8 Bifurcation Stenosis Percutaneous Coronary Interventions
Treating bifurcation lesions involves weighing the risk of side-branch closure and the need for additional stent, sometimes requiring complex techniques. The approach to bifurcation lesions is based on the angiographic configuration of the lesion(s) in the main branch and the side branch. Significant disease (>50% stenosis) in the ostium of the side branch increases the likelihood of side-branch closure as well as the restenosis rate after percutaneous coronary intervention (PCI). Several classification schemes have been developed; these are summarized in Figure 8-1. Side branches at low risk (not likely to be compromised) include prestenosis branches, poststenosis branches, and those branches that do not straddle a stenosis. PCI across an uninvolved side branch carries a less than 1% risk of occlusion. The requirement for side-branch protection for the three side-branch locations above (prestenosis, poststenosis, not straddling a stenosis) is minimal, as the technical difficulty of approaching the target branch is also low.
Bifurcation lesions that are at high risk for side-branch closure are side branches that straddle the stenosis of the main vessel and side branches with ostial stenosis. The technical difficulty of treating these stenoses increases with the severity of side-branch narrowing. The risk of side-branch closure with an ostial narrowing approaches 15%.
When there is an equal distribution of coronary plaque across a bifurcation stenosis, simultaneous balloon angioplasty of both branches should be considered to maintain vessel patency, followed by one-stent or two-stent PCI. In some cases, operators can choose to debulk the involved side branch with rotational atherectomy or cutting balloon angioplasty to decrease the likelihood of side-branch closure with main-branch PCI.
Classification of Bifurcation Lesions
The treatment of bifurcations depends on the distribution of disease, ostial involvement, and size of branch from the parent vessel. The most commonly used classification system is the Medina (Fig. 8-2), which assigns a 0 or 1 to the presence or absence of disease in the proximal segment, distal segment, and branch vessel. The major objection to this scheme is that it does not account for angulation, which significantly contributes to procedure success rates. Another schema is depicted in Figure 8-3.
Figure 8-3 Schematic representation of lesion and side-branch involvement. A, B, and C represent parent vessel involvement with no disease located in the side-branch vessel. D, E, and F represent parent and side-branch involvement with more than 50% ostial stenosis in the side branch.
(Adapted from Freed M, Grines C. Manual of interventional cardiology. Birmingham, MI: Physicians’ Press, 1992.)
Choosing Between One-Stent (Provisional) and Two-Stent Techniques
Even in the drug-eluting stent (DES) era, several large studies including meta-analyses have shown that one-stent techniques are as good, if not better, compared to two-stent techniques for late outcomes. Trials using DES for bifurcation stenting have shown higher incidences of subacute thrombosis with two stent techniques. It is unclear what the risk-benefit ratio is of having more metal, drug, and polymer at the bifurcation site.
There are no specific guidelines established in choosing a one-stent versus a two-stent technique for a bifurcation lesion. The decision is highly dependent on its anatomic configuration and operator preference and expertise. The operator must make a judgment based on the importance of the side branch (i.e., amount of myocardium at risk), the risk of side-branch closure, and the risk of two-stent PCI. In addition to disease burden in the ostium of the side branch, angulation of the side branch is another important factor since steep angulation makes access to the side branch more difficult after main-branch PCI and is associated with higher procedural complications.
The general consensus is that for bifurcation lesions without high risk features, the default approach of one-stent PCI with provisional angioplasty + stent is appropriate. Hemodynamic assessment of the jailed side branch can also be considered because angiographic severity may not always correlate with physiologic significance, especially for ostial lesions. For bifurcation lesions with high-risk features as described above, two-stent techniques may be safer due to protection and treatment of the side-branch vessel.
General Approach to Bifurcation Lesions
Guide Catheter Selection
A 7 F or 8 F guiding catheter should be selected if the operator anticipates using two stents. A 6 F guiding catheter can accommodate only two monorail balloon catheters, whereas an 8 F guiding catheter can accommodate two stent systems as well as other large-diameter PCI devices such as the Rotablator or the Flextome Cutting Balloon. The maximum Rotablator burr that can be used with a 6 F guiding catheter is 1.5 mm. It may be prudent to “upsize” guiding catheters when approaching any bifurcation lesion so that all options remain available if trouble occurs during the procedure.
Guidewire Technique
To protect the side branch, two guidewires are placed, one in the side branch and one in the main vessel. The order of inflation is relatively unimportant. Wire markers or using two different wire types is helpful to reduce confusion during balloon inflations and wire repositioning. When using a two-guidewire system, the guidewires may become entangled after multiple wire manipulations. Efforts should be made to avoid guidewire entanglement, which will prevent advancement of the balloon and may result in failure to recross the stenosis.
Balloon Catheter Selection and Inflation Strategies
Standard balloon catheters can be used, but different balloon sizes may be required for each branch (Table 8-1). Sequential balloon inflations or simultaneous “kissing” balloon inflations can be performed with elimination of plaque shifting being the advantage of the latter. It is important to make sure that the main vessel can accommodate both balloon diameters when performing kissing balloon inflations (proximal vessel should be at least two thirds of the combined balloon diameters). After stent placement in the main branch and the side branch, simultaneous kissing balloon inflations are critical to restore the circular and fully expanded stent to each lumen. Failure to perform final kissing balloon inflation will likely lead to restenosis.
Table 8-1 Approach to Bifurcation Stenosis
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| Approach | Advantages | Disadvantages |
|---|---|---|
| Guide Catheter Selection | ||
| Two-guide catheters | Separated devices | Two artery punctures |
| Large variety of catheters | Two-catheter manipulation | |
| Long procedure time | ||
| One-guide catheter | One arterial puncture | |
| Fewer catheter manipulations, low risk of ostial trauma | ||
| Reduced procedure time | ||