a higher risk for possible stent thrombosis in some of the studies performed. The NORDIC study[8] is a randomized control trial comparing the two strategies, and there was no significant difference in clinical outcomes including death, MI, TVR (target vesselrevascularization) or composite MACE. The stent thrombosis rate was low in both groups (0.5% in the main branch only vs 0% in the main and side branches together) as were main branch restenosis rates (4.6% in the main branch only vs 5.1% in the main and side branches together). The side branch restenosis rates were acceptable (19.2% in the main branch only vs 11.5% in the main and side branches together). In view of the above results, the current concensus is to treat the majority of bifurcation lesions with the single stent technique with a view of converting to provisional side branch stenting in cases of unsatisfactory angiographic result.
Older studies have suggested less revascularization and restenosis rates and higher success rates with DCA compared to PTCA, but DCA has also been associated with more ischemiccomplications. However, this has become less an issue in the current stent era, especially with the adoption of drug eluting stents.
The stent in the side branch may not adequately cover the side branch ostium. Alternatively, it may protrude into the parent vessel with T stenting, especially if the side branch is not at 90 degrees to the main branch (i.e. the lesion is angulated).
In difficult-to-cross lesions, kissing stents may be preferred. The wires need not be removed and the side branch and parent lesions need not be recrossed. A disadvantage is the potential for overdilation of bifurcation carina.
This approach ensures stent coverage in the origin of the side branch, but past studies suggest a possible increased stent thrombosis risk, a higher target lesionrestenosis rate, and more major adverse cardiac events in the setting of left mainstenting and among patients with multivessel disease.
Technical Considerations in Selecting a Strategy[edit | edit source]
Decision whether to stent compromised side branch based on size of vessel, amount of jeopardized myocardium, and probability of repeat revascularization
Side branch protection with a guidewire should be considered for any vessel >2.0 mm; in addition, if >50% stenosis of side branch is present, risk of side branch occlusion is >25% after dilation of parent vessel, and difficulty wiring branch vessel is anticipated
If side branch is <1.5 mm or small amount of viable myocardium is supplied, side branch protection not usually necessary
Kissing balloon inflations prevent plaque from prolapsing from one vessel to the other.
Sequential balloon inflation as opposed to kissing balloon dilation may lead to shifting plaque and side branch occlusion, but the same balloon may be used to dilate both vessels; parent vessel may remain underexpanded if balloon is sized according to caliber of vesseldistal to bifurcation
Final kissing balloon inflations prevent plaque from prolapsing from one vessel to the other and have been shown to result in better clinical outcomes, including lower restenosis rates, so generally this technique is recommended, especially when angioplasty or rotational atherectomy is used.
T stenting and crush stenting are well suited for branches that originate at 90-degree angles from parent vessel, because coverage of branch ostium is improved in these cases
T stenting and Y stenting are technically demanding; stent and retrieve technique may be preferred, depending on the operator's experience
Isolated side branch ostialstent does not require protection of parent vessel
Detailed Discussion of Specific Techniques[edit | edit source]
Using a minimum 7F guide system, both the parent and side branch are wired. Predilation is recommended to ensure optimal balloon expansion and ease stent delivery. It is important to identify which wire is placed in which branch. We recommend either using 2 separate colored guidewires, keeping a marker on 1 wire, or covering a wire with a sterile towel while not in use.
Any disease distal to the side branch should optimally be repaired before the final crush step.
The 1st stent is advanced into the side branch. This may require further predilation. Generally, the stent is advanced beyond the delivery point.
Angiography should now be performed to ensure adequate side branch coverage and stent deployment. Distal edge dissections or disease should be addressed before parent stent deployment. Once complete, the side branch wire is removed.
The side-branch is rewired. It is sometimes necessary to change wires to either a hydrophilic wire eg. Whisper, or Pilot 50 or 150, or ASAHI Fielder, one of increasing stiffness e.g. ASAHI Miracle Bros 3, or both e.g. Shinobi or Confienza.
Kissing balloons are inflated at the bifurcation. It is sometimes necessary to dilate the side branch with a small balloon (1.5 mm middle marker balloon) to facilitate a larger balloon for the kissing technique.
Despite excellent initial angiographic results, side branch restenosis is still a significant problem with Crush stenting (Up to 25% without kissing ballon inflation). However, most of the restenosis is silent. The above example used Cypher drug eluting stents in the side branch and parent vessels. The patient returned with positive stress testing 13 months later. Repeat angiography demonstrated a short segment of significant in-stentrestenosis.
Using a minimum 8F guide system, both the parent and side branch are wired. Predilation is recommended to ensure optimal balloon expansion and ease stent delivery. It is important to identify which wire is placed in which branch. Either using 2 separate colored guidewires, keeping a marker on 1 wire, or covering a wire with a sterile towel while not in use are recommended.
Any disease distal to the side branch or parent vessel should optimally be repaired before the kissing stents are deployed.
Both stents are advanced into the side branch and parent vessel. This may require further predilation. Generally, the stents are advanced beyond the delivery point. Operator preference differs with respect to amount of overlap. Some operators form a long segment of overlap (>5mm), while others try to minimize overlap. It is absolutely essential that both vessels are covered during the balloon inflation. Optimal placement is ensured by advancing both stentsdistal to the intended deployment site then pulling them back into position. The proximal marker segments should be aligned, with positional confirmation in at least 2 separate views.
Using 2 Insufflators, both stents are inflated to low pressure. Then alternating with side branch and parent branch inflated to optimal deployment size. There is some risk of over sizing the main branch with the overlapping stent segments. In the case where proximal disease may interfere with the 2 overlapping stents, a proximalstent may be deployed prior to inflating the 2 distalstents. (Pants-and-trousers technique)
Angiography should now be performed to ensure adequate side branch coverage and stent deployment. Distal edge dissections or disease should be addressed before wire removal from the vessels.
Variations of this method may be used to stent trifurcation disease. While an 8F catheter can be used depending on the stent system, optimally a 9 F system should be used in this situation.
A 6F guide system may be used with standard T stenting in which the side branch stent is deployed, followed by delivery and deployment of the parent stent. The modified technique, which is preferred by this operator, requires a minimum of 7F guide system.
Both the parent and side branch are wired. Predilation is recommended to ensure optimal balloon expansion and ease stent delivery. It is important to identify which wire is placed in which branch. We recommend either using 2 separate colored guidewires, keeping a marker on 1 wire, or covering a wire with a sterile towel while not in use.
The side branch stent is deployed. (Another option is to place a balloon in the parent branch and inflating to low atmospheres while pulling the side branch back. This may help ensure adequate coverage of the ostium.
Side branch wire is removed once adequate angiographic result confirmed.
The parent stent is deployed across the side branch.
Angiography should now be performed to ensure adequate side branch coverage and stent deployment. The parent stent is deployed.
The side-branch is rewired. It is sometimes necessary to change wires to either a hydrophilic wire e.g. Whisper, or Pilot 50 or 150, or Fielder, one of increasing stiffness e.g. ASAHI Miracle Bros 3, or both e.g. Shinobi or Confienza.
Kissing balloons are inflated at the bifurcation. It is sometimes necessary to dilate the side branch with a small balloon (1.5 mm middle marker balloon) to facilitate a larger balloon for the kiss.
Provisional T-Stenting involves the stenting the parent vessel and only the side branch if there is less than adequate side branch angiographic result. In this situation, the side branch may need to be serially dilated with up to a 2.5 mm balloon to ensure stent delivery. Final kissing balloons should be repeated.
Sometimes the side branch stent impinges on the parent lumen making delivery of the parent stent impossible. If this happens, dilation of the parent lumen with a balloon allows for stent delivery. This may create a partial or small area of crushed stents at the bifurcation and should be followed with kissing balloons.
Successful dilation of the parent vessel can be achieved in >85% of bifurcation lesions, but the success rates in side branch are generally much lower. Freshly occluded side branches can be opened successfully in >75% of cases if there is no pre-existing disease, but they can be opened in <50% of cases if there is pre existing disease (>50% stenosis). Side branch occlusion occurs more commonly after rotational atherectomy if the preexisting side branch ostialstenosis was >50%. Almost 40% of side branches will occlude after debulking with DCA in parent vessel, but these usually can be rescued with PTCA. Retrograde propagation of a dissection from the side branch into the parent vessel, as well as incomplete dilation and occlusion of side branch, can occur.
If the side branch wire is left in place when deploying the stent in the main parent vessel, then there is a risk of jailing the wire. If main parent branch stent extends a significant length proximal from the side branch (therefore jailing a longer length of wire) then consideration should be given to removing the wire prior to stenting. Forceful removal of the jailed wire can result in distalembolization of the guidewire.
New dedicated bifurcation stents have been developed to enhance treatment of these lesions. The AST petal DSX device[9] is a bare metal design that has “petals” in the main branch stent that allow guidewire access to the side branch and have outward-facing struts that protect the side branch ostium during main branch stenting. These petals cover the side branch ostium and allow balloondilation of the side branch after main branch stenting. The SLK-ViewTM device[10] has a “trap door” that allows access to the side branch after main branch stenting. The AXXESS stent device[11] is a DES device with a main branch stent that includes a flared edge designed to sit in the carina of the bifurcation lesions and allow stent placement in the side branch if necessary while protecting the ostium from plaque shift and side branch closure. The BIGUARDTM[12] is a DES that allows exchange of guidewires and other devices within the main branch which may facilitate changing from a one-stent to a two-stent technique.
2011 ACCF/AHA/SCAI Guidelines for Percutaneous Coronary Intervention (DO NOT EDIT)[13][edit | edit source]
"1. It is reasonable to use elective double stenting in patients with complex bifurcation morphology involving a large side branch where the risk of side-branch occlusion is high and the likelihood of successful side-branch reaccess is low.[17][18][19][20](Level of Evidence: B)"
The 16th expert consensus document of the European Bifurcation Club (2022)[edit | edit source]
The European Bifurcation Club has the following expert consensus recommendations: (DO NOT EDIT)[21][edit | edit source]
The Medina classification should be used in the description of bifurcation lesions.
A provisional stenting approach is recommended for most bifurcation lesions, however for complex lesions where the side branch is large and supplies a significant coronary territory, a two-stent approach may be used.
If a two-stent approach is used, lesion preparation should be performed in the main vessel and side branch first and final kissing ballooning and proximal optimization technique are mandatory.
There should be a low threshold for use of intracoronary imaging (IVUS or OCT).
↑Spokojny AM, Sanborn TM. The bifurcation lesion. In: Strategic Approaches in Coronary Intervention. Ellis SG, Holmes DR (Eds). Williams and Wilkins, MD, USA, 288 (1996)
↑Safian RD. Bifurcation lesions. In: The Manual of Interventional Cardiology. Safian RD, Freed M (Eds). Physician's Press,MI, USA, 222 (2001)
↑Lefèvre T, Louvard Y, Morice MC, Loubeyre C, Piéchaud JF, Dumas P (2001). "Stenting of bifurcation lesions: a rational approach". J Interv Cardiol. 14 (6): 573–85. PMID12053378. Unknown parameter |month= ignored (help)CS1 maint: Multiple names: authors list (link)
↑Popma JJ, Leon MB, Topol EJ. Atlas of Interventional Cardiology. Philadelphia: Saunders, 1994
↑ Louvard Y, Medina A, Stankovic G, Definition and classification of bifurcation lesions and treatments. EuroIntervention Supplement (2010) Vol. 6 (Supplement J) J31-J35. http://www.pcronline.com/eurointervention/J_issue/J31/
↑Medina A, Suárez de Lezo J, Pan M (2006). "[A new classification of coronary bifurcation lesions]". Rev Esp Cardiol (in Spanish; Castilian). 59 (2): 183. PMID16540043. Unknown parameter |month= ignored (help)CS1 maint: Multiple names: authors list (link) CS1 maint: Unrecognized language (link)
↑ 8.08.18.2Steigen TK, Maeng M, Wiseth R; et al. (2006). "Randomized study on simple versus complex stenting of coronary artery bifurcation lesions: the Nordic bifurcation study". Circulation. 114 (18): 1955–61. doi:10.1161/CIRCULATIONAHA.106.664920. PMID17060387. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Ormiston J, Webster M, El-Jack S, McNab D, Plaumann SS (2007). "The AST petal dedicated bifurcation stent: first-in-human experience". Catheter Cardiovasc Interv. 70 (3): 335–40. doi:10.1002/ccd.21206. PMID17722036. Unknown parameter |month= ignored (help)CS1 maint: Multiple names: authors list (link)
↑Ikeno F, Kim YH, Luna J; et al. (2006). "Acute and long-term outcomes of the novel side access (SLK-View) stent for bifurcation coronary lesions: a multicenter nonrandomized feasibility study". Catheter Cardiovasc Interv. 67 (2): 198–206. doi:10.1002/ccd.20556. PMID16404749. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Hasegawa T, Ako J, Koo BK; et al. (2009). "Analysis of left main coronary artery bifurcation lesions treated with biolimus-eluting DEVAX AXXESS plus nitinol self-expanding stent: intravascular ultrasound results of the AXXENT trial". Catheter Cardiovasc Interv. 73 (1): 34–41. doi:10.1002/ccd.21765. PMID19089934. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Chen SL, Zhang JJ, Ye F (2009). "Novel side branch ostial stent (BIGUARD): first-in-man study". Chin. Med. J. 122 (18): 2092–6. PMID19781290. Unknown parameter |month= ignored (help)CS1 maint: Multiple names: authors list (link)