Highlights of the Scottsdale Interventional Forum 2014, How-to Symposiums: Advances in Chronic Total Occlusion Therapy

Introduction 

The tenth annual Scottsdale Interventional Forum (SIF), which took place in Scottsdale, Arizona from March 5-8, 2014, brought together some of the leading experts in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) to review some of the current concepts and advances in this field. The topics discussed included review of the diagnostic coronary angiogram in the context of CTO-PCI; strategic approaches to CTO-PCI; the CTO toolbox; and review of antegrade and retrograde techniques. 

Reviewing the Angiogram and Planning a Strategy 

One of the most important steps in approaching a CTO case is having a well thought-out strategy. Planning is the key to efficiency and success. The case plan begins with taking the diagnostic angiogram correctly. It is vital to have “set-up shots” that allow visualization of the collaterals without panning and often involves the use of dual-catheter injections and low magnification. The use of biplane angiography, imaging at 7.5 frames/second and avoidance of ad hoc CTO-PCI allow for minimizing radiation dose to the patient.  

Four main components to review in the angiogram include: 

1. Proximal cap characteristics. A non-ambiguous cap is defined as one in which the operator is confident of the location of the proximal cap. This confidence allows for advancing a penetration wire within the architecture of the vessel. Intravascular ultrasound into a side branch can help clarify the location of the proximal cap.  
2. Length of the total occlusion as determined by dual-catheter angiography (<20 mm or >20 mm). 
3. Quality of the interventional collaterals and their usability by the operator based on his/her skillset. Interventional collaterals can be septals; epicardial vessels or vein grafts. 
4. Distal cap location (whether it is located at a bifurcation) and the quality of the distal vessel, especially the presence of diffuse disease and calcium (both factors that make reentry difficult). 

Another point emphasized by the experts is the operator “mindset.” The experts de-emphasize a dogmatic approach of either an antegrade or a retrograde attempt, but rather a fluid approach harmonizing these strategies in the so called “hybrid approach” (Figure 1). Using the current skillsets and devices, a success rate of >90% is attainable. This cannot be achieved by a “poke and hope” approach or just having some of the skillsets (ie, antegrade wire based or only retrograde dissection reentry), but rather by a diligent effort to acquire all of the skillsets needed to achieve a consistently high level of success.¹  

The CTO Toolbox in 2014 

The parsimonious CTO tool box involves a capital investment of approximately $30,000. This allows the operator to have all the tools needed to safely perform CTO-PCI. Included are infrequently used (but potentially lifesaving) devices like coils and other equipment needed to manage a complication and other infrequently encountered situations such as need for a laser or a snare.   

Sheaths and guiding catheters. Eight Fr long sheaths are the preferred sheaths used for CTO-PCI, because they eliminate the potential issues with iliac and aortic tortuosity impeding torqueability of devices within the coronary artery. CTO-PCI can be performed either transfemorally or transradially, but requires the operator to be familiar with the limitations of each sheath size. The most common configuration is the bifemoral approach. This allows a full range of options, albeit at a slightly higher rate of access-site complications. For example, one of the most popular ways to remove or exchange equipment or wires is the “trap-balloon” technique. With this technique, short wires can be exclusively used. However, this involves the use of a balloon to trap the wire against the wall of the guide catheter. The 7 Fr sheaths allow use of the Corsair or CrossBoss (BridgePoint Medical) with a trap balloon, but will not support the Stingray balloon (BridgePoint Medical) with a trap balloon. An 8 Fr sheath enables use of real-time intravascular ultrasound guidance in conjunction with the Corsair or Stingray and a trapped balloon. 

Another access route that is gaining acceptance is the unifemoral-uniradial approach, wherein the donor vessel is cannulated with a shortened 6 Fr guide catheter and the recipient or target vessel is cannulated with an 8 Fr guiding catheter. Biradial PCI can be done, but requires a high level of competence in complex PCI with 6 Fr systems and expertise in use of anchoring techniques; Guideliner and Tornus catheters are used for additional support with this access route.  

CTO-PCI guidewires in 2014. The hybrid operators have simplified the confusing array of wires that can be used in CTO-PCI. A thorough knowledge of only 4 guidewires can enable you to perform the vast majority of procedures. Each wire has a specific role and purpose and understanding that is the key to success.  

The Fielder XT wire (Asahi Intecc) is a tapered, low tip force, polymer-jacketed guidewire used for microchannel tracking  and for purposes of traversing the subintimal space using the knuckle technique.  

The Sion (Asahi Intecc) and Fielder FC (Asahi Intecc) are non-tapered, low tip force wires, either with or without a polymer jacket. These guidewires are used exclusively for collateral crossing. Outside the United States, the Fielder XT-R and XT-A wires (Asahi Intecc) serve a similar purpose.  

The Pilot 200 (Abbott Vascular) is a non-tapered, moderately-high gram force guidewire used for complex long lesion crossing, tortuous lesions, and also for traversing the subintimal space when additional force is needed  in the knuckle technique.  

The Confianza Pro 12 (Asahi Intecc) is a tapered, high gram force, non-jacketed guidewire used for penetration and cap puncture.   

Guidewires currently not available in the United States are the Fielder XT-R/XT-A and the Gaia family of wires (Asahi Intecc). The Fielder XT-R and XT-A use the same core technology as the Sion family. The Fielder XT-R is recognized for its tip flexibility and maneuverability, collateral channel tracking, and use in severe stenosis. The Fielder XT-A is recognized for its penetration performance and maneuverability. Gaia wires are coated with a hydrophilic coating that enhances controllability and minimizes whip. Their tip loads are 1.7 gf, 3.5 gf, and 4.5 gf, respectively.

Microcatheters. There are three commonly used microcatheters in CTO-PCI: (1) the Finecross (Terumo Corporation), (2) the Corsair (Asahi Intecc), and (3) an over-the-wire balloon. Each has its advantages, and in the vast majority of cases they can be used interchangeably. The Finecross microcatheter ends distally at 1.8 Fr and has the smallest profile. It has Glide Technology with hydrophilic coating on the distal portion just before its 13 cm floppy tip. The microcatheter is composed of a stainless-steel braid. The Corsair catheter has a proprietary braiding pattern, which consists of 8 thinner wires wound with 2 larger ones. The Corsair is essential for retrograde technique, as it serves as a channel dilator. The 135 cm version of the Corsair has a role in the antegrade approach as well by virtue of its exceptional trackability and pushability in spite of a slightly larger profile. Newer versions of the Corsair catheter will be available soon.

Specific antegrade dissection reentry (ADR) equipment. Specific ADR equipment includes the CrossBoss catheter (BridgePoint Medical), the Stingray balloon (BridgePoint Medical), and the Stingray wire (BridgePoint Medical). The CrossBoss catheter tracks via “fast-spin” technique, and is equipped with a highly torqueable 2.3 Fr shaft. In addition, the CrossBoss catheter has an atraumatic rounded distal tip and is 0.014˝ guidewire compatible (over-the-wire). The Stingray balloon has a 2.9 Fr shaft profile and is compatible with a 0.014˝ guidewire and 6 Fr guide catheter. The Stingray balloon is flat in shape and has offset exit ports for the Stingray guidewire to reenter the vessel (Figure 2). The Stingray wire is a specific wire with a 0.007˝ tip for fenestration from the subintimal space into the true lumen and 0.009˝ distal segment that then becomes a 0.014˝ compatible wire. It has a premade 27˚ angulation at the tip to facilitate reentry.  

Wires for externalization and snares. Generally, any wire more than 300 mm in length can be used to help facilitate externalization. Wires specifically used are the 335 cm ViperWire Advance (CSI), the 330 cm RG3 (Asahi Intecc), and the 350 cm R350 (Vascular Solutions). Snares typically used are the EN Snare (Merit Medical Systems) and the Amplatz GooseNeck Snare (Covidien).     

Additional tools. High-speed rotational atherectomy (HSRA) is another tool required in the CTO toolbox. An undilatable lesion in the CTO segment within the true lumen or even within the subintimal space could require modification. Using a 1.25 mm burr, rotational atherectomy can be performed with differential cutting, safely in the subintimal space to problem solve in that situation. 

The Twin-Pass catheter (Vascular Solutions) is an additional support tool that may lend itself to use during CTO cases. It is a specific catheter where the distal lumen is monorail and the proximal lumen is an over-the-wire system that can be used to insert another wire. Wiring the side branch with the TwinPass catheter allows accessing the CTO with a second wire while maintaining position in the side branch. This is especially helpful when the proximal cap is at a bifurcation.  

Guide extensions like the Guideliner catheter (Vascular Solutions) or Guidezilla (Boston Scientific) are tools worth considering when developing your CTO strategy. These can avoid wire externalization into the aorta and facilitate delivery of long stents.   

The Turbo Elite (Spectranetics) peripheral laser that is useful in impenetrable proximal caps and in retrograde dissection reentry to facilitate reverse cart. It is usually set at 80 fluency/80 frequency and also used in situations where its ablative qualities can help ablate tissue to allow for completing the retrograde dissection reentry procedure.  

Complication management. Covered stents, coils, embolization particles, and fat embolization are all options to consider when confronted with complications such as a coronary artery perforation. 

Antegrade Approach  

Two major strategies with the antegrade approach include wire escalation and antegrade dissection reentry (Figure 3). Wire escalation technique involves a stepwise increase in the gram force of coronary wires until the cap is penetrated. If there is no proximal cap ambiguity, the lesion is less than 20 mm, and there is a good target, then wire escalation is favored. A soft-polymer jacketed guidewire, such as the Fielder XT, is used initially. If the Fielder XT is unable to penetrate and there is a clear path and target, then a wire with more tip force, such as the Confianza Pro 12 (Asahi Intecc), should be selected.  

Antegrade dissection reentry strategy is favored when there is no proximal cap ambiguity, good distal target visualization, and the target lesion is greater than 20 mm. The CrossBoss and StingRay (BridgePoint Medical) are the devices of choice for the ADR method. Wire-based techniques, including the knuckle wire, contrast-enhanced STAR, and LaST method, can also be used as a last resort, but reentry is less consistent with these techniques and more exquisitely controlled with the BridgePoint Medical System devices. 

Retrograde Technique: From Simple to Most Complex Collateral Crossing

Collateral crossing can be a limiting factor in even the most seemingly simple CTO interventions. Even expert CTO operators are unable to cross a collateral in 20% of the cases.⁴ Successful crossing of the collateral channel sets the stage for success during the retrograde procedure. The three major collateral channels include septals, epicardials, and bypass graft channels. Recently, with the availability of the Sion and XT-R, epicardial channel crossing has been used more frequently even in patients with intact pericardium. Septal channels, however, remain the most commonly used interventional collaterals. The success rate for crossing septals remains higher than with the use of epicardial channels. An occluded bypass graft or a failing bypass graft may be another collateral for retrograde CTO-PCI. An occluded graft can be crossed with a hydrophilic polymer-jacketed wire and the support of a Corsair catheter. It can be used as a conduit for retrograde CTO-PCI without any incremental risk of showering the distal bed with debris from the graft.  

Retrograde Conduits 

Selecting the right collateral channel hinges on optimal visualization of the collateral vessel in the best projection. When viewing septals, right anterior oblique (RAO) cranial best projects the left anterior descending to the base of the heart, while RAO caudal or RAO best project the base of the heart to the posterior descending artery. It is important to remember that septal conduits are better selected based on entry and exit angle rather than size. Septals can sometimes be wired even though they may not be visible angiographically. Also, a careful review of the diagnostic angiogram prior to proceeding with retrograde PCI is immensely helpful to prioritize the septals visualized based on the angles of entry and exit, as well as the presence of stents within the donor vessel and extent of proximal disease in the donor vessel.  

Epicardial collaterals require unique angles to project them in orthogonal views. These must be obtained to lay out the collateral throughout its course.  Unlike septals, epicardial collateral channels are never dilated because of risk of perforation, and the tortuosity of the epicardial channel frequently limits its crossability. Because guide support and wire angles into the CTO can be challenging when accessing a bypass graft channel, there may be a need to shorten guides even further than 90 cm.  

CTO Crossing 

There are a total of 4 wire combinations that can be utilized with retrograde strategy for intervention when in the CTO body (Figure 4). Successful retrograde crossing of the CTO lesion can be achieved in various approaches. The most frequent approach is the retrograde dissection reentry method, also known as the reverse CART. The second-most common approach is retrograde wire escalation. The two other rare forms of CTO crossing include the traditional CART or the kissing-wire technique. In the J-CTO registry, the retrograde approach was attempted in a significant portion of the study population (133 of 494; 26.9%), with a final procedural success rate of 75.9%. The frequency of attempts using the retrograde approach was 4.4% in the easy lesion group and 14.6% in the intermediate lesion group. Only 11 of 133 patients (8.3%) met the endpoint of successful guidewire crossing within 30 minutes in the retrograde subset compared to 62.9% of cases not requiring the retrograde approach.³ 

Conclusion 

The “Scottsdale Interventional Forum: How-to Symposium on Chronic Total Occlusion Therapy” offers the opportunity for cardiologists to learn from and connect with some of the leading experts in this field. CTO-PCI offers symptomatic relief to patients with ischemic heart disease that in the past were considered to have no real options for revascularization. However, the ability to perform CTO-PCI requires considerable experience and a skillset above and beyond that which is needed for routine PCI. Thus, a significant number of patients with CTOs and symptomatic ischemic heart disease remain medically managed.⁴ The thought leaders in this field have, over the past several years, attempted to demystify and expand CTO-PCI with a unique and easy-to-adopt approach. Thus, relevant to this year’s series of lectures was the continued emphasis of the CTO-PCI hybrid algorithm. This algorithm was highlighted and emphasized by all presenters. Overall, the hybrid approach provides a useful working and training framework for operators performing CTO-PCI and should help increase attempt and success rates and improve efficiency.⁵  

References

1. Chandrasekar B, Doucet S, Bilodeau L, et al. Complications of cardiac catheterization in the current era: a single-center experience. Catheter Cardiovasc Interv. 2001;52(3):289-295. 
2. Brilakis ES, Grantham JA, Rinfret S, et al.  A percutaneous treatment algorithm for crossing coronary chronic total occlusions. JACC Cardiovasc Interv. 2012;5(4):367-379.
3. Morino Y, Abe M, Morimoto T, et al. Predicting successful guidewire crossing through chronic total occlusion of native coronary lesions within 30 minutes: the J-CTO (Multicenter CTO Registry in Japan) score as a difficulty grading and time assessment tool. JACC Cardiovasc Interv. 2011;4(2):213-221.
4. Bardají A, Rodriguez-López J, Torres-Sánchez M. Chronic total occlusion: to treat or not to treat. World J Cardiol. 2014;6(7):621-629.
5. Pershad A, Eddin M, Girotra S, et al. Validation and incremental value of the hybrid algorithm for CTO PCI. Catheter Cardiovasc Interv. 2014 Jan 9. 

From the ¹Cavanagh Heart Center, Banner Good Samaritan Medical Center, Phoenix, Arizona; ¹University of Washington Regional Heart Center, Seattle, Washington; ³Wake Forest School of Medicine, Winston-Salem, North Carolina; and ⁴Scottsdale Healthcare Shea Medical Center, Scottsdale, Arizona.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted May 9, 2014, provisional acceptance given May 27, 2014, final acceptance given June 2, 2014.

Address for correspondence: Ashish Pershad, MD, FACC, FSCAI, Cavanagh Heart Center, 1300 N. Edwards Plaza Suite 407, Phoenix AZ 85006. Email: ashish.pershad@bannerhealth.com