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The 'Hybrid' Approach: The Key to CTO Crossing Success
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Most attempts to intervene on coronary chronic total occlusions fail because the wire cannot cross the occlusion. Three main strategies can be used to cross a CTO: antegrade wire escalation, antegrade dissection/re-entry and retrograde. There is, however, confusion about when and how to use each of these techniques in everyday practice.
Emmanouil S.
Brilakis
To provide guidance on this important practical question, an expert consensus algorithm was developed by 13 experienced CTO operators during a workshop that took place in Bellingham, Wash., in January 2011. The reader is referred to the full document (see reference at the end of the article) for a complete discussion; however, a summary of the algorithm and recommendations follows (Figure).
Step 1: Dual Injection
The first and arguably most important step in trying to cross a coronary CTO is to perform dual coronary injection (except in cases in which only ipsilateral collaterals exist). Dual injection allows good visualization of both the proximal and distal vessel, as well as the collateral circulation, allowing selection of the most suitable initial crossing technique. It also clarifies the location of the guidewire(s) during crossing attempts. Routine performance of dual injection is probably the simplest and most important step to increase the success rates of CTO PCI.
Step 2: Assessment of CTO Characteristics
In-depth review of the angiographic images is critical and should ideally be done before the procedure. Four parameters are assessed: the presence of a clear-cut or ambiguous proximal cap; the length of the occlusion; the distal-to-the-CTO vessel size and presence of bifurcations; and the location and size of collaterals that could be used for the CTO retrograde approach. In general, lack of a well-defined proximal cap, a long lesion length, a diffusely diseased distal vessel and the availability of good collaterals favor a primary retrograde approach.
Step 3: Assessment of CTO Length
In CTOs in which antegrade crossing is attempted, short CTO lesions (<20 mm) are usually best approached with antegrade wiring, whereas in long (≥20 mm) CTOs, upfront use of a subintimal dissection/re-entry technique is preferred (because it is nearly certain that wire-based crossing attempts will result in subintimal wire entry).
Figure. Algorithmic approach to crossing coronary chronic total occlusions
Source: Brilakis ES.
Step 4: Antegrade Wiring
Antegrade wire escalation refers to the use of guidewires of increasing stiffness to cross a CTO. In the past, a “gradual” escalation was performed: starting with a workhorse guidewire and then increasing to a Miracle 3, 6, 9 (Asahi Intecc) and eventually a Confianza Pro 12 guidewire (Asahi Intecc). Currently, however, a “fast” escalation is favored from a tapered-tip polymer jacketed guidewire (Fielder XT, Asahi Intecc) to either a stiff polymer-jacketed wire (Pilot 200, Abbott Vascular) when the course of the CTO is uncertain or a stiff-tapered tip guidewire (Confianza Pro 12) in cases where the course of the CTO is well understood. Streamlined use of a relatively small array of guidewires can simplify clinical decisions and inventory management.
Step 5: Antegrade Dissection and Re-Entry
For long lesions approached in the antegrade direction, upfront use of a dissection/re-entry strategy is recommended. Dissection can be achieved either by advancing a “knuckle” formed at the tip of a polymer jacketed guidewire (such as the Fielder XT or the Pilot 200) or by using the CrossBoss catheter (BridgePoint Medical). Antegrade dissection minimizes the risk for perforation (by the blunt guidewire loop or by the CrossBoss catheter tip) and allows rapid crossing of long occlusion segments. Re-entry can be achieved using a stiff polymer jacketed or tapered tip guidewire with a sharp distal bend, or by using the Stingray system (BridgePoint Medical), which is a specially designed re-entry balloon catheter with two ports located in diametrically opposite directions.
Step 6: Retrograde
Retrograde CTO PCI is a major component of a contemporary coronary CTO program and was covered in detail in the May/June CTO Corner column. The retrograde approach can be used upfront (primary retrograde, as described in step 2) or after antegrade crossing attempts fail, and it enables high procedural success rates. Retrograde wire crossing can occur by advancing the retrograde guidewire into the proximal true lumen (retrograde true lumen puncture) by antegrade wiring toward a retrogradely placed guidewire into the distal true lumen (“just marker” technique) or by using one of the dissection/re-entry techniques, such as controlled antegrade and retrograde tracking (CART), or, more commonly, the reverse CART technique.
Step 7: Change
The “hybrid” approach to CTO PCI is defined as the approach that “focuses on opening the occluded vessel, using all feasible techniques in the most safe, effective and efficient way.” This is a fancy way to say: “When one approach fails, try something else!” For example, if antegrade wire crossing fails, then antegrade dissection/re-entry should be tried, and if this fails too, retrograde crossing should be attempted (if, of course, appropriate collaterals exist).
Conclusion
The (rapid) change of strategies is at the heart of the proposed algorithm. Every CTO is different and as a result may require different strategies for success. Instead of persevering with a strategy that fails, it may be best to switch to a different strategy. At the same time, the operator should not change too early, but instead invest enough effort in the utilized strategy to maximize its chance for success. What constitutes an “adequate effort” varies from lesion to lesion and operator to operator, and is best determined with increased CTO PCI experience.
Full application of the CTO crossing algorithm requires training and experience with all types of CTO crossing techniques, and hence may not be fully applicable by all operators during their learning curves. It does provide, however, a framework that can facilitate building and applying a comprehensive CTO PCI skill set.
Emmanouil S. Brilakis, MD, PhD, is the director of the cardiac catheterization laboratory at the VA North Texas Health Care System, Dallas, and is associate professor of medicine at the University of Texas Southwestern Medical Center, Dallas. He is also a Cardiology Today Intervention Editorial Board member. He can be reached at Dallas VA Medical Center (111A), 4500 S. Lancaster Road, Dallas, TX 75216; email: esbrilakis@yahoo.com.
Disclosure: Brilakis has received speaker honoraria from BridgePoint Medical, St. Jude Medical and Terumo; research support from Guerbet; and his spouse is an employee of Medtronic.