Coronary Artery Bifurcation Lesion Classifications

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Coronary Artery Bifurcation Lesion

Classifications, Interventional Techniques

and Clinical Outcome

Mohammad Reza Movahed

Expert Rev Cardiovasc Ther. 2008;6(2):261-274.

Abstract

Percutaneous coronary intervention for the treatment of bifurcation lesions is associated with alower success rate and increased risk of subacute stent thrombosis and restenosis. The goal of

this manuscript is to review the current classification of coronary bifurcation lesions and

techniques. An algorithmic approach for the treatment of bifurcation lesions based on the

recently published simplified and comprehensive classification is proposed in this manuscript.

Coronary Artery Bifurcation Lesion Intervention: A Challenge

Coronary artery bifurcation lesions pose a major challenge for interventional cardiologists.Percutaneous coronary intervention (PCI) for the treatment of coronary artery bifurcation lesions

is associated with increased risk of complications.[1]

Two-stent techniques in the era of bare

metal stents (BMS) were associated with increased risk of short- and long-term adverseoutcomes.

[1-3]For this reason, the American College of Cardiology Task Force categorized

simple bifurcation lesions as type B lesions and complex bifurcation lesions with the risk of side

branch occlusion as type C lesions.[4]

Despite higher utilization of multiple stents in the treatment

of coronary artery bifurcation lesions, stent restenosis rate has been lower in the era of drug-eluting stents (DES).

[5-7]However, higher risk for subacute and late stent thrombosis is of major

concern.[5,8-13]

Currently, there is no guideline to address the choice of particular interventional

technique in regards to the specific anatomy of a given bifurcation lesion. There are few majorcoronary artery bifurcation lesion classifications published in the literature.[11,14-18]Most of these

classifications are confusing, difficult to remember and not clinically oriented.[18]

A

comprehensive, clinically oriented and simplified classification of coronary artery bifurcation

lesions and techniques has been published recently.[17]

Based on this classification, analgorithmic approach for the treatment of coronary artery bifurcation lesions is proposed in this

manuscript.
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Coronary Artery Bifurcation Classifications

Currently, there are six major bifurcation lesion classifications described in the literature. Of

these, four classifications were published in the era of BMS.[11,14-16]

They are all very similar indescribing a given bifurcation lesion. These classifications have not been adapted to the current

clinical practice of bifurcation intervention involving many complex interventional techniques,such as the kissing stent technique (KST) or the crush stent technique (CRT). They are similar intheir nomenclature. Different lesion types are named using numbers or letters with a lack of

association between the given names and anatomical abnormalities seen in these lesions.

For instance, Sanborn's Type I and Type III lesions describe two bifurcation lesions as two

different types with the same technical relevance (Figure 1).[15]

On the other hand, this

classification does not categorize technically important features of bifurcation lesions such as

angulation between the two branches or the size of the proximal healthy segment (important forthe KST). The Duke classification

[14]is similar to the Sanborn classification, which does not

describe the bifurcation angle or the proximal healthy segment. Furthermore, many lesions with

different names have similar features that are not important for technical decision making. Forexample, Duke type D or F lesions, involving both ostia, resemble Sanborn type B and C lesions

(Figure 1). For an interventionalist, there is no discernable difference between these lesions in

regards to choosing any specific technique. Therefore, it would be clinically and technicallyirrelevant to distinguish between these types. The same redundancy occurs in separating

bifurcation lesions into different types without technical relevance, as can be seen in Safian type

IA and IIIA[16]

and Lefevre type 1 and type 4 lesions[11]

(Figure 1). Again, there is no description

of proximal segment or angulation between the two branches in any of these classifications,which miss important technical information. Furthermore, there is no connection between the

lesion's types and the names, making it very difficult to memorize. These are the reasons why

these classifications have not found their ways into routine clinical practice.


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Figure 1.

Summary of currently published major coronary bifurcation classifications.

Two new bifurcation classifications have been published recently in order to overcome some ofthe limitations of previous classifications. The first attempt to simplify these classifications for

better memorization was successfully made by Medina et al.[19]

(Figure 1). They divided

bifurcation lesions into three segments: proximal segment of the main branch, side branch ostia,and distal segment of the main branch. Any involvement of each segment will receive the suffix

1, otherwise suffix 0 was assigned starting from left to right. For example, lesion 1,0,1 means

that proximal segment, and side branch ostia are diseased but the distal part of the main branch isfree of disease (Figure 1). This classification is easier to remember in comparison to older


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Figure 2.

Detailed structural description of the Movahed's coronary bifurcation classification with

modification of the 4th suffix. Reprinted with permission from The Journal of Invasive

Cardiology.

A large proximal segment is a requirement for the KST, an important feature of this

classification. The main requirement for performing KST is the presence of a large proximalhealthy segment that is at least as large as two-thirds of the sum of the diameter of both branch

vessels, which can accommodate two stents.[7]

The first suffix of this classification addresses this

feature. If the proximal segment is large enough, it is assigned the first suffix of L (for Largeproximal segment), whereas if the proximal segment is small (less than two-thirds of the sum of


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the diameters of both branch vessels) it is assigned the first suffix of S (for Small proximal

segment). Therefore, BL lesions are suitable for the KST, whereas BS lesions are not.[7]

The second suffix in this classification describes a very important feature of coronary artery

bifurcation lesions, which is the involvement of branches. If the ostia of both bifurcation

branches are involved in the significant atherosclerotic disease process, the suffix number 2 isused. It is well known that significant atherosclerotic involvement of both ostia dramatically

increases the risk of side branch occlusion during PCI or stenting of the main branch. In the

randomized trial comparing the new intravascular rigid-flex stent to the Palmaz-Schatz stents,atherosclerotic involvement of both branch ostia was associated with 40% occurrence of

myocardial infarction. However, if the side branch was not involved, myocardial infarction

occurred in only 4.7%.[21]

In an analysis of angiographic predictors of side branch occlusion, side

branch closure occurred in 65% of lesions if both ostia were diseased versus 4% in lesionswithout the side branch involvement.

[22]

If only the main branch is diseased regardless of whether it is in the proximal or distal segment,

suffix 1m is used. For involvement of the side branch only (or anatomically less importantbranch), suffix 1s is used. This distinction is important for technical decision making, which is

discussed later in detail.

The third important suffix in this classification describes the angulation of bifurcation branches,

which has been ignored in other classifications. Steep angulation makes access to the side branchdifficult after main branch stenting and is significantly associated with adverse outcome. Dzavik

et al.found that there was a significant increase in the long-term mortality in patients with highly

angulated lesions who were treated with the CRT.[23]

Furthermore, a steep angle is significantly

associated with the risk of abrupt vessel closure[24]

or side branch occlusion.[22]

Therefore, it isvery important that bifurcation classifications incorporate this important feature into

classification as has been done in the recent simplified classification. The suffix V is given forshallow angles less than 70 (which looks like a V) and suffix T is given for a bifurcation with asteep angle of more than 70 degree (which looks look like a T). For example, a BS2T lesion is a

bifurcation lesion (B for bifurcation) that has a small proximal segment (S for small, which is not

suitable for KST) with involvement of two ostia (2 for both ostia) in the disease process with asteep angulation (T for steep angulation since it looks like a T) of the branches. An example of

BL2V lesion can be seen on Figure 3.


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Figure 3.

An example of a BL2V lesion. A bifurcation lesion with a large proximal segment and

involvement of both ostia (2) with an angle of less than 70 (V) between the branches that wassuccessfully treated using the kissing stent technique.

This classification adds optional suffixes for other high-risk features at the end of theclassification symbols (in this classification LM was used for left main and CA for calcium).

However, an expansion of this classification can easily be done by adding an abbreviation of

other high-risk features to the end of the lesion description such as 'TO' (for total occlusion) or

'TR' (for thrombus-containing lesion). For example, for better communication and more detaileddescription of a bifurcation lesion, an interventionalist could describe a heavily calcified

thrombus containing lesion involving LM with small healthy proximal segment, involvement of

both left anterior descending arterty and circumflex ostia, and steep angulation as: BS2T-LM-

CA-TR lesion. However, for simplicity, an interventionalist could just use the importantanatomical features of this bifurcation lesion and describe it as BS2T lesion or only utilize the

most important suffix for a given technique and describe this lesion as BS, B2 or BT lesion.

A summary of currently available classifications can be seen in Figure 1. A more detailed

structural explanation of the newest comprehensive simplified classification can be seen inFigure 2.


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Interventional Techniques in the Treatment of Bifurcation Lesions

Several techniques have been described and used successfully in the treatment of bifurcation

lesions. Different names for similar bifurcational techniques have caused confusion in thepast.

[11,14-16,25-28]For example, the KST has also been described as 'V' stenting if proximal

overlap of both stents is too short.[7,25]

Recently, the European Bifurcation Club has divided bifurcation interventions into categories

depending on the location and timing of the first stent implantation. If the first stent is planted in

the main branch, it is called 'M' (for Main branch), if it crosses the bifurcation, it is called 'A' (forAcross) and if the stent is placed in the side branch first, it is called S (S for Side branch).

[20]This

nomenclature describes the location and sequential timing of bifurcation stenting. However, it

does not describe technical aspects of important interventional techniques using one or two

stents. Therefore, for simplification, the most common bifurcation techniques with regards tostenting have been recently classified into six categories

[17]: the one-stent technique (OST), the

stent with balloon technique (SBT), the KST, the T stent technique (TST), the CRT and the

cullotte stent technique (CUT) (Figure 4).

Figure 4.


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Interventional bifurcation techniques. CRT: Crush stent technique; CUT: Cullotte stent

technique; KST: Kissing stent technique; OST: One-stent technique; SBT: Stent with balloon

technique; TST: T stent technique.

When to Choose One- or Two-stent Techniques?

The simplest technique is one-stent technique (the OST or the SBT). The long-term outcome of

the OST has been at least as good as or even better than two-stent techniques regardless of stent

type. The only two-stent technique that has shown better long-term outcome in comparison to the

OST with regards to stent restenosis has been published by Sharma et al.[7]

using KST. Earliertrials comparing two-stent techniques have shown an increase in adverse outcomes in

comparison to the OST in the BMS era. Restenosis rate (57 vs 21%) and target lesion

revascularization were higher for stenting both vessels (43 vs 8%).[29]

This finding has been

confirmed by other studies.[1,3,30]

In order to decrease the restenosis rate, DES have been studiedin comparison to BMS. DES has consistently been found to be superior to BMS in the treatment

of bifurcation lesions with lower in-stent restenosis or target lesion revascularization.[31,32]

Using

two-stent techniques in the era of DES did not improve restenosis rate. Apart from the KST intwo large trials,

[7,33]other two-stent techniques have not been superior to OSTs. The first

randomized trial comparing two stent to OSTs showed no significant difference between the two

approaches.[5]

Various bifurcation techniques were used in this trial such as the TST and theKST. A modified TST was used in the majority of the cases (63.5%). With advancement in the

bifurcation interventions, stent restenosis rates have been lower using one- or two-stent

techniques. It usually depends on the disease burden of the side branch.[34]

For example, in the

Nordic study,[34]

the presence of over 50% lesions in the side branch was associated with arestenosis rate of 11-19%, whereas less than 50% side branch disease was associated with an in-

stent restenosis rate of 4.6-5%. The two randomized Nordic Bifurcation II and Bifurcations Bad

Krozigen studies were presented at the Trans Catheter Therapeutics meeting in November 2007

confirming the previous findings that the restenosis rate is not better using two stents.

Furthermore, the risk of subacute stent thrombosis has been higher using two-stent techniques inthe majority of trials.

[5,35,36]Conversely, provisional side branch stenting in B2 lesions (both ostia

are diseased) poses a high risk for side branch occlusion and increases procedural complication

rate, as described earlier. The risk of side branch occlusion in B2 lesions can be as high as 65%

depending on the side branch angle.[21,22]

Based on these trials, there is a general consensus thatif a bifurcation lesion does not have high-risk features for side branch occlusion, such as

involvement of both branch ostia (B2 lesions) or steep angulations (BT lesions), using one stent

techniques (the OST or the SBT) with provisional side branch stenting in the case of

unsatisfactory results in the side branch is the preferred technique. Otherwise, two-stent

techniques offer safer access to both diseased branches in the high-risk lesions. For easieradvancement of two stents in the bifurcation lesions, balloon predilation is recommended before

stenting. Any bifurcation intervention poses a high risk for acute side branch occlusion, whichmay require changes in the initial technique to a more complex interventional technique. This

may require larger guide catheter size and stronger guide support. Therefore, in high-risk

bifurcation lesion interventions, it is recommended to use a 7-Fr sheath size.

Technical Features


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One-stent Technique

The OST is based on a simple technique using one stent. This is the best technique in bifurcationlesions with a small side branch that can be ignored. This is also the best technique that is

suitable for BC (close to bifurcation) and BN (not a significant side branch) lesions or B1m

lesions when the side branch ostia is not involved (as the risk of side branch occlusion is smallwhen the side branch is not diseased).[22]

After the initial stent deployment in the main vessel, the

side branch will be left alone if no significant stenosis or plaque shift occurs at the side branch

ostium.

Stent Balloon Technique

The SBT uses one stent in the main branch and balloon angioplasty of the side branch ostium

when the side branch ostium is compromised after main branch stenting or the side branch has

significant disease. This technique is also very simple, but can be associated with a higher risk ofside branch occlusion in the high-risk lesions such as B2 lesions with difficulty to access the side

branch in BT lesions. B1m lesions are best suited for this technique if the side branch ostium iscompromised. It is important to use a short balloon for side branch angioplasty in order to

decrease trauma to the side branch vessel.

Kissing Stent Technique

The KST requires simultaneous advancement of two stents that are positioned side by side into

each bifurcation branch with the creation of a new carina. This technique is also known as V

stenting.[7,19,37]

The major advantage of this technique is the ability to maintain access to bothbranches at all times. However, the occurrence of an edge dissection or the presence of

additional stent struts in the main vessel poses a theoretical risk of stent thrombosis.

Nevertheless, based on the two recently reported studies,

[7,33]

the subacute stent thrombosis ratefor this technique has been low in the DES era. The most important anatomical requirement of

this technique is the presence of a large proximal segment in order to accommodate the proximal

ends of the two stents. Therefore, BL lesions with the proximal healthy segment of at least two-thirds of the sum of the diameters of both bifurcation branches are best suitable for this

technique. Furthermore, steep angulations may cause difficulty in advancing two stents

simultaneously, making BT lesions more risky with this approach. It is important to performfinal kissing inflation of both stents at a low pressure for optimal stent deployment. The sequence

of this technique is as follows. First, both stents will be deployed at a low pressure (6-8

atmospheres). Next, both stent balloons are deflated and each balloon is inflated sequentially to a

high pressure (14-16 atmospheres) followed by final inflation of both stent balloons at a lowpressure again at the end of the procedure. Figure 3 demonstrates one example of this technique

used in a BL2V lesion. The main drawback of this technique is the occurrence of proximal edge

dissection, which could be difficult to treat. In such cases, the KST can be converted to the CRT

by crushing the side branch stent with the ability to stent the proximal segment. A long proximaldisease segment may require initial simple stenting of the proximal segment in order to avoid

creating a long carina. This technique has the disadvantage of requiring a large at least 7 Fr

sheath size in order to advance two stents simultaneously.


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T Stent Technique

The TST requires positioning of two stents in a 'T' fashion. This technique has many other namessuch as 'modified T technique' or 'classic T technique'

[25,27,28,38]and there are many different

variations. The easiest and safest approach is a pullback technique where a stent is placed in the

side branch and a balloon in the main branch, which is inflated to a low pressure.

The side branch stent is then pulled back to the side branch ostium while a balloon is inflated at

low pressure in the main branch, protecting the main branch from excessive side branch stentmalposition into the main branch. After the stent deployment in the side branch, stenting of the

main branch is then performed if the main branch is compromised or has a significant lesion. A

different approach is also described as mini crush. In this approach, after initial balloon

predilatation, two stents are positioned simultaneously in both branches. Next, the side branchstent is inflated with minimal stent overhang in the main branch. After the removal of the side

branch stent balloon, the main branch stent is deployed. This will clear and push the minimal

side branch stent overhang back to the side of the vessel wall. Final kissing balloon inflation will

conclude the procedure.

It is also possible to stent the main branch first and then stent the side branch through the stentstruts with the risk that advancement of the side branch stent could be difficult. This is the best

suitable bail-out technique when after the initial main vessel stenting and side branch balloon

angioplasty, the side branch result remains suboptimal or major dissection of the side branchrequires additional stenting.

The loss of direct side branch access after the main branch stenting in comparison to the KST is amajor drawback of this approach. This technique can be best utilized in bifurcation lesions with

small proximal segments that are not suitable for the KST such as BS2 lesions. Other two-stent

techniques such as the CRT or the CUT can be used in B2 lesions based on operator expertise.

Crush Stent Technique

The CRT, pioneered by Colombo et al.,[27]

lost initial enthusiasm due to a high rate of subacute

thrombosis and difficulty to rewire the side branch for final kissing balloon angioplasty. It

consists of advancing two stents simultaneously into both bifurcation branches. The proximalsegment of the side branch stent is first deployed in the main branch and is then crushed to the

main branch vessel wall after stenting of the main branch. Modification of this technique is

called reverse crushing, which is done in the reverse fashion.[13,39]

If after the one-stent technique

the side brach ostium has significant lesion despite balloon angioplasty, reverse crush techniquecan be used as a bail-out technique. In this situation, a second stent is advanced into the side

branch though the main stent struts. Then, a balloon in the main branch is positioned at the level

of bifurcation. Next, the proximal part of the side branch stent is retracted into the main branchand deployed. After the removal of the side branch balloon, main branch balloon inflation will

crush the proximal side branch stent strut. Then, the final kissing balloon is performed. The main

advantage of this technique is that it is compatible with a 6 Fr size system. At the end of theprocedure, the side branch will be rewired and final simultaneous kissing balloon inflation is

performed. Although this technique can be utilized for most bifurcation lesions, steep


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angulations such as T lesions could make it difficult to rewire the side branch. Furthermore,

subacute stent thrombosis and side branch restenosis rates have been high.[9,10,13]

This technique

can be technically challenging, since rewiring of three stent layers could be difficult. For thesereasons, this technique has fallen out of favor. The CRT has a major limitation related to the

difficulty in rewiring and advancing an angioplasty balloon across three layers of stents. In order

to overcome this limitation, a modified version of the CRT, known as the sleeve technique, issuccessfully utilized clinically.[9,40]

This technique utilizes an angioplasty balloon first (asopposed to a stent) in the main branch after stenting of the side branch in order to crush the

proximal part of the side branch stent. Using only a balloon in the main branch for crushing has

the distinct advantage of having only two layers of stent in the side branch ostium for rewiring.Before final stenting of the main branch, the side branch ostium is rewired and ballooned

together with main branch balloon inflation (first kissing balloon) creating an open side branch

ostium. The side branch is now like a new sleeve giving the name of the sleeve technique. After

main branch stenting, rewiring of the side branch ostium is much easier since only one stentlayer needs to be recrossed for the final kissing balloon inflation. Using this technique,

successful final kissing balloon inflation could be performed in all patients in a small trial.

However, subacute stent thrombosis rate remains high at 2.4%.

[9]

Furthermore, this modificationadds substantial time, cost and complexity to the CRT procedure and there are no long-term

follow-up data available at this time. A modified TST, which is described in the previous section,

is called mini crush, which is now utilized by many interventionalists in order to avoid

positioning many layers of stents in the main vessel. The CRT, similar to the KST has thedisadvantage of requiring a large at least 7 Fr sheath size in order to advance two stents

simultaneously, unless reverse crush or sleeve technique is utilized.

Cullotte Stent Technique

The CUT, also described as Y stenting or 'trouser legs',[25,38,41]

was associated with high

restenosis rates in the past. However, it is gaining popularity in the era of DES. A small trial of

23 patients showed an encouraging low restenosis rate of 18% without any stent thrombosis.[42]

This positive result was confirmed in a recent trial comparing the provisional CUT with the TST.The CUT revealed a lower rate of target lesion revascularization of 8.9% in comparison with the

TST.[43]

Based on these two encouraging trials, the CUT may become the preferred technique.

This technique is useful as a bailout technique. In case of an unsatisfactory side branch resultafter main branch stenting using BST, the CUT can be utilized to resolve the problem. With this

technique, the operator should first stent the less angulated or most diseased branch vessel, and

then rewire the other branch through the stent struts. Next, the second stent is positioned across

the second branch with positioning of the proximal stent segment in the proximal part of thepreviously stented segment in the other branch. Final simultaneous kissing balloon inflation

should be performed in order to expand stent struts. This technique is suitable for T or V lesions

when both ostia of the bifurcation branches are diseased. The technique is best suitable for thelesions when the size of the side and main branches are similar. Otherwise, the proximal part of

the smaller stent could float in the larger branch making the rewiring for final kissing balloon

difficult.

Algorithmic Approach to the Treatment of Bifurcation Lesions


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A proposed algorithm for lesion specific techniques is illustrated in Figure 5. It is important to

visualize the bifurcation branches in order to assess if a lesion is a true bifurcation. If there is a

small space between the main and the side branch, the lesion will be categorized as BC lesion(close to bifurcation). These lesions are not true bifurcation lesions and should be treated with

careful positioning of one stent in the main branch before the bifurcation site. If the operator is

convinced that a bifurcation lesion is a true bifurcation lesion, then the next question is theimportance of the side branch vessel size. If the side branch vessel is small (usually less than 2-2.25 mm) or supplies small territory, the lesion should be classified as BN (nonsignificant

bifurcation). In this case, the side branch should be ignored and stenting of the main vessel

should be performed using the OST. In the case of side branch occlusion, a short attempt of sidebranch balloon angioplasty may be warranted if the patient is symptomatic.

Figure 5.

An algorithmic approach for the treatment of coronary artery bifurcation lesions based on the

lesion type.


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If the side branch is found to be important, the operator needs to evaluate atherosclerotic disease

involvement of the main and side branches. If only one ostium is involved, it is important to

know which branch is diseased. If the main branch is not involved, the operator shouldreconsider intervening on the side branch with a potential risk of injuring and compromising the

main branch. If the intervention can not be differed due to large side branch size, a OST with

pullback protection of the main branch should be used by positioning an inflated balloon at lowpressure in the main branch before ostial side branch stenting. This approach may prevent mainbranch compromise. Any major compromise to the main vessel will require further intervention.

If only the main branch ostium is involved in the disease process, the OST is the easiest preferred

technique with provisional side branch angioplasty or stenting if the side branch is compromisedafter main branch stenting.

If the interventionalist realizes significant involvement of both branch ostia, the OST poses ahigh risk for side branch occlusion. In the majority of cases, operators prefer two-stent

techniques in order to decrease the risk of side branch occlusion. The choice of two-stent

technique depends on the operator's expertise and preference. Based on simplicity and good

long-term outcome, the KST can be used in suitable lesions. Therefore, the proximal segment ofa bifurcation lesion needs to be assessed. If the proximal segment is large enough to

accommodate two stents in BL lesions, the KST can be used. If the proximal healthy segment issmall, other techniques need to be utilized depending on the branch angles.

If the branch angle is over 70, advancement of two stents into the side branch could be difficult.

Furthermore, the CRT is technically more challenging in angulated lesions and is associated withincreased adverse outcome in these lesions.

[23]Therefore, the operator should avoid the CRT in

angular BT lesions. If the branch angulation is less than 70, the TST runs the risk of missing the

side branch ostium. Therefore, the CUT or the CRT should be considered initially. If the TST isused, the pullback technique, also known as the mini crush technique, would be a better choice in

order to avoid missing the side branch ostium. An overview of this suggested algorithmic

approach to bifurcation stenting and intervention is shown in Figure 3. A summary of advantages

and disadvantages of each technique can be seen in .

Table 1. Summary of Advantages and Disadvantages of Different Bifurcation

Interventional Techniques

Technique Advantage Disadvantage

Best suitable

lesions Not suitable lesions

One stent

technique/

stent withballoon

technique

Easiest and

simplest initial

techniques byadvancing only

one stent in the

main branch

Risk of side branch

occlusion is higher,

particularly in B2lesions Rewiring of

the side branch can be

difficult if side branchballoon angioplasty or

stenting is necessary

after main branch

Close to

bifurcation but

not truebifurcation

lesions

Bifurcationlesion with a

nonsignificant

side branch Only

B2 lesions pose a

high risk for side

branch occlusion andrewiring difficulties

if further

intervention isneeded Particularly

B2T lesions which

make side branch


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stenting main branch

ostium isdiseasedOnly

side branch

ostium is

diseased

rewiring very

difficult

Kissingstent

technique

Least risk of sidebranch occlusion

as side branch

access ismaintained

throughout the

procedureOstial

side branchcoverage is

guaranteed

Requires largeproximal healthy

segmentRquires 7

Fr sheath size Longmain branch lesion

may require stenting

proximal main branch

disease first to avoidlong new carina

containing two stents

in the main vesselProximal or distaldissection can be

difficult to treat and

may require changingthe technique to more

complex crush

technique to treat

proximal dissectionTwo stents in the

main branch may be a

problem for futureintervention and may

pose unknown risk for

thrombosisPreliminary trials

have shown the least

risk of late or

subacute stentthrombosis with the

KST

Only BL lesionscan be treated

Particularly

BL2V lesionswith both ostial

disease and short

proximal main

branch diseasewith shallow

angle are best

suitable for theKST

Long main branchlesion will cause a

creation of a long

new carina with twostents in the main

branch. This may

increase the

theoretical risk forstent thrombosis or

increases difficulty

for future distalinterventionBTlesions with steep

branch angulation

can make it difficultto advance two

stents

simultaneously

T stent

technique

Can be easily used

as bail out

technique Easiesttechnique for

simultaneous

advancement oftwo stents Can be

easier using

Risk of difficulty or

inability to advancing

second stent acrossthe main stent struts if

the main branch is

stented first Difficultfor precise stent

position in the side

B2 lesions with

steep angle (B2T

lesions). Steepangle makes it

easier to position

the side branchstent in the side

branch ostium

BV (shallow

angulated) lesions

make it difficult toposition the side

branch stent


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balloon protection

in the main branch

branch and risk of

missing the sidebranch ostium Risk of

side branch stent

overhand in the main

branch Increasedoverall risk for

subacute stentthrombosis

Crush stenttechnique

Can be easilyperform in most

bifurcation lesions

initially Ostial side

branch coverage isguaranteed

Poses difficulty forrewiring the side

branch for final

kissing balloon

angioplasty (thesleeve technique, a

modification of the

CRT, can make theside branch accesseasier, see text)

Higher risk for stent

thrombosis andrestenosis Requires a

large at least 7 Fr

sheath size unless the

reverse crush or thesleeve technique is

used

B2V lesions BSlesions (lesions

with small

proximal healthy

segments makingthem not suitable

for the KST)

BT lesions haveshown worse long-

term outcome with

this technique

Cullotte

stenttechnique

This technique can

be used as bail outtechnique if the

side and main

branches have

similar sizeVeryeasy for side

branch stent

positioning once

the second stentcrosses the side

branch

Long-term results are

not well studiedCannot be easily

performed if the side

branch is much

smaller than mainbranchMany stent

struts in the main

branch may increase

the risk of subacute orlate stent thrombosis

Rewiring the main

branch can bedifficultAfter main

branch stenting, side

branch could bedifficult to rewire in

BT lesions

All B2V

lesionsBothbranches are

similar in size

BS lesion

If both branches are

markedly different insize BT lesions pose

the risk for side

branch rewiring and

stent crossing failure


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B2: Both ostia are significantly diseased; B2T: Lesions with ostial disease and steep angle; BS:Lesions with small proximal healthy segments making them not suitable for KST; BT: Steep

angulation; B2V: Both ostia are diseased with shallow angulation; KST: Kissing stent technique.

Other Technical Aspects of Bifurcation Intervention

Wiring Technique

It is very useful to maintain side branch access during PCI of bifurcation lesions. In the KST,

wire access to both branches is maintained at all times. Therefore, this technique poses the

lowest risk of side branch occlusion. All other techniques require removing the side branch wireat some point during the course of intervention. Some interventionalists advocate keeping and

jailing the side branch wire throughout the procedure after main branch stenting in order to have

a road map to the side branch for rewiring. This could be extremely helpful in the case of side

branch occlusion after main branch stenting. On the other hand, there is a theoretical risk andconcern of inability to remove the jailed wire at the end of the procedure. However, this risk

appears to be small.[38]

Many interventionalists remain uncomfortable with this approach. Thereare no data in the literature to systematically evaluate and compare the jailed wire technique

versus removing the side branch wire before the main branch stenting. There is currently no

consensus about these two wiring approaches.

Final Kissing Ballooning

In order to optimize stent geometry in the main and side branches, a final kissing ballooning is

recommended in procedures that require additional side branich intervention. This

recommendation is based on many trials indicating improvement in the long-term outcome usingthis technque.[11]

The superiority of final kissing balloon angioplasty has been clearly

demonstrated in many trials using the CRT.[28,35,36,44]

However, there is no randomized trial or

consensus statements to evaluate balloon sizing or balloon overlap for the kissing balloon

angioplasty. It is recommended to avoid significant stretching and upsizing of two balloonsduring final kissing inflation in order to prevent trauma or perforation to the vessel walls.

Selection of balloon diameter should be made based on the distal diameter of each branch. Short

balloons should be used in order to avoid inflation outside the stent preventing edge dissection.

In the side branch, the use of short balloons could reduce distal vessel injury. Inflation pressureshould be guided by the technique. Sequential high-pressure balloon inflation before final kissing

balloon angioplasty may be necessary for optimal stent expansion. For example, after initial

deployment of two stents using KST, each stent balloon should be inflated to high pressuresequentially before final simultaneous low-pressure kissing balloon angioplasty. As mentioned

earlier, coronary bifurcation intervention is associated with increased procedural risk. The

majority of acute complications are related to the side branch occlusion. The use of glycoproteinIIb/IIIa inhibitors has been shown to decrease the risk of side branch closure in the Evaluation of

Platelet IIb/IIIa Inhibitor for Stenting (EPISTENT) trial using abciximab.[45]

Therefore, the use

of glycoprotein IIbIIIa inhibitors is encouraged during coronary bifurcation interventions.


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Special Stents Designed for Bifurcational Intervention

Many new bifurcation specific stents have been developed for safer use in coronary bifurcationlesions. None of these stents are approved in the USA. Some of these stents are combined with

delivery systems that allow permanent access to the side branch. This approach can potentially

decrease procedural time and reduce the risk of the side branch occlusion. Bifurcated stents, suchas BRAD XT Carina (Figure 6), new intravascular rigid flex-Side Royal and AVE stents, have

been studied in a small number of patients.[46]

In France, the DBS stent (Cordis) has been

implanted in 34 patients with a procedural success rate of 94% and stent restenosis rate of33%.

[38]Recently, several manufacturers have designed stents with delivery systems that allow

simultaneous stenting of the main and side branch ostium with a single stent. Main branch stent

can be deployed while maintaining access to the side branch with a bifurcated balloon. However,

these stents are not drug eluting and have high risk for stent restenosis. The earliest trial usingSLK-View stents (Advanced Stent Technologies, Inc. CA, USA) has been promising in eight

patients.[47]

The SLK-view stent is a scaffolding device incorporating a side aperture that allows

access to the side branch of a bifurcation lesion after stenting of the main branch. Ease of

deliverability of this stent with 100% successful side branch access was confirmed in a largertrial of 81 patients with an acceptable 6-month restenosis rate of 37.7%.[48]

A new bifurcation-

specific Multi-Link Frontier stent (Guidant Corp.) has been successfully tested in a small trial of105 patients.

[49]This stent allows stenting of the main branch and the side branch ostium

simultaneously with a single stent. The success rate was lower in comparison to SLK-view stent

at 91% with a higher overall restenosis rate of 44.8%. Successful delivery of this stent using

radial approach has been reported in a small number of patients.[50]

A similar stent-deliverysystem, the AST petal-side access bifurcation stent (Advanced Stent Technology, CA, USA), has

been tested in animal models[51]

and successfully implanted in a small trial of 13 patients.[52]

A

high stent restenosis rate using these bifurcation specific stents has lead to the design of

dedicated bifurcation-specific DES. Devax AXXESS DES is an example of this new design.This stent is a nitinol-based stent with a biodegradable polymer and a drug called Biolimus A 9.

Preliminary data on this stent from AXXESS plus a trial in 139 patients that was presented at

meetings is encouraging in reducing in-stent restenosis rate. However, at this time, long-term

safety data and larger randomized trials are needed before these stents can be approved forroutine use.


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Figure 6.

An example of bifurcated XT stent.

Summary & Conclusions

Coronary artery bifurcation lesion intervention is challenging with higher risk for stentthrombosis, stent restenosis and procedural complications. With the availability of DES,

coronary artery bifurcation interventions are increasing in numbers. A therapeutic algorithm

based on the newly proposed simplified classification is presented in this manuscript with theaim of guiding the interventional cardiologist to a better selection of a particular technique for a

given bifurcation lesion. In general, one stent should be used if possible. However, bifurcation

lesions involving both ostia (B2 lesions) are at high risk for side branch closure. Therefore, othercomplex techniques such as two-stent techniques may be the preferred approach in this setting in

order to reduce the rate of acute complications. There is no consensus statement about using

specific techniques for a given bifurcation lesions requiring two stents. The choice of two-stent

technique remains at the discretion of interventional cardiologist depending on expertise and

lesion anatomy.

Expert Commentary

Coronary intervention in the setting of bifurcation lesions is challenging. There are no clear

consensus statements with regards to different techniques in the treatment of coronary

bifurcation lesions. With a recent introduction of a simplified classification of coronarybifurcation lesions and techniques,

[17]communication and the choice of technique for a given


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bifurcation can be made easier. There is no long-term advantage in using two stents versus one

stent in a bifurcation lesion. Therefore, bifurcation lesions without side branch involvement

should be treated by using one stent. The choice of different bifurcation techniques in lesionswith the involvement of both ostia (B2) remains to the discretion and expertise of the treating

interventionalist. Lesions with large proximal healthy segments are suitable for the KST. Large

randomized trials using different techniques for different types of bifurcation lesions are requiredin order to study the advantage of one technique over any others for a given bifurcation lesion.Future DES designed for coronary bifurcation lesions may improve the procedural outcome.

Five-year View

There are many recent advances in the design of new DES and in the design of bifurcation

specific stents that can dramatically change our approach to the bifurcation stenting. Stents with

side branch access can significantly reduce the risk of side branch occlusion. Newly designedbifurcation-specific DES will soon be available with the potential to reduce stent restenosis rate.

New steerable wires, lower profile balloons and stents are in development for better side branch

access. Based on rapid advancement in stent technology, we will have better treatment optionsfor coronary artery bifurcation intervention in the next 5 years.

Sidebar: Key Issues

The new simplified and clinically relevant coronary bifurcation lesion classification andtechnique will improve communication between clinicians and researchers.

Intervention in the setting of coronary bifurcation lesions remains challenging and isassociated with increased adverse outcomes.

Whenever possible, one stent should be used for the treatment of coronary arterybifurcation lesions (lesions without the side branch involvement such as 1m lesions are

best suited to one stent technique).

Coronary bifurcation lesions with a large proximal segment and involvement of bothostia are best suitable for the kissing stent technique.

Coronary bifurcation lesions with a small proximal segment and involvement of bothostia are best suitable for the T stent, the crush stent or the cullotte stent techniques.


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Future drug-eluting bifurcation-specific stents for the treatment of coronary arterybifurcation lesions will hopefully improve the procedural outcome.

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Acknowledgments

I would like to thank Dr Mehrnoosh Hashemzadeh for her support and editing of this manuscript.

Reprint Address

Mohammad Reza Movahed, Associate Professor of Medicine; Director of Coronary Care Unit;and Medical Director of Heart Transplant Program, Section of Cardiology, Department of

Medicine, University of Arizona Sarver Heart Center; and the Southern Arizona VA Health CareSystem, 1501 North Campbell Avenue, Tucson, AZ 85724. E-mail:

[email protected].

Expert Rev Cardiovasc Ther. 2008;6(2):261-274. 2008 Expert Reviews Ltd.
mailto:[email protected]:[email protected]:[email protected]

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Coronary Artery Bifurcation Lesion Classifications