CTO Guide

Circulation
WHITE PAPER
Guiding Principles for Chronic Total Occlusion

Percutaneous Coronary Intervention
A Global Expert Consensus Document
ABSTRACT: Outcomes of chronic total occlusion (CTO) percutaneous Emmanouil S. Brilakis,

coronary intervention (PCI) have improved because of advancements in MD, PhD
equipment and techniques. With global collaboration and knowledge et al
sharing, we have identified 7 common principles that are widely accepted
as best practices for CTO-PCI.
1. Ischemic symptom improvement is the primary indication for CTO-PCI.
2. Dual coronary angiography and in-depth and structured review of the
angiogram (and, if available, coronary computed tomography angiog-
raphy) are key for planning and safely performing CTO-PCI.
3. Use of a microcatheter is essential for optimal guidewire manipulation
and exchanges.
4. Antegrade wiring, antegrade dissection and reentry, and the retro-
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grade approach are all complementary and necessary crossing strate-

gies. Antegrade wiring is the most common initial technique, whereas
retrograde and antegrade dissection and reentry are often required
for more complex CTOs.
5. If the initially selected crossing strategy fails, efficient change to an
alternative crossing technique increases the likelihood of eventual
PCI success, shortens procedure time, and lowers radiation and con-
trast use.
6. Specific CTO-PCI expertise and volume and the availability of special-
ized equipment will increase the likelihood of crossing success and
facilitate prevention and management of complications, such as
perforation.
7. Meticulous attention to lesion preparation and stenting technique,
often requiring intracoronary imaging, is required to ensure opti-
mum stent expansion and minimize the risk of short- and long-term
adverse events.
These principles have been widely adopted by experienced CTO-PCI
operators and centers currently achieving high success and acceptable
complication rates. Outcomes are less optimal at less experienced centers,
highlighting the need for broader adoption of the aforementioned 7
Full author list is available on page 428
guiding principles along with the development of additional simple and
safe CTO crossing and revascularization strategies through ongoing Key Words: coronary occlusion
◼ methods ◼ percutaneous coronary
research, education, and training. intervention ◼ treatment outcome
© 2019 American Heart Association, Inc.
https://www.ahajournals.org/journal/circ
420 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

Brilakis et al CTO-PCI Global Expert Consensus Document
C
hronic total occlusions (CTOs) are completely P=0.003) and quality of life (subscale change difference,
occluded coronary arteries with Thrombolysis In 6.62; 95% CI, 1.78–11.46; P=0.007), as assessed with
STATE OF THE ART

Myocardial Infarction 0 flow with an estimated the Seattle Angina Questionnaire.1 The single-center
duration of at least 3 months. In recent years, the IMPACTOR-CTO trial (Impact on Inducible Myocardial
success rates of CTO percutaneous coronary inter- Ischemia of Percutaneous Coronary Intervention versus
vention (PCI) have substantially improved, in concert Optimal Medical Therapy in Patients with Right Coro-
with the maturation and refinement of the key indi- nary Artery Chronic Total Occlusion) randomly assigned
cations, equipment, and techniques for recanalization 94 patients with isolated right coronary artery CTO to
of occluded coronary arteries. Global collaboration and CTO-PCI versus optimal medical therapy alone.2 At 12
sharing of knowledge and techniques have led to the months, in comparison with optimal medical therapy,
emergence of 7 key principles for the performance of patients undergoing CTO-PCI had a significant reduc-
CTO-PCI that can help training, clinical practice, and tion in ischemic burden and improvement in 6-minute
education in this field (Table 1). walk distance and quality of life as assessed by the
This document was conceived during CTO-PCI meet- Short Form-36 Health Survey. Such symptomatic im-
ings in 2018 (CTO Summit, Multi-Level CTO, and Euro- provement confirms results from multiple observational
CTO). An initial document draft was created by a group studies and meta-analyses.4–6 Interpretation of random-
of CTO-PCI experts from North America, Europe, and ized CTO-PCI trials should take into consideration selec-
Japan. A total of 113 CTO-PCI experts from 56 coun- tion bias, because the most symptomatic patients were
ties were invited to participate, of whom 101 from 50 less likely to be enrolled, and crossover between arms.
countries provided comments and approved the final For example, no symptomatic benefits were observed in
document. a third randomized trial, DECISION CTO (Drug-Eluting
Stent Implantation Versus Optimal Medical Treatment
in Patients With Chronic Total Occlusion).7 However
SYMPTOM IMPROVEMENT IS THE this study enrolled patients with minimal symptoms,
PRIMARY INDICATION FOR CTO-PCI and crossover rates were high in both treatment arms,
moving the outcomes toward the null. In addition, no
Two published randomized, controlled clinical trials1,2
sham-controlled trial has yet been performed, leaving
and several observational studies3 have reported symp-
the possibility that some of the observed benefit of
tom improvement after successful CTO-PCI. The Eu-
CTO-PCI is mediated by the placebo effect. One such
roCTO multicenter trial (A Randomized Multicentre Trial

trial is underway, the SHINE-CTO trial (Sham-controlled
to Evaluate the Utilization of Revascularization or Opti-
Intervention to Improve QOL in CTOs; NCT02784418).
mal Medical Therapy for the Treatment of Chronic Total
In observational studies, CTO-PCI relieved regional
Coronary Occlusions) randomly assigned 396 patients
ischemia and has been associated with improved ex-
to CTO-PCI versus optimal medical therapy alone. At 12
ercise capacity, increased anaerobic threshold,8 and
months, in comparison with patients randomly assigned
improvement in depression.9 Viable myocardium sup-
to medical therapy only, patients randomly assigned to
plied by a CTO is a persistently ischemic zone.10,11 It
CTO-PCI had greater improvement in angina frequency
remains undetermined whether CTO-PCI improves
(subscale change difference, 5.23; 95% CI, 1.75–8.71;
other cardiovascular outcomes, such as left ventricu-
lar ejection fraction, risk for arrhythmias, and mortal-
Table 1. Key Principles on the Indications and Technique of Chronic
ity. Both regional and global left ventricular function
Total Occlusion Percutaneous Coronary Intervention
improved after successful CTO-PCI in several carefully
1 The principal indication for CTO-PCI is to improve symptoms. performed observational studies12 using paired car-
2 Dual coronary angiography and thorough, structured diac magnetic resonance imaging in patients with de-
angiographic review should be performed in every case.
monstrable viability or baseline dysfunction,13 but not
3 Use of a microcatheter is essential for guidewire support. in 2 randomized, controlled trials.14,15 These random-
4 There are 4 CTO crossing strategies: antegrade wire escalation, ized studies, however, were performed in patients
antegrade dissection/reentry, retrograde wire escalation, and with normal mean left ventricular ejection fraction
retrograde dissection/reentry.
and did not examine the presence of viable dysfunc-
5 Change of equipment and technique increases the likelihood of
success and improves the efficiency of the procedure.
tional myocardium at baseline, nor did they assess ex-
ercise-induced changes in left ventricular function. In
6 Centers and physicians performing CTO-PCI should have the
necessary equipment, expertise, and experience to optimize
patients with ischemic cardiomyopathy with reduced
success and minimize and manage complications. ejection fraction, the presence of ischemia and vi-
7 Every effort should be made to optimize stent deployment in ability in the myocardium supplied by the CTO vessel
CTO PCI, including the frequent use of intravascular imaging. should be confirmed before considering CTO revascu-
CTO indicates chronic total occlusion; and PCI, percutaneous coronary larization. Patients with coronary CTOs who received
intervention. an implantable cardioverter defibrillator for primary
Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797 July 30, 2019 421

or secondary prevention had a higher risk for ven- DUAL ANGIOGRAPHY AND DETAILED,
tricular arrhythmias than patients with nonocclusive
STRUCTURED ANGIOGRAPHIC REVIEW
STATE OF THE ART
coronary artery disease.16,17 and a higher frequency

of recurrent ventricular tachycardia after ablation18; The simplest, yet most powerful technique for improving
there have been no randomized studies, however, ex- technical success and reducing complications of CTO-
amining whether CTO-PCI reduces the risk for subse- PCI is the performance of high-quality, simultaneous
quent arrhythmias. In observational studies, patients dual coronary angiography. The use of 2 catheters and
presenting with ST-segment–elevation acute myocar- pressure-monitoring systems adds little time and cost to
dial infarction and a CTO in a nonculprit coronary ar- the procedure. Dual coronary angiography allows better
tery had higher risk for developing cardiogenic shock visualization and understanding of CTO anatomy and
and higher mortality.19 is pivotal in estimating the complexity of the lesion and
In several observational studies of successful versus the likelihood of success. Moreover, it improves proce-
failed CTO-PCI, patients with successful procedures had dural safety by elucidating the guidewire location during
lower mortality than those who had unsuccessful pro- crossing attempts and facilitating the management of
cedures, but observational studies are subject to bias.4,20 periprocedural complications, such as perforation. CTO-
PCI with a single guide can be performed in selected
Observational studies have also demonstrated a lower
cases with collateral circulation exclusively coming from
incidence of major adverse cardiac events with CTO-
ipsilateral vessels, for example, in CTOs located in a left
PCI21,22 in comparison with medical therapy alone, even
dominant system.28 In the latter scenario, selective con-
among patients with well-developed collateral circula-
trast injection in the collateral donor branch through
tion.23 Although CTO-PCI may improve hard outcomes,
a microcatheter can be performed to reduce contrast
especially in patients with large ischemic burden (eg,
administration and to avoid propagation of antegrade
ischemia of >10% of the myocardium) in whom com-
dissection zones. The ping-pong technique, ie, the use
plete revascularization is achieved,24,25 this hypothesis
of 2 catheters in the left main coronary artery, will allow
will require confirmation in well-designed, prospective,
for easier guidewire and microcatheter management,
randomized, controlled clinical trials, such as the ongo-
especially when using a retrograde approach.
ing ISCHEMIA-CTO trial (Nordic and Spanish Random-
Before the procedure, a detailed review and analysis
ized Trial on the Effect of Revascularization or Optimal
of the angiogram and, if available, coronary computed
Medical Therapy of Chronic Total Coronary Occlusions
tomography angiography (CCTA) is essential for creat-
With Myocardial Ischemia; NCT03563417) and the

ing a primary and secondary procedural plan and as-
NOBLE-CTO study (Nordic-Baltic Randomized Registry sessing the risk/benefit ratio of the procedure. To allow
Study for Evaluation of PCI in Chronic Total Coronary adequate time for procedural planning and preparation
Occlusion; NCT03392415). and for proper counseling of patients, ad hoc CTO-PCI
In the 2011 American College of Cardiology/Ameri- is discouraged in most cases. CTO-PCI preplanning can
can Heart Association PCI guidelines, CTO-PCI carries a also help minimize contrast and radiation dose, reduce
class IIA/level of evidence B recommendation: “PCI of patient and operator fatigue, allow additional evalua-
a CTO in patients with appropriate clinical indications tion (such as myocardial viability) to be performed, and
and suitable anatomy is reasonable when performed enable detailed discussion with the patient about all the
by operators with appropriate expertise.”26 The 2018 aspects of the CTO-PCI procedure.
European Society of Cardiology/European Associa- CTO anatomy will dictate the most likely success-
tion of Cardiothoracic Surgery guidelines on myocar- ful and safest crossing strategies. Angiographic re-
dial revascularization CTO-PCI carries a class IIA/level of view of the CTO anatomy focuses on 4 characteristics
evidence B recommendation: “Percutaneous recanali- (Figure 1): (1) proximal cap morphology; (2) occlusion
zation of CTOs should be considered in patients with length, course, and composition (eg, calcium); (3) qual-
angina resistant to medical therapy or with large area ity of the distal vessel; and (4) characteristics of the col-
of documented ischemia in the territory of the occlud- lateral circulation.29,30 Moreover, non-CTO lesions are
ed vessel.”27 In summary, improving patient symptoms reviewed, because assessing intermediate left main or
caused by myocardial ischemia (angina, exertional dys- other lesions may change clinical decision making lead-
pnea, and sometimes fatigue) despite optimal medical ing to alternative revascularization strategies, such as
therapy remains the only benefit of CTO-PCI that has coronary artery bypass graft surgery or pre–CTO-PCI
been demonstrated in randomized, controlled trials and stenting of a donor artery.
should therefore currently be the primary indication for
offering this procedure to patients. An office-based
risk/benefit conversation with prospective patients un- Proximal Cap Morphology
dergoing CTO-PCI is strongly encouraged to provide Determining the location and morphology of the proxi-
realistic expectations before the procedure. mal cap is critical for selecting an optimal approach to

STATE OF THE ART

Figure 1. The 4 key angiographic param-
eters that need to be assessed to plan
chronic total occlusion percutaneous coro-
nary intervention.
Reproduced from Brilakis30 with permission.
Copyright © 2017, Elsevier.
CTO-PCI. Attempts to cross ambiguous proximal caps small because of hypoperfusion, leading to negative
may lead to perforation. Additional angiographic pro- remodeling, and will increase in size after recanaliza-
jections using dual injection, selective contrast injection tion.37 Distal CTO caps in native coronary artery CTOs
through a microcatheter located near the proximal cap, are more likely to be calcified and resistant to guide-
use of intravascular ultrasound,31 or preprocedural or wire penetration in patients with previous coronary
real-time CCTA coregistration32 may help clarify the lo- artery bypass grafting. Moreover, distal vessel calcifi-
cation of the proximal cap.33 If proximal cap ambiguity cation may hinder wire reentry in case of subintimal
cannot be resolved, a retrograde approach is often rec- guidewire entry.
ommended as primary strategy.

Collateral Circulation
Lesion Length, Course, and Composition Evaluation of the collateral circulation is critical for de-
Lesion length is often overestimated with antegrade- termining the feasibility of the retrograde approach.38
only injections because of underfilling and poor opaci- High-quality angiography (ideally obtained during
fication of the distal vessel, from competing antegrade breath hold and without panning), allowing complete
and retrograde coronary flow, leaving uncertainty about opacification of collateral vessels and obtained in opti-
the location and morphology of the distal cap. Dual in- mal angiographic projections, should therefore be en-
jection or preprocedural CCTA34 allows more accurate couraged as part of the routine diagnostic studies when
estimation of CTO length and the distal cap anatomy. a CTO is found. Retrograde access to the distal vessel can
Severe calcification and tortuosity of the occluded seg- be obtained via septal collaterals, epicardial collaterals,
ment can hinder CTO crossing and increase the like- or (patent or occluded) coronary bypass grafts. When
lihood of subadventitial guidewire entry. Advancing a assessing collateral channels, it is important to consider
knuckled (J-shaped) guidewire or changing to the ret- size, tortuosity, bifurcations, angle of entry to and exit
rograde approach is often preferred when the vessel from the collateral, and distance from the collateral exit
course is unclear or highly tortuous,35 because such a to the distal cap. The most important predictor of suc-
J-shaped or knuckled wire allows advancement within cessful guidewire and device crossing is lack of tortu-
the vessel architecture with a low risk of perforation.36 osity, followed by size.39 The size of the collaterals is
often assessed by using the Werner classification (CC0,
no continuous connection; CC1, threadlike connection;
Distal Vessel and CC2, side branch-like connection).10 Crossing in-
A distal vessel of large caliber (>2.0 mm) that fills well visible septal collateral channels is often possible with
does not have significant disease and is free from ma- the surfing technique, letting the wire find the path of
jor branches facilitates CTO recanalization. Conversely, least resistance.40 It is helpful to carefully study previous
small, diffusely diseased distal vessels are more chal- angiograms for multiple potential collateral pathways,
lenging to recanalize, especially after subintimal guide- because the predominant collateral may change over
wire entry. In some cases, however, distal vessels are the time before the procedure or during the course of

PCI (shifting collaterals). Previously visualized collaterals include the PROGRESS-CTO score,48 the RECHARGE
that disappear at the time of the procedure may still (Registry of Crossboss and Hybrid Procedures in France,
STATE OF THE ART
be crossable. Whenever required, and after ensuring the Netherlands, Belgium and United Kingdom) registry
adequate backflow to prevent barotrauma, selective score,49 the CL-score (Clinical and Lesion related score),50
contrast tip injections through the microcatheter can the ORA (ostial location, collateral filling of Rentrop <2,
be safely performed to outline collateral anatomy. Pat- age >75) score,51 the Ellis et al52 score, the weighted
ent bypass grafts represent an ideal retrograde conduit angiographic scoring model (W-CTO score),53 and the
because of the absence of side branches, predictable CASTLE (coronary artery bypass grafting history, age
course, and large caliber. Even occluded grafts can be [≥70 years], stump anatomy [blunt or invisible], tortuos-
used as retrograde pathways. However, in case of col- ity degree [severe or unseen], length of occlusion [≥20
lateral circulation originating from the left anterior de- mm], and extent of calcification [severe]) score.54 There
scending artery, that is supplied by a mammary artery, are also CCTA-based scores, such as the CT-RECTOR
access via the internal mammary artery graft increas- multicenter registry (Computed Tomography Registry
es the risk of global ischemia and should be avoided of Chronic Total Occlusion Revascularization) score55
whenever possible.41 and the Korean Multicenter CTO CT Registry Score.56
Septal collaterals are typically safer and easier to Various scores have similar predictive capacity for tech-
navigate using very soft tip and polymer-jacketed nical success and are more accurate in antegrade-only
guidewires in comparison with epicardial collater- cases.57 The risk of complications can be assessed by
als.42,43 In contrast to epicardial collaterals, septal col- using the Progress-CTO complications score that uses
laterals can be safely dilated with small balloons to 3 variables (age ≥65 years, lesion length >23 mm, and
facilitate microcatheter or device crossing if required. use of the retrograde approach) to stratify patients for
The donor vessel proximal to the collateral origin, and the risk of periprocedural complications.58
collateral dominance (ie, presence of a single large vis- In general, each score is only applicable to the pop-
ible collateral), should also be assessed during retro- ulation from which it was derived and validated. Cal-
grade procedures to determine the risk for ischemia culating ≥1 scores can promote detailed review of the
during retrograde crossing attempts. Careful review of angiogram and facilitate decision making. For example,
collaterals before the procedure can reduce contrast medical therapy may be preferred over CTO-PCI in
and radiation dose, and the duration of the procedure. mildly symptomatic patients with highly complex occlu-
In cases where the collateral anatomy is unclear or am- sions. Complex CTOs (such as those with J-CTO score
biguous, it can be helpful to perform selective injection ≥2) are more likely to require dissection reentry and ret-
of contrast into the collateral through the center lu- rograde crossing techniques and should be performed
men of a microcatheter placed into the collateral by us- by experienced operators.
ing a 2- to 3-mL syringe. Furthermore, in cases where
unfavorable noninterventional epicardial collaterals
provide the dominant blood flow to the CTO, it can be USE OF A MICROCATHETER FOR
useful to balloon occlude the epicardial collateral for
GUIDEWIRE MANIPULATION
2 to 4 minutes to see if more favorable interventional
collaterals can be recruited and identified for attempts A microcatheter should be routinely used for supporting
at retrograde crossing. the coronary guidewire and allowing rapid guidewire
switching during both antegrade and retrograde wire
manipulation. Microcatheters improve the precision of
CTO Scores both rotational and longitudinal guidewire movements
Angiographic and clinical characteristics, such as previ- both in fluid (blood-filled vessels) and in tissue (the oc-
ous CTO-PCI failure44 and previous coronary artery by- clusion itself) and allow the penetration force of the
pass grafting,45 have been combined to create scores wire to be dynamically altered by changing the distance
for estimating the difficulty and hazard of a specific between the tip of the guidewire and the microcath-
CTO-PCI in various patient populations. The first and eter, with guidewires becoming stiffer when the micro-
most commonly used CTO-PCI score is the J-CTO score catheter is positioned close to the guidewire tip. Micro-
(Multicenter CTO Registry of Japan), developed to esti- catheters also allow rapid guidewire tip reshaping or
mate the likelihood of successful antegrade guidewire exchange, while preserving previous guidewire crossing
crossing within 30 minutes based on 5 criteria (at least or advancement achieved. Microcatheters inherently
1 bend of >45° in the CTO entry or CTO body, occlusion dilate retrograde collateral channels and protect them
length >20 mm, calcification, blunt proximal stump, from wire-induced trauma. Microcatheters can also be
and previously failed attempt).46 The J-CTO score has used to deliver contrast either for visualization or to ac-
been validated in other CTO-PCI cohorts44 and is also complish the Carlino technique (intralesional injection
associated with 1-year clinical outcomes.47 Other scores of 1–2 mL of contrast to elucidate microcatheter posi-

tion and facilitate crossing), especially in wire-resistant enters the subintimal space, it can be redirected, but
lesions.59 A microcatheter is preferred over an over-the- if this maneuver fails, the wire can be left in place to
STATE OF THE ART

wire balloon because it has a marker at the distal tip, aid directing a second guidewire into the distal true lu-
providing adequate fluoroscopic feedback of its actual men (parallel-wire technique), which can be assisted by
position and also providing greater freedom of advance- a dual-lumen microcatheter or facilitated by the use of
ment with a lower profile and better wire-to-lumen in- intravascular ultrasound.31 Alternatively, antegrade dis-
ternal diameter ratio. Also, unlike over-the-wire plastic section/reentry techniques can be used to reenter into
balloon catheter shafts that are prone to kinking, nearly the distal true lumen, as described below. Subintimal
all contemporary coronary microcatheters incorporate a guidewire advancement distal to the distal cap should
kink-resistant metallic braid. be avoided because it can lead to hematoma forma-
Similar to guidewires, microcatheter selection de- tion, causing luminal compression and reducing the
pends on the CTO angiographic characteristics, local likelihood of success. Antegrade vessel reentry can be
availability, and expertise. In addition to using a micro- guided by intravascular ultrasound, although this ap-
catheter, obtaining coaxial guide position and strong proach requires expertise and may be hindered by lim-
guide support can significantly facilitate CTO crossing. ited wire maneuverability in the presence of the subin-
timal intravascular ultrasound catheter.
CTO CROSSING STRATEGIES

Antegrade Dissection and Reentry
There are 4 CTO crossing strategies, classified accord-
ing to wiring direction (antegrade and retrograde) and Antegrade dissection and reentry involves entering the
whether or not the subintimal space is used (wiring ver- subintimal space, followed by subintimal crossing of the
sus dissection and reentry; Figure 2).29,30 CTO with subsequent reentry into the distal true lumen.
Antegrade dissection and reentry may be intentional or
unintentional during antegrade wiring attempts. The
Antegrade Wiring first developed dissection reentry technique was named
Antegrade wiring (also called antegrade wire esca- STAR (Subintimal Tracking And Re-Entry) and used inad-
lation) is the most widely used CTO crossing tech- vertent, uncontrollable reentry into the distal lumen.63
nique.31,60–62 Various guidewires are advanced in the This frequently necessitated stenting long coronary seg-
ments with occlusion of numerous side branches, lead-
antegrade direction (original direction of blood flow).

Guidewire choice depends on CTO characteristics. If ing to extensive vascular injury and high rates of in-stent
there is a tapered proximal cap or a functional occlu- restenosis and reocclusion.63–65 As such, the STAR tech-
sion with a visible channel, a polymer-jacketed, low nique has evolved to a bailout strategy without stent
penetration force, tapered guidewire is used initially, implantation after ballooning, in preparation for a re-
with subsequent escalation to intermediate and high peat CTO-PCI attempt (subintimal plaque modification,
penetration force guidewires, as required. If there is a also termed an “investment procedure”).66–68 The devel-
blunt proximal cap, antegrade wiring is usually started opment of limited dissection/reentry techniques (using
with an intermediate penetration force polymer-jacket- dedicated reentry systems69,70 or wire-based strategies71)
ed guidewire, or a composite core guidewire. Stiff, high was an important advancement, because they minimize
penetration force guidewires may be required in highly vascular injury, limit the length of dissection and subse-
resistant proximal caps or when areas of resistance are quent stent length, and increase the likelihood of side
encountered within the body of the occlusion. After branch preservation.36,69,72 Such approaches have been
proximal cap crossing of 1 to 2 mm, however, deesca- associated with favorable clinical outcomes.72–76
lation to less penetrating guidewires should follow to
navigate through the CTO segment.
Contralateral injection and orthogonal angiographic Retrograde Approach
projections are critical for determining guidewire posi- The retrograde technique differs from the antegrade
tion during crossing attempts. If the guidewire enters approach in that the occlusion is approached from the
into the distal true lumen, the microcatheter is then distal vessel with guidewire advancement against the
advanced into the distal true lumen, and the dedicat- original direction of blood flow.77 A guidewire is ad-
ed CTO guidewire is then exchanged for a workhorse vanced into the artery distal to the occlusion through a
guidewire through the microcatheter to minimize the collateral channel or through a bypass graft, followed
risk for distal vessel injury and perforation during bal- by placement of a microcatheter at the distal CTO cap.
loon angioplasty and stenting (wire deescalation). If Retrograde CTO crossing is then attempted either with
the guidewire exits the vessel structure, it should be retrograde wiring (usually for short occlusions, especial-
withdrawn and redirected without advancing micro- ly when the distal cap is tapered78) or using retrograde
catheters, balloons, or stents over it. If the guidewire dissection/reentry techniques.

STATE OF THE ART
Figure 2. Illustration of the chronic total occlusion crossing techniques.

Reproduced from Brilakis30 with permission. Copyright © 2017, Elsevier.
The most commonly used retrograde crossing tech- Asia Pacific,35 and Euro-CTO81 algorithms. Antegrade
nique is reverse controlled antegrade and retrograde crossing is generally preferred over retrograde crossing
tracking, in which a balloon is inflated over the ante- as the initial crossing strategy, given the higher risk of
grade guidewire, followed by retrograde guidewire complications with the retrograde approach60–62 and the
advancement into the space created by the antegrade need for antegrade lesion preparation even when the
balloon (Figure 2). In challenging reverse controlled retrograde approach is eventually required. Some retro-
antegrade and retrograde tracking cases, intravascular grade CTO-PCI complications, however, are caused by
ultrasound can clarify the mechanism of failure and in- antegrade crossing attempts. The retrograde approach
crease the likelihood of success.79 Guide catheter ex- remains critical for achieving high success rates, espe-
tensions can also facilitate reverse controlled antegrade cially in more complex CTOs,60,62 and has been associ-
and retrograde tracking.80 ated with favorable long-term outcomes.82
CTOs with proximal cap ambiguity and flush aorto-
ostial CTOs are often approached with a primary ret-
Crossing Strategy Selection rograde strategy. Alternatively, proximal cap ambiguity
Selecting the initial and subsequent crossing strategies can be approached in the antegrade direction, espe-
depends on the CTO lesion characteristics and local cially when no collateral or graft is available by using
equipment availability and expertise. (1) intravascular ultrasound or preprocedural CCTA for
Several algorithms have been developed to facili- determining the location of the proximal cap and ves-
tate crossing strategy selection, such as the hybrid,29 sel course,32,35,83 or (2) techniques to facilitate entry into

the subintimal space proximal to the occlusion, such as ministration (>3.7× the estimated creatinine clearance),
the balloon-assisted subintimal entry (ie, inflation of a exhaustion of crossing options, or patient or physician
STATE OF THE ART

balloon proximal to the occlusion to cause a dissection, fatigue. As with all interventions, careful assessment
followed by subintimal guidewire entry and subintimal of individual risk versus benefit should guide decision
crossing of the occlusion) technique.84 making and choice of strategy during different stages
of the procedure. On many occasions, it may be best to
fail rather than to pursue highly aggressive strategies
CHANGE OF CROSSING STRATEGY that may lead to serious complications.60
Flexibility is important for the success, safety, and ef-
ficiency of CTO-PCI. If the initial or subsequent crossing EQUIPMENT AND PHYSICIAN TEAM
strategy fails to achieve progress, small changes (such
as modifying the guidewire tip angulation or changing EXPERTISE
guidewire) or more significant changes (such as con- CTO-PCI should be performed within dedicated pro-
verting from an antegrade to a retrograde approach) grams that promote continual training and rigorous
should be made, based on preprocedural planning.29,35 monitoring of outcomes.85 Higher CTO-PCI volume
It is important to avoid getting stuck in a failure mode, has consistently been associated with higher success
in which excessive time, radiation, and contrast are ex- rates.52,86,87
pended with little or no progress being made while re- The performance of CTO-PCI by a skilled physi-
peatedly attempting the same technique, because this cian and team is especially important to minimize
will preclude the use of alternative strategies and in- and manage procedural complications. CTO-PCI car-
crease the risk of complications. ries increased risk of complications in comparison
Similar to selection of the initial crossing strategy, with non–CTO-PCI,86 especially perforation.3 Across
the timing and choice of subsequent crossing strate- multiple contemporary registries, tamponade oc-
gies depends on lesion characteristics, challenges en- curred in 0.4% to 1.3% of cases (Table 2).3,31,60–62,88,89
countered with the original technique, and equipment Additional CTO-PCI adverse events include access
availability and expertise, and can be guided by existing site complications, donor vessel injury, arrhythmias,
crossing algorithms.29,35 Only ≈50% to 60% of CTOs stroke, contrast-induced nephropathy, radiation der-
are successfully crossed with the initial strategy,28,60,61 matitis, emergency coronary bypass graft surgery, and
highlighting the need for further refinements in the death.90 The average complication risk is ≈3%, but
procedure-planning algorithms. Changing strategies varies widely between studies (Table 2) and increases
can help maximize the likelihood of eventual success with greater lesion complexity.3,60–62,88,89
and limit contrast volume and radiation dose. Dual injection minimizes the risk for perforation by
Reasons to stop a CTO-PCI attempt include occur- helping determine guidewire position. Placement of a
rence of a complication, high radiation dose (usually safety guidewire in the CTO donor vessel can facilitate
>5 Gy air kerma dose in the absence of lesion cross- treatment if donor vessel injury occurs. Maintaining an
ing or substantial progress), large contrast volume ad- activated clotting time of ≥300 to 350 seconds reduces
Table 2. Contemporary Series of Chronic Total Occlusion Percutaneous Coronary Intervention
Study Technical Procedural Overall Acute

Authors Acronym Period Centers Cases Success Success MACE Death MI Stroke TVR Tamponade
Konstantinidis EURO-CTO 2008–2015 53 17 626 85% – 0.6% 0.2% – – – 0.4%
et al89 registry
Habara et al88 Japanese 2012–2013 56 3229 – 88% 0.5% 0.2% 0.1% 0.1% – 0.3%
Retrograde
Summit Registry
Tajti et al60 PROGRESS-CTO 2012–2017 20 3055 87% 85% 3.0% 0.3% 0.7% 0.1% 0.2% 0.5%
Suzuki et al31 Japanese CTO- 2014–2015 41 2846 90% 89% <2% 0.2% 1.2% 0.2% 0.2% 0.4%
PCI Expert
Registry
Maeremans RECHARGE 2014–2015 17 1253 89% 86% 2.6% 0.2% 0.2% 2.2% 0.1% 1.3%
et al61
Wilson et al62 UK Hybrid 2012–2014 7 1156 90% — 1.6% 0.0% 0.8% 0.4% 0.0% 0.7%
Sapontis et al3 OPEN-CTO 2013–2017 12 1000 86% 85% 7.0% 0.9% 2.6% 0.0% 0.1% –
The studies are listed according to the number of patients included. EURO-CTO indicates European Registry of Chronic Total Occlusion; MACE indicates major
adverse cardiac events; MI, myocardial infarction; OPEN CTO, Outcomes, Patient Health Status, and Efficiency in Chronic Total Occlusion Hybrid Procedures;
PROGRESS-CTO, Prospective Global Registry for the Study of Chronic Total Occlusion Intervention; RECHARGE, Registry of Crossboss and Hybrid procedures in
France, The Netherlands, Belgium, and United Kingdom; UK hybrid, United Kingdom hybrid registry; and TVR, target vessel revascularization.

the risk of donor vessel thrombosis; the activated clot- global expert consensus document. These principles can
ting time should be checked at least every 30 minutes guide training of new CTO-PCI operators and program
STATE OF THE ART
during the procedure. In case of perforation, covered development and facilitate further improvement in the
stents and coils should be available to treat large ves- success, safety, and clinical outcomes of CTO-PCI.
sel and distal vessel perforations, respectively. Prepro-
cedural operator training in the proper use of these
devices will ensure efficient use in the emergency set- ARTICLE INFORMATION
ting. In case of epicardial collateral perforation,43,91 em- Authors
bolization from both directions (using coils, thrombin, Emmanouil S. Brilakis, MD, PhD; Kambis Mashayekhi, MD; Etsuo Tsuchikane,
MD, PhD; Nidal Abi Rafeh, MD; Khaldoon Alaswad, MD; Mario Araya, MD;
fat, etc) is often needed to achieve sealing.92 Special
Alexandre Avran, MD; Lorenzo Azzalini, MD, PhD, MSc; Avtandil M. Babunashvili,
attention should be given to patients with previous MD; Baktash Bayani, MD; Ravinay Bhindi, MD; Nicolas Boudou, MD; Marouane
coronary bypass graft surgery, because perforation can Boukhris, MD; Nenad Ž. Božinović, MD; Leszek Bryniarski, MD, PhD; Alexander
Bufe, MD; Christopher E. Buller, MD; M. Nicholas Burke, MD; Heinz Joachim
result in life-threatening, difficult to access, loculated
Büttner, MD; Pedro Cardoso, MD; Mauro Carlino, MD; Evald H. Christiansen,
hematomas93 or bleeding in the mediastinum or pleu- MD; Antonio Colombo, MD; Kevin Croce, MD, PhD; Felix Damas de los Santos,
ral cavities. MD; Tony De Martini, MD; Joseph Dens, MD, PhD; Carlo Di Mario, MD; Kefei
Dou, MD; Mohaned Egred, MD; Ahmed M. ElGuindy, MD; Javier Escaned, MD,
Meticulous attention should also be paid to minimiz-
PhD; Sergey Furkalo, MD; Andrea Gagnor, MD; Alfredo R. Galassi, MD; Roberto
ing radiation dose and the risk for radiation skin injury. Garbo, MD; Junbo Ge, MD; Pravin Kumar Goel, MD; Omer Goktekin, MD; Luca
This can be achieved by using low-frame rate fluorosco- Grancini, MD; J. Aaron Grantham, MD; Colm Hanratty, MD; Stefan Harb, MD;
Scott A. Harding, MD; Jose P.S. Henriques, MD; Jonathan M. Hill, MD; Farouc
py and the fluoroscopy-store function for documenting
A. Jaffer, MD, PhD; Yangsoo Jang, MD; Risto Jussila, MD; Artis Kalnins, MD;
balloon and stent inflation instead of cine-angiography, Arun Kalyanasundaram, MD; David E. Kandzari, MD; Hsien-Li Kao, MD; Dimitri
using collimation, minimizing the distance of the image Karmpaliotis, MD, PhD; Hussien Heshmat Kassem, MD, PhD; Paul Knaapen,
MD; Ran Kornowski, MD; Oleg Krestyaninov, MD; A. V. Ganesh Kumar, MD;
receptor from the patient, and intermittently changing
Peep Laanmets, MD; Pablo Lamelas, MD; Seung-Whan Lee, MD; Thierry Lefevre,
the position of the image receptor during the proce- MD; Yue Li, MD; Soo-Teik Lim, MD; Sidney Lo, MBBS; William Lombardi, MD;
dure.94,95 Patients who receive high doses of radiation Margaret McEntegart, MD, PhD; Muhammad Munawar, MD; José Andrés Na-
varro Lecaro, MD; Hung M. Ngo, MD, PhD; William Nicholson, MD; Göran K.
(eg, >5 Gray air kerma dose) require formal follow-up
Olivecrona, MD, PhD; Lucio Padilla, MD; Marin Postu, MD; Alexandre Quad-
to evaluate for subacute skin injury. Similarly, contrast ros, MD; Franklin Hanna Quesada, MD; Vithala Surya Prakasa Rao, MD; Nico-
administration should be minimized through meticu- laus Reifart, MD; Meruzhan Saghatelyan, MD; Ricardo Santiago, MD; George
lous preprocedural planning and use of contrast-spar- Sianos, MD, PhD; Elliot Smith, MD; James C. Spratt, MD; Gregg W. Stone,
MD; Julian W. Strange, MD; Khalid Tammam, MD, PhD; Imre Ungi, MD, PhD;
ing devices to reduce the risk for contrast nephropathy. Minh Vo, MD; Vu Hoang Vu, MD; Simon Walsh, MD; Gerald S. Werner, MD;
Jason R. Wollmuth, MD; Eugene B. Wu, MD; R. Michael Wyman, MD; Bo Xu,
MD; Masahisa Yamane, MD; Luiz F. Ybarra, MD; Robert W. Yeh, MD; Qi Zhang,
OPTIMAL STENT DEPLOYMENT MD; Stephane Rinfret, MD, SM
CTO-PCI often involves placement of multiple stents in Correspondence

vessels that are calcified, diffusely diseased, and nega- Emmanouil S. Brilakis, MD, PhD, Minneapolis Heart Institute, 920 E 28th St
tively remodeled. Given the often arduous and lengthy #300, Minneapolis, MN 55407. Email esbrilakis@gmail.com
attempts required for CTO crossing, less attention may
be given to stent optimization (maximal stent expan- Affiliations
sion and optimal inflow and outflow), potentially result- Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott
ing in higher rates of restenosis and stent thrombosis. Northwestern Hospital, MN (E.S.B., M.N.B.). Department of Cardiology and An-
giology II University Heart Center Freiburg Bad Krozingen, Germany (K.M.,
Full lesion expansion should be achieved before stent H.J.B.). Toyohashi Heart Center, Aichi, Japan (E.T.). St. George Hospital Univer-
implantation by predilation with properly sized balloon sity Medical Center, Beirut, Lebanon (N.A.R.). Henry Ford Hospital, Detroit, MI
or atherectomy. Intravascular imaging can facilitate the (K.A.). Clínica Alemana and Instituto Nacional del Tórax, Santiago, Chile (M.A.).
Arnault Tzank Institut St. Laurent Du Var Nice, France (A.A.). Interventional
assessment of vessel size and calcification before stent- Cardiology Division, Cardio-Thoracic-Vascular Department, San Raffaele Scien-
ing and the adequacy of stent expansion, apposition tific Institute, Milan, Italy (L.A., M.C.). Department of Cardiovascular Surgery,
and lesion coverage, to reduce the risk for subsequent Center for Endosurgery and Lithotripsy, Moscow, Russian Federation (A.M.B.).
Cardiology Department, Mehr Hospital, Mashhad, Iran (B.B.). Department of
adverse events.96–99 Moderate diffuse disease distal to Cardiology, Royal North Shore Hospital and Kolling Institute, University of Syd-
the CTO often does not require treatment, because the ney, Australia (R.B.). Rangueil University Hospital, Toulouse, France (N.B.). Car-
distal vessel often enlarges over time after restoring diology department, Abderrahment Mami Hospital, Faculty of Medicine of Tu-
nis, University of Tunis El Manar, Tunisia (M.B.). Department of Interventional
vessel patency.100 Cardiology Clinic for Cardiovascular Diseases University Clinical Center Nis,
Serbia (N.Z.B.). II Department of Cardiology and Cardiovascular Interventions
Institute of Cardiology, Jagiellonian University Medical College, Cracow, Poland
CONCLUSIONS (L.B.). Department of Cardiology, Heartcentre Niederrhein, Helios Clinic Krefeld,

Krefeld, Germany, Institute for Heart and Circulation Research, University of
Extensive interactions and collaboration across the Cologne, Germany, and University of Witten/Herdecke, Witten, Germany
(A.B.). St. Michael’s Hospital, Toronto, ON, Canada (C.E.B.). Cardiology Depart-
world have led to the advancements in CTO-PCI that ment, Santa Maria University Hospital (CHULN), Lisbon Academic Medical Cen-
are summarized in the 7 key principles outlined in this tre (CAML) and Centro Cardiovascular da Universidade de Lisboa (CCUL), Por-

tugal (P.C.). Department of Cardiology, Aarhus University Hospital, Denmark Cardiology, Bristol Royal Infirmary, United Kingdom (J.W.S.). Cardiac Center of
(E.H.C.). San Raffaele Hospital and Columbus Hospital, Milan, Italy (A.C.). Car- Excellence, International Medical Center, Jeddah, Saudi Arabia (K.T.). 2nd De-
STATE OF THE ART

diovascular Division, Brigham and Women’s Hospital, Boston, MA (K.C.). Inter- partment of Internal Medicine and Cardiology Center, University of Szeged,
ventional Cardiology Department, Instituto Nacional de Cardiología Ignacio Hungary (I.U.). Mazankowski Alberta Heart Institute, Edmonton, AB, Canada
Chávez Mexico City, Mexico (F.D.d.l.S.). SIU School of Medicine, Memorial (M.V.). Interventional Cardiology Department, Heart Center, University Medical
Medical Center, Springfield, IL (T.D.M.). Department of Cardiology, Hospital Center at Ho Chi Minh City, and University of Medicine and Pharmacy, Vietnam
Oost-Limburg, Genk, Belgium (J.D.). Structural Interventional Cardiology, (H.V.). Medizinische Klinik I Klinikum Darmstadt GmbH, Germany (G.W.). Provi-
Careggi University Hospital, Florence, Italy (C.D.M.). Center for Coronary Heart dence Heart and Vascular Institute, Portland, OR (J.R.W.). Prince of Wales Hos-
Disease, State Key Laboratory of Cardiovascular Disease, Fu Wai Hospital, and pital, Hong Kong (E.W.). Torrance Memorial Medical Center, CA (R.M.W.). Fu
National Center for Cardiovascular Diseases, Chinese Academy of Medical Sci- Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of
ences and Peking Union Medical College,Beijing (K.D.). Freeman Hospital and Medical Sciences, Beijing (B.X.). Saitima St. Luke’s International Hospital, Tokyo,
Newcastle University, Newcastle upon Tyne, United Kingdom (M.E.). Depart- Japan (M.Y.). London Health Sciences Centre, Schulich School of Medicine &
ment of Cardiology, Aswan Heart Center, Egypt (A.M.E.). National Heart and Dentistry, Western University, London, Ontario, Canada (L.F.Y.). Beth Israel Dea-
Lung Institute, Imperial College London, United Kingdom (A.M.E.). Hospital coness Medical Center, Boston, MA (R.W.Y.). Shanghai East Hospital, Tongji
Clinico San Carlos IDISSC and Universidad Complutense de Madrid, Spain (J.E.). University, China (Q.Z.). McGill University Health Centre, McGill University,
Department of Endovascular Surgery and Angiography, National Institute of Montreal, QC, Canada (S.R.).
Surgery and Transplantology of AMS of Ukraine, Kiev (S.F.). Department of In-
vasive Cardiology, Maria Vittoria Hospital, Turin, Italy (A.G.). Chair of Cardiolo-
gy, Department of PROMISE, University of Palermo, Italy (A.R.G.). Director of
Acknowledgment
Interventional Cardiology, San Giovanni Bosco Hospital, Turin, Italy (R.G.). We recognize the assistance of Dr Iosif Xenogiannis in the creation of this docu-
Zhongshan Hospital, Fudan University, Shanghai, China (J.G.). Sanjay Gandhi ment.
Post Graduate Institute of Medical Sciences Lucknow, India (P.K.G.). Memorial
Hospital, Istanbul, Turkey (O.G.). Centro Cardiologico Monzino, IRCCS, Milan,
Italy (L.G.). Saint Luke’s Mid America Heart Institute, Kansas City, MO (J.A.G.).
Disclosures
Belfast Health and Social Care Trust, United Kingdom (C.H., S.W.). LKH Graz II, Dr Brilakis: Consulting/speaker honoraria from Abbott Vascular, American Heart
Standort West, Kardiologie, Teaching Hospital of the University of Graz, Austria Association (associate editor Circulation), Boston Scientific, Cardiovascular Inno-
(S.H.). Wellington Hospital, Capital and Coast District Health Board, New Zea- vations Foundation (Board of Directors), CSI, Elsevier, GE Healthcare, InfraRedx,
land (S.A.H.). Academic Medical Centre of the University of Amsterdam, The and Medtronic; research support from Regeneron and Siemens. Shareholder:
Netherlands (J.P.S.H.). King’s College Hospital, London, United Kingdom MHI Ventures. Board of Trustees: Society of Cardiovascular Angiography and
(J.M.H.). Cardiology Division, Massachusetts General Hospital, Boston (F.A.J.). Interventions. Dr Mashayekhi: Consulting/speaker/proctoring honoraria from
Division of Cardiology, Severance Cardiovascular Hospital, Yonsei University Abbott Vascular, Ashai Intecc, AstraZeneca, Biotronik, Boston Scientific, Cardinal
Health System, Seoul, South Korea (Y.J.). Helsinki Heart Hospital, Finland (R.J.). Health, Daiichi Sankyo, Medtronic, Teleflex, Terumo. Dr Tsuchikane: Consultant
Department of Cardiology, Eastern Clinical University Hospital, Riga, Latvia (A. of Boston Scientific, Asahi Intecc, Nipro, and Kaneka. Dr Abi Rafeh: CTO Proctor
Kalnins). Promed Hospital, Chennai, India (A. Kalyanasundaram). Piedmont and consultant for Boston Scientific and Abbott Vascular. Dr Alaswad: consul-
Heart Institute, Atlanta, GA (D.E.K.). Department of Internal Medicine, National tant and speaker for Boston Scientific, Abbott Cardiovascular, CSI, and LivaNova.
Taiwan University Hospital, Taipei (H.-L.K.). Columbia University, New York Dr Avran: Proctor for Boston Scientific, Biotronik, Abbott, Terumo, Biosensor,
(D.K.). Cardiology Department, Kasr Al-Ainy Faculty of Medicine, Cairo Univer- Medtronic. Dr Azzalini: Honoraria from Abbott Vascular, Guerbet, Terumo, and
sity, Egypt (H.H.K.). Fujairah Hospital, United Arab Emirates (H.H.K.). Depart- Sahajanand Medical Technologies; research support from ACIST Medical Sys-
ment of Cardiology, VU University Medical Center, Amsterdam, The Nether- tems, Guerbet, Terumo. Dr Boudou: Proctorship fees from Boston Scientific,
lands (P.K.). Department of Cardiology, Rabin Medical Center, Petach Tikva, Terumo, Abbott Vascular, and Biotronik. Dr Buller: Intellectual property: Tele-
“Sackler” School of Medicine, Tel Aviv University, Petach Tikva, Israel (R.K.). flex; consultant: Abbott Vascular, Soundbite Medical, and Philips-Volcano. Dr
Meshalkin Novosibrisk Research Institute, Russia (O.K.). Department of Cardiol- Burke: Consulting and speaker honoraria from Abbott Vascular and Boston
ogy, Dr LH Hiranandani Hospital, Mumbai, India (A.V.G.K.). North Estonia Med- Scientific. Dr Croce: Proctor/speaking honoraria: Abbott, Boston Scientific, CSI,
ical Center Foundation, Tallinn, Estonia (P. Laanmets). Department of Interven- Philips; research grant: Teleflex, Takeda; advisory board: Abiomed, Cordis. Dr
tional Cardiology and Endovascular Therapeutics, Instituto Cardiovascular de de los Santos: Speaker and proctor of Boston Scientific, Terumo, and Abbott.
Buenos Aires, Argentina (P. Lamelas). Department of Health Research Methods, Dr De Martini: Proctor and advisory board for Abbott and Boston Scientific. Dr
Evidence and Impact, McMaster University, Hamilton, ON, Canada (P. Lamelas). Dens: Consulting/speaker honoraria from Abbott Vascular, Boston Scientific,
Department of Cardiology, Asan Medical Center, University of Ulsan College of IMDS, Orbus Neich, Terumo, and Topmedical (distributor for Asahi). Dr Di M ario:
Medicine, Seoul, South Korea (S.-W.L.). Institut Cardiovasculaire Paris Sud Hopi- research grant to institution from Amgen, Behring, Chiesi, Daiichi Sankyo, Ed-
tal prive Jacques Cartier, Massy, France (T.L.). Department of Cardiology, the wards, Medtronic, Shockwave. Dr Egred: Honoraria, speaker and proctorship
First Affiliated Hospital of Harbin Medical University, China (Y.L.). Department fees from Abbott Vascular, Boston Scientific, Vascular Perspectives, Philips/Vol-
of Cardiology, National Heart Centre Singapore (S.-T.L.). Department of Cardiol- cano, Biosensors, and EPS. Dr ElGuindy: Proctorship fees from Boston Scientific.
ogy, Liverpool Hospital and The University of New South Wales, Sydney, Austra- Dr Gagnor: Consultant Boston Scientific, Terumo. Dr Garbo: Consultant Boston
lia (S.L.). University of Washington, Seattle (W.L.). Golden Jubilee National Hos- Scientific, Terumo, Philips Volcano, IMDS, and CID-Alvimedica. Dr Grantham:
pital, Glasgow, United Kingdom (M. McEntegart). Binawaluya Cardiac Center, Speaking fees, travel reimbursement, and honoraria from Boston Scientific, Ab-
Jakarta, Indonesia (M. Munawar). Médico Cardiólogo Universitario - Hemodin- bott Vascular, and Asahi Intecc. Institutional research grants Boston Scientific.
amista en Hospital de Especialidades Eugenio Espejo y Hospital de los Valles, Part-time employment and equity in Corindus Vascular Robotics. Dr Hanratty:
Ecuador (J.A.N.L.). Choray Hospital, Vietnam (H.M.N.). WellSpan Health Sys- Proctoring for Abbott, Boston Scientific, Medtronic, and Teleflex. Dr Harb:
tem, York, PA (W.N.). Skane University Hospital, University of Lund, Sweden Consultant with Medtronic, speaker´s honoraria from Medtronic and Cardinal
(G.K.O.). Department of Interventional Cardiology and Endovascular Therapeu- Health. Dr Harding: Proctor/speaker for Boston Scientific, Abbott Vascular, and
tics, ICBA, Instituto Cardiovascular, Buenos Aires, Argentina (L.P.). Cardiology Bio-Excel; consultant/speaker for Medtronic and Asahi. Dr Hill: Speaker, consul-
Department, University of Medicine and Pharmacy “Carol Davila,” Institute of tant, and proctor for Boston Scientific and Abbott Vascular. Dr Jaffer: Sponsored
Cardiovascular Diseases “Prof. Dr. C.C. Iliescu,” Bucharest, Romania (M.P.). In- research from Canon, and Siemens; consultant for Boston Scientific, Abbott Vas-
stituto de Cardiologia / Fundação Universitária de Cardiologia - IC/FUC, Porto cular, Siemens, and Philips. Massachusetts General Hospital has a patent licens-
Alegre, RS – Brazil (A.Q.). Interventional Cardiology Department, Clinica Com- ing arrangement with Canon, and Dr Jaffer has the right to receive royalties. Dr
familiar Pereira City, Colombia (F.H.Q.). Hyderguda Apollo, Hyderabad, India Jussila: Consulting agreement with EPS Vascular, Boston Scientific, and Terumo.
(V.S.P.R.). Department of Cardiology, Main Taunus Heart Institute, Bad Soden, Dr Kalyanasundaram: Speaker, consultant, and proctor for Boston Scientific,
Germany (N.R.). Nork-Marash Medical Center, Yerevan, Armenia (M.S.). Hospi- Asahi, and Abbott Vascular. Dr Kandzari: Research/grant support: Medtronic,
tal Pavia Santurce, PCI Cardiology Group, San Juan, Puerto Rico (R.S.T.). AHEPA Boston Scientific, Biotronik; consulting honoraria: Medtronic, Boston Scien-
University Hospital, Thessaloniki, Greece (G.S.). Department of Cardiology, tific, Biotronik, and CSI. Dr Kao: Speaker/proctor honoraria: Abbott Vascular,
Barts Heart Centre, St Bartholomew’s Hospital, London, United Kingdom (E.S.). Asahi Intecc, Biotronik, Boston Scientific, Medtronic, Orbus Neich, and Terumo.
St George’s University Hospital NHS Trust, London, United Kingdom (J.S.). Cen- Dr Karmpaliotis: Honoraria Boston Scientific, Abiomed and Abbott Vascular.
ter for Interventional Vascular Therapy, Division of Cardiology, New York-Pres- Dr Kornowski: Co-founder of NitiLoop. Dr Krestyaninov: Speaker and proctor
byterian Hospital/Columbia University Medical Center (G.W.S.). Department of honoraria from Abbott Vascular. Dr Laanmets: Consultant for Terumo. Dr Lee:

Speaker and proctorship honoraria from Abbott Vascular, Boston Scientific, and 8. Mashayekhi K, Neuser H, Kraus A, Zimmer M, Dalibor J, Akin I, Werner G,
Medtronic. Dr Lefevre: Proctoring for Terumo. Dr Lim: Travel support from Asahi Aurel T, Neumann FJ, Behnes M. Successful percutaneous coronary in-
STATE OF THE ART
Intecc, Terumo, Kaneka, Boston Scientific, and Abbott Vascular. Dr Lo: Travel tervention improves cardiopulmonary exercise capacity in patients with
support from Bioexcel and Abbott; speaker honoraria from Abbott, Boston Sci- chronic total occlusions. J Am Coll Cardiol. 2017;69:1095–1096. doi:
entific, and Bioexcel; proctorshop fees from Bioexcel and Boston Scientific. Dr 10.1016/j.jacc.2016.12.017
Lombardi: Speaking fees, honoraria, and travel expense reimbursement from 9. Bruckel JT, Jaffer FA, O’Brien C, Stone L, Pomerantsev E, Yeh RW. Angina
Boston Scientific, Asahi-Intecc, Teleflex, Siemens, and Abbott Vascular; equity severity, depression, and response to percutaneous revascularization in
holder in Corindus Vascular Robotics; spouse employed by Phillips. Dr Nicholson: patients with chronic total occlusion of coronary arteries. J Invasive Car-
Advisory boards and consulting: Abbott Vascular, Boston Scientific, Medtronic, diol. 2016;28:44–51.
and Corindus. Dr Olivecrona: Lecture/proctor honoraria: Biotronik, EPS vascu- 10. Werner GS, Ferrari M, Heinke S, Kuethe F, Surber R, Richartz BM, Figulla HR.
lar, Biosensors, and Edwards Lifesciences. Dr Postu: Advisory board: Medtronic; Angiographic assessment of collateral connections in comparison with inva-
proctor: Boston Scientific; consultant: Terumo. Dr Quadros: Education support sively determined collateral function in chronic coronary occlusions. Circula-
from Medtronic, Abbott Vascular, Boston Scientific, and Biotronic, and research tion. 2003;107:1972–1977. doi: 10.1161/01.CIR.0000061953.72662.3A
grants from Medtronic. Dr Quesada: Proctor for Boston Scientific. Dr Saghat- 11. Sachdeva R, Agrawal M, Flynn SE, Werner GS, Uretsky BF. The myocar-
elyan: Consulting/speaker honoraria from Asahi Intecc. Dr Trinidad: Proctor dium supplied by a chronic total occlusion is a persistently ischemic zone.
and Speaker for Boston Scientific and Abbott Vascular. Dr Smith: Speaker fees, Catheter Cardiovasc Interv. 2014;83:9–16. doi: 10.1002/ccd.25001
honoraria, proctorship fees, Boston Scientific, Abbott Vascular, Vascular Perspec- 12. Galassi AR, Boukhris M, Toma A, Elhadj Z, Laroussi L, Gaemperli O,
tives, and Biosensors International. Dr Stone: Reports having served as a con- Behnes M, Akin I, Lüscher TF, Neumann FJ, et al. Percutaneous coronary
sultant to: Matrizyme, Miracor, Neovasc, V-wave, Shockwave, Valfix, TherOx, intervention of chronic total occlusions in patients with low left ventricu-
Reva, Vascular Dynamics, Robocath, HeartFlow, Gore, Ablative Solutions, and lar ejection fraction. JACC Cardiovasc Interv. 2017;10:2158–2170. doi:
Ancora; having received speaker honoraria from Amaranth and Terumo; holding 10.1016/j.jcin.2017.06.058
equity in Ancora, Cagent, Qool Therapeutics, Aria, Caliber, MedFocus family of 13. Megaly M, Saad M, Tajti P, Burke MN, Chavez I, Gössl M, Lips D,
funds, Biostar family of funds, Applied Therapeutics, and SpectraWAVE; serv- Mooney M, Poulose A, Sorajja P, et al. Meta-analysis of the impact of
ing as a director in SpectraWAVE; and that his employer, Columbia University, successful chronic total occlusion percutaneous coronary intervention on
receives royalties for sale of the MitraClip from Abbott. Dr Strange: Consulting left ventricular systolic function and reverse remodeling. J Interv Cardiol.
fees from Abbott and Boston Scientific. Dr Tammam: Proctor for Boston Scien- 2018;31:562–571. doi: 10.1111/joic.12538
tific, Terumo and Asahi. Dr Ungi: CTO Proctor and consultant for Boston Scien- 14. Henriques JP, Hoebers LP, Råmunddal T, Laanmets P, Eriksen E, Bax M,
tific. Dr Vo: Consultant for Abbott Vascular, Canadian Hospital Specialties, and Ioanes D, Suttorp MJ, Strauss BH, Barbato E, et al; EXPLORE Trial In-
Teleflex. Dr Wollmuth: Proctor/consultant for Abbott Vascular, Boston Scientific, vestigators. Percutaneous intervention for concurrent chronic total oc-
and Asahi Intecc. Dr Wu: Consultant fees and speaker honorarium from Abbott
clusions in patients with STEMI: the EXPLORE Trial. J Am Coll Cardiol.
and Boston Scientific, and research grant from Asahi. Dr Wyman: Consultant/
2016;68:1622–1632. doi: 10.1016/j.jacc.2016.07.744
honoraria from Abbott, Abiomed, and Boston Scientific. Dr Yeh: Consulting/
15. Mashayekhi K, Nührenberg TG, Toma A, Gick M, Ferenc M, Hochholzer W,
advisory board: Abbott Vascular, Asahi Intecc, Boston Scientific, Medtronic, and
Comberg T, Rothe J, Valina CM, Löffelhardt N, et al. A randomized trial to
Teleflex. Research grants: Abbott Vascular, Abiomed, and Boston Scientific. Dr
assess regional left ventricular function after stent implantation in chronic
Rinfret: Research support from SoundBite Medical; consultant, proctor and/or
total occlusion: the REVASC Trial. JACC Cardiovasc Interv. 2018;11:1982–
speaker for Abiomed, Boston Scientific, Abbott, and Teleflex. The other authors
1991. doi: 10.1016/j.jcin.2018.05.041
report no conflicts.
16. Nombela-Franco L, Mitroi CD, Fernández-Lozano I, García-Touchard A,
Toquero J, Castro-Urda V, Fernández-Diaz JA, Perez-Pereira E, Beltrán-

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Circulation

Guiding Principles for Chronic Total Occlusion

ABSTRACT: Outcomes of chronic total occlusion (CTO) percutaneous Emmanouil S. Brilakis,

grade approach are all complementary and necessary crossing strate-

© 2019 American Heart Association, Inc.

420 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

roCTO multicenter trial (A Randomized Multicentre Trial

Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797 July 30, 2019 421

coronary artery disease.16,17 and a higher frequency

With Myocardial Ischemia; NCT03563417) and the

422 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

ommended as primary strategy.

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424 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

CTO CROSSING STRATEGIES

antegrade direction (original direction of blood flow).

Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797 July 30, 2019 425

Figure 2. Illustration of the chronic total occlusion crossing techniques.

426 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

Study Technical Procedural Overall Acute

Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797 July 30, 2019 427

OPTIMAL STENT DEPLOYMENT MD; Stephane Rinfret, MD, SM

CTO-PCI often involves placement of multiple stents in Correspondence

CONCLUSIONS (L.B.). Department of Cardiology, Heartcentre Niederrhein, Helios Clinic Krefeld,

428 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797 July 30, 2019 429

Toquero J, Castro-Urda V, Fernández-Diaz JA, Perez-Pereira E, Beltrán-

430 July 30, 2019 Circulation. 2019;140:420–433. DOI: 10.1161/CIRCULATIONAHA.119.039797

STATE OF THE ART

Noguchi Y, Kato K, Shibata Y, et al. Impact of J-CTO score on procedural

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coronary chronic total occlusions. Int J Cardiol. 2017;231:78–83. doi:

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