Stenting of Bifurcation Lesions

Presenter Dr Virbhan BalaiModerator – Dr Vinod Sharma

Introduction

Coronary bifurcation lesions account for 15–20% of all coronary lesions that require PCI.

Bifurcation stenosis is one of the most complex coronary lesions requiring endovascular treatment.

The best approach for the management optimal procedural outcomes and long-term success rates is still debated.

Coronary Artery Bifurcation Lesion Intervention: A Challenge

Coronary artery bifurcation lesions pose a major challenge for interventional cardiologists.

PCI for the treatment of coronary artery bifurcation lesions is associated with increased risk of complications.

Higher risk for sub acute and late stent thrombosis is of major concern.

Currently, there is no guideline to address the interventional technique in bifurcation lesion.

Coronary Artery Bifurcation Classifications

There are six major bifurcation lesion classifications described.

Four classifications were published in the era of BMS.

Similar in describing a given bifurcation lesion.

1. Sanborn's classification2. Duke classification3. Safian classification4. Lefevre classification5. Medina classification6. Movahed's classification

Summary of currently published major coronary bifurcation classifications.

Lefevre classification of bifurcation lesions.

Medina classification  

• They divided bifurcation lesions into three segments: 1. Proximal segment of the main branch 2. Side branch ostia3. 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.

• Example, lesion 1,0,1 means that proximal segment, and side branch ostia are diseased but the distal part of the main branch is free of disease.

• Easier to remember, endorsed by European Bifurcation Club.

Medina bifurcation classification.

Limitations

• Medina classification failed to include two important features of bifurcation lesions:

1. Angulation of branches (prognostic feature). 2. The size of the proximal healthy segment3. Redundancy in describing two different

lesions with similar technical decision making.

Movahed classification

• Based on a system that is composed of a single prefix to which up to four different suffixes are added.

• Prefix B (for Bifurcation lesion) to which four different suffixes can be added.

• Using suffixes that directly describe the anatomically important features of bifurcation lesions makes this classification very easy to remember.

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

• 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 Large proximal segment).• If the proximal segment is small (less than two-thirds of

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

• BL lesions are suitable for the KST, whereas BS lesions are not.

• The second suffix describes involvement of branches.

• If the ostia of both bifurcation branches are involved in the significant atherosclerotic disease process, the suffix number 2 is used.

• 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 important branch), suffix 1s is used.

• 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 branch difficult 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.

• A steep angle is significantly associated with the risk of abrupt vessel closure or side branch occlusion.

• The suffix V is given for shallow angles less than 70° (which looks like a V)

• Suffix T is given for a bifurcation with a steep angle of more than 70 degree (which looks look like a T).

• Example, a BS2T lesion is a bifurcation lesion (– B for bifurcation lesion– S for small proximal-not suitable for KST– 2 for involvement of both ostia– T for steep angulation of the branches.

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 was successfully treated using the kissing stent technique.

• Optional suffixes for other high-risk features • LM was used for left main• CA for calcium • 'TO' (for total occlusion) • 'TR' (for thrombus-containing lesion).

• BS2T-LM-CA-TR lesion. • 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.

Interventional Techniques in the Treatment of Bifurcation Lesions

• 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' (for Across)• If the stent is placed in the side branch first, it is called

S (S for Side branch).

• The most common bifurcation techniques with regards to stenting have been recently classified into six categories:

1. The one-stent technique (OST) 2. The stent with balloon technique (SBT)3. The KST 4. The T stent technique (TST) 5. The CRT6. The cullotte stent technique (CUT)

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 is KST (with regards to stent restenosis).

• Earlier trials 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%).

• Using two-stent techniques in the era of DES did not improve re stenosis rate.

• Apart from the KST in two large trials, other two-stent techniques have not been superior to OSTs.

• Restenosis usually depends on the disease burden of the side branch.

• In the Nordic study, the presence of over 50% lesions in the side branch was associated with a re stenosis rate of 11-19%, whereas less than 50% side branch disease was associated with an in-stent re stenosis rate of 4.6-5%.

• The risk of sub acute stent thrombosis has been higher using two-stent techniques in the majority of trials.

• Provisional side branch stenting in B2 lesions (both ostia are diseased) poses a high risk for side branch occlusion and increases procedural complication rate.

• The risk of side branch occlusion in B2 lesions can be as high as 65% depending on the side branch angle.

• Two-stent techniques offer safer access to both diseased branches in the high-risk lesions.

• For easier advancement of two stents in the bifurcation lesions, balloon pre dilation is recommended before stenting.

• Any bifurcation intervention poses a high risk for acute side branch occlusion.

• 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

• One-stent Technique• The OST is based on a simple technique using

one stent. • This is the best technique in bifurcation lesions

with a small side branch that can be ignored. • 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.

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.

• Also known as V stenting.• The major advantage of this technique is the ability to

maintain access to both branches at all times. • The occurrence of an edge dissection or the presence of

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

• The subacute stent thrombosis rate for 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.

• Steep angulations may cause difficulty in advancing two stents simultaneously, making BT lesions more risky with this approach.

• It is important to perform final kissing inflation of both stents at a low pressure for optimal stent deployment.

• The sequence of this technique is as follows:1. First, both stents will be deployed at a low

pressure (6-8 atmospheres). 2. 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 low pressure again at the end of the procedure.

Drawback

• Proximal edge dissection- could be difficult to treat.

• A long proximal disease segment may require initial simple stenting of the proximal segment in order to avoid creating a long carina.

• Requiring a large at least 7 Fr sheath size in order to advance two stents simultaneously.

T Stent Technique

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

'classic T technique and there are many different variations. • Pullback technique is a easiest and safest approach, here 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 stent mal position 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 branch stent 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 stent struts 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 branch requires additional stenting.

• The loss of direct side branch access after the main branch stenting is a major 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.

Crush Stent Technique

• The CRT, pioneered by Colombo et al.• Lost enthusiasm due to a high rate of sub acute

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

• Consists of advancing two stents simultaneously into both bifurcation branches.

• The proximal segment 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.

• If after the one-stent technique the side branch ostium has significant lesion despite balloon angioplasty, reverse crush technique can 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 branch and

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. • At the end of the procedure, the side branch will be rewired and final simultaneous

kissing balloon inflation is performed.• The main advantage of this technique is that it is compatible with a 6 Fr size system.

Drawbacks

1. Difficult to rewire the side branch in steep angulations such as T lesions.

2. Sub acute stent thrombosis and side branch restenosis rates high.

3. Technically challenging, since rewiring of three stent layers could be difficult.

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, is successfully utilized clinically.

• This technique utilizes an angioplasty balloon first (as opposed 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 stent layer 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%.• Furthermore, this modification adds 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 the disadvantage 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‘.• Was associated with high restenosis rates in the past. • It is gaining popularity in the era of DES.• This technique is suitable for

1. T or V lesions when both ostia of the bifurcation branches are diseased.

2. The lesions when the size of the side and main branches are similar.

3. In case of an unsatisfactory side branch result after main branch stenting using BST, the CUT.

• 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 the previously stented segment in the other branch.

• Final simultaneous kissing balloon inflation should be performed in order to expand stent struts.

Approach to the Treatment of Bifurcation Lesions

• 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.

• True bifurcation lesion → ? importance of the side branch vessel size. • If the side branch vessel is small ( ≤ 2-2.25 mm) or supplies small

territory, the lesion should be classified as BN (non significant bifurcation).

• In this case, the side branch should be ignored and stenting of the main vessel should be performed using the OST.

An algorithmic approach for the treatment of bifurcation lesion.

• 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 should reconsider 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 low pressure in the main branch before ostial side branch stenting.

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 compromised after main branch stenting.

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

The CRT is technically more challenging in angulated lesions and is associated with increased adverse outcome in these lesions.

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 is used, the pullback technique, also known as the mini crush technique, would be a better choice in order to avoid missing the side branch ostium.

Summary of Advantages and Disadvantages of Different Bifurcation Interventional Techniques

Other Technical Aspects of Bifurcation Intervention

• Wiring TechniqueIt 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

wire at 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.

There are 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 branch intervention.

This recommendation is based on many trials indicating improvement in the long-term outcome using this technque.

The superiority of final kissing balloon angioplasty has been clearly demonstrated in many trials using the CRT.

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 balloons during 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 pressure should 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 pressure sequentially 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 glycoprotein IIb/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.

Therefore, the use of glycoprotein IIbIIIa inhibitors is encouraged during coronary bifurcation interventions

Special Stents Designed for Bifurcational Intervention

Many new bifurcation specific stents have been developed for safer use in coronary bifurcation lesions.

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 XT stent.

Tryton™ side-branch stent.

Summary & Conclusions

Coronary artery bifurcation lesion intervention is challenging with higher risk for stent thrombosis, stent restenosis and procedural complications.

With the availability of DES, coronary artery bifurcation interventions are increasing in numbers.

In general, one stent should be used if possible.

Bifurcation lesions involving both ostia (B2 lesions) are at high risk for side branch closure.

Other complex techniques such as two-stent techniques may be the preferred approach in this setting in order to reduce the rate of acute complications.

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.

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