Together with calcified lesions, saphenous vein grafts, chronic total occlusions and unprotected left main lesions, bifurcation lesions are complex lesions that remain among the outstanding challenges of treatment with percutaneous coronary intervention. Bifurcation lesions are associated with increased rates of procedural complications, restenosis and adverse events than lesions in the body of the vessel. The introduction of drug-eluting stents for the treatment of bifurcation lesions has dramatically decreased restenosis rates, especially in patients suffering from diabetes.
However, abrupt side branch closure, side branch ostial restenosis and stent thrombosis remain areas where further improvement is needed. Although a provisional T-stent strategy is most often used when side branch stenting is required, there are true bifurcation lesions where the selected use of more complex bifurcation approaches such as the crush technique, T-stenting or the culotte technique seem appropriate, particularly when the main branch and side branch are larger vessels with more diffuse side branch disease.
The major challenge with any technique is to ensure that the side branch is protected and there is a satisfactory final result. Many technical questions rise in trying to ensure this outcome and lower the risk of intra- and post-procedural complications such as side branch closure and restenosis, stent thrombosis, dissection and fracture of a jailed wire: how can difficult side branch access be solved?
How can unfavourable side branch anatomy be re-wired after main vessel stent placement? How can fracture of a jailed wire be avoided? Is side-strut dilation beneficial? A higher risk of subacute and late stent thrombosis is a major concern as well.
A significant side branch is a branch that you do not want to lose in the global context of a particular patient symptoms, location of ischaemia, viability, collateralising vessel, left ventricular function, etc. The Medina classification is simple and practical; however, it does not include the description of angulation of branches and the size of the proximal healthy segment, as is the case in the classifications proposed by Movahed et al. Nonetheless, the Medina classification has gained the highest popularity both in research and in clinical practice.
Coronary bifurcations are a unique and heterogeneous collection of anatomical variations. Different treatment strategies are employed based on plaque burden and the location and angulation of the bifurcated lesion. There have been many randomised studies see Table 1 and analyses of non-randomised trials and registries 30—33 published comparing different techniques and stents for the treatment of bifurcation lesions. Two meta-analyses of randomised controlled trials comparing a simple versus a complex strategy in the treatment of bifurcation lesions using DES revealed that a provisional strategy was associated with a reduction in myocardial infarction and a non-significant reduction in stent thrombosis rates.
At present, a one-stent technique — stenting the main branch with a DES and using a provisional side branch technique side branch stenting or ballooning — seems to be the prevailing approach. When the side branch arises at a shallow angle, other two-stent techniques crush, culotte or kissing stent can be considered. Sharma et al. The best intervention for a bifurcation lesion is to stent the main branch without compromising any side branch. However, low-pressure balloon inflation of the side branch can help to prevent plaque shifting from the main branch lesion in high-risk situations.
The advantage of this strategy is that the atherosclerotic material in the main branch is re-arranged to a large degree and further main branch stenting may not cause further plaque shifting; it will also help to avoid the need for subsequent side branch dilation through the side strut. One has to be aware of the potential for rupture of a plaque in the proximal part of the side branch, which would lead to the need for side branch stenting.
To avoid this situation, it is important that balloon is not oversized and is inflated to a low pressure. The combination of plaque distribution and vessel anatomy determines scenarios in which side branch wiring requires great experience and technical skill.
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Successful difficult side branch access wiring can be achieved with use of an appropriate guidewire with an appropriately shaped tip curvature. A wide angle between the proximal main vessel and side branch together with marked side branch ostial disease make wiring especially challenging.
Step-by-step manual for planning and performing bifurcation PCI: a resource-tailored approach
A useful solution is to shape the tip with a wide smooth bend or with a double bend and to use a pullback wiring technique if antegrade technique does not work. With this system, the guidewire may be directed towards the side branch after deflection of the catheter tip and then advanced in the side branch over the strong support of the catheter.
A typical situation is a bifurcation with a large plaque burden in both the main vessel and side branch and a wide take-off angle. This technique is not advisable as it may cause plaque and carina shift, ultimately resulting in side branch occlusion. In the optimal scenario, gentle pre-dilatation of the proximal main vessel may create enough space in the main vessel and change the angle for successful advancement of a bent wire towards the side branch.
This specific review will be devoted to review those concepts as well as clinical evidences to support them. The treatment of bifurcation lesions is still in some ways an art form, as Dr. Serruys said. This review is not to reiterate all the steps in coronary bifurcation stenting. Comprehensive review of coronary bifurcation lesion was already published in the supplement V of EuroIntervention in , which was organized and edited by European Bifurcation Club EBC.
For so many years we have been focused on the optimization of SB, but clinical events such as target lesion revascularization TLR are mostly on the main vessel. Bifurcation lesion consists of MV and SB. I prefer, however, to call them as parent vessel PV and main branch MB , just like a tree can be divided into trunk and branches Figure 1. The most important concept to understand a bifurcation lesion is the relationship between the sizes of these vessels. The first theory that can be applied to explain the relationship was Murray's law.
IVUS of coronary bifurcation lesion.
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A Carina white arrow is spared of atherosclerotic plaque. Koo BK. Which was calculated mathematically as the physiological principle of minimum work. This theory was proven in normal and diseased coronary bifurcations by intravascular ultrasonography IVUS study in our group. The first important practical implication of this theory is that the diameter difference of PV and MB is dependent on the size of SB. This is why we need to consider the routine proximal optimization technique in the bifurcation lesion with a large SB. If the Murray's law is correct, the sum of balloon cross-sectional areas of 2 branches are larger than the cross-sectional area of PV.
Kissing ballooning would be better to be conservative with moderate pressure to avoid possible PV injury, according to this theory. One of the popular methods to calculate the size of PV is Finet's law. This equation is derived from the quantitative analysis of coronary angiography in normal coronary bifurcations. Unfortunately, the relationship is quite variable according to the vessel size.
As a summary, understanding the relationship of different vessel sizes in PV, MB, and SB is the key to optimal final kissing ballooning and proximal optimization, which will be reviewed in more detail below. Considering the common variations of vessel size, IVUS examination is required for the optimal result. IVUS guidance was reportedly associated with a better cardiovascular outcome after coronary bifurcation stenting. The occlusion of SB after MV stenting is one of the most common complications during bifurcation stenting. Instead, the carina structure itself can be shifted to SB, which can be the major cause SB compromise Figure 2.
The first paper suggesting the critical role of carina shift was based on the complex angiographic analysis of coronary bifurcation lesion. Of note, the predicted percent diameter stenosis of SB ostium with full carina shifting is calculated as a cosine of bifurcation angle, which means more carina shift with narrower bifurcation angle. This result suggested the initial assumption that the carina shift is the major mechanism, but this is indirect morphological evidence.
So it seems evident that the carina shift is a major contributor of anatomical SB ostial compromise. Functional study, however, showed an opposite result. It has been well-known that the anatomical significance was not well correlated with the functional significance measure by FFR in SB after MV stenting. Angiographically the carina shift looks exaggerated by the negative shadow of MV stent across SB ostium.
A large bifurcation stenting registry data also confirmed the importance of plaque shift, again. Notably, this study found that significant stenosis in ostial SB, significant proximal MV disease, and acute coronary syndrome were independent predictors of SB compromise, which suggests that the plaque shift is the major mechanism. Similar finding was noted from computed tomography angiography study. As a summary, the anatomical compromise of SB after MV stenting is not functionally so significant than it looks, because it is mostly explained by carina shift, which is not the major cause of functional compromise.
The plaque shift superimposed on carina shift appeared to be necessary to cause a hemodynamically significant SB stenosis. The plaque is shifted mostly from the proximal MV, which explains that the plaque burden of proximal MV is the significant risk factor of SB functional compromise or occlusion. This concept is practically important to avoid SB compromise after MV stenting, which will be discussed below.
The first step of MV stenting is the selection of stent with optimal size to distal vessel diameter I call it distal optimization.
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The diameter of the vessel is better to be assessed by IVUS, for angiography is frequently misleading. When the distal reference vessel is disease free, the stent size should be the same size of vessel size. When the distal reference vessel is abundant in atherosclerotic plaque, common knowledge is to select the average of lumen and vessel diameters. In the reference segment is calcified, stent size should be smaller to avoid distal stent edge dissection.
Then the stent should be more expanded in the PV. The proximal optimization technique POT is post-dilating the MV stent just proximal to the carina, with a short non-compliant balloon sized for the reference diameter of PV. Originally it was invented to facilitate the passage of a wire and a balloon into the distal struts on MV stent. Interestingly, when final kissing ballooning was performed, there was no benefit of POT. Maybe it is because the PV is already fully expanded by 2 balloons used for kissing technique. The risk of SB occlusion during the procedure is the major cause of the complexity of coronary bifurcation stenting.
The maneuvers to avoid SB occlusion may be the cause of suboptimal MV stent expansion, which may be the major cause of stent thrombosis and restenosis. The SB compromise was reported to be associated with the increased risk of peri-procedural cardiac mortality and myocardial infarction MI. There have been several studies for the predictors of SB occlusion, 29 , 30 but most of them were small studies. Jailed wire technique, however, is the significantly predictor of reopening the occluded SB.
Unfortunately, this study could not catch any significant procedural predictor we can apply in the real practice. Our IVUS study in the coronary bifurcation lesion showed the stent expansion in MB is significantly associated with carina shift, and the stent expansion in PV was associated with plaque shift.
The proximal and distal optimization technique can be a good solution for the optimal stent expansion avoiding SB compromise. My personal recommendations based those studies are as follows Figure 3 ; 1 start with the wiring the MV and a large SB. Predilate the SB with severe ostial stenosis.
Wire prolapse technique is useful to avoid wire undermining of the stent. B My personal recommendation.
POT is performed after SB rewiring with wire prolapse technique. The clinical, angiographic, and procedural characteristics of the 2 groups are shown in Baseline Clinical Characteristics in the Total and Propensity Score-Matched Populations. MLD, minimal luminal diameter; RD, reference diameter.
Other abbreviations as in Table 2. The incidence of both SB dissection 1. SB stent implantation was more frequently performed in the predilation group than in the non-predilation group The angiographic success rates, overall Other abbreviations as in Tables 1—3. The risk of MACE 9. Kaplan-Meier curves for major adverse cardiac events in the side branch predilation group vs. A Total population. B Propensity score-matched population. Other abbreviations as in Tables 1—4.
Comparison of abrupt side branch occlusion in the subgroups. We additionally analyzed the acute angiographic and procedural outcomes, and long-term clinical outcomes in patients with LMT bifurcation. Baseline, angiographic and QCA data showed that the rate of using SB protection wire was higher in the predilation group. Percutaneous coronary intervention for coronary bifurcation disease: 11th consensus document from the European Bifurcation Club. EuroIntervention ; 38— To date, only a few studies of the effects of SB predilation have been done.
Pan et al showed improved TIMI flow after MB stenting and decreased additional SB treatment in patients who were treated with SB predilation, but the overall clinical outcomes were comparable with those who did not receive SB predilation. Assessment of side branch predilation before a provisional T-stent strategy for bifurcation lesions: A randomized trial.
Am Heart J ; — Impact on clinical outcomes of predilatation using the kissing-balloon technique for crossover stenting in true coronary bifurcation lesions. J Invasive Cardiol ; — Influence of balloon size on initial success, acute complications, and restenosis after percutaneous transluminal coronary angioplasty: A prospective randomized study. Dissection following balloon angioplasty: Predictive possibilities using pre-interventional intravascular ultrasonography.
Z Kardiol ; — in German. Lancet ; — Comparison of the first- and second-generation limus-eluting stents for bifurcation lesions from a Korean multicenter registry. Circ J ; — First- versus second-generation drug-eluting stents for the treatment of coronary bifurcations. Cardiovasc Revascularization Med ; — The effects of side branch predilation during provisional stenting of coronary bifurcation lesions: A double-blind randomized controlled trial.
Res Cardiovasc Med ; 5: 1—6. Routine SB predilation is not recommended in bifurcation interventions, but if SB compromise is anticipated after MV stenting, it should be considered. Factors favoring SB predilation include the presence of severe SB ostial stenosis, suboptimal SB flow after wiring, extensive calcification and extensive SB disease extending beyond the ostium. Preintervention angiographic and intravascular ultrasound predictors for side branch compromise after a single-stent crossover technique. Am J Cardiol ; — Carina shift versus plaque shift for aggravation of side branch ostial stenosis in bifurcation lesions: Volumetric intravascular ultrasound analysis of both branches.
Circ Cardiovasc Interv ; 5: — Hemodynamic impact of changes in bifurcation geometry after single-stent cross-over technique assessed by intravascular ultrasound and fractional flow reserve. Catheter Cardiovasc Interv ; — Our results should be appraised with consideration of the following limitations. This study was based on a retrospective registry and was not randomized, and therefore selection bias and potential confounding factors might have significantly affected the results. Although we performed rigorous propensity score-matching, there is possibility that the SB predilation group had unmeasured variables that made operators to perform predilation and it is difficult to predict how residual confounding would affect clinical outcomes.
Neither treatment strategy nor stenting technique was prespecified.