World Journal of Cardiovascular Diseases, 2013, 3, 536-542 WJCD Published Online December 2013 (
Chronic total occlusions for intermediate volume
operators: An antegrade step-up algorithm allows high
success in easy and intermediate difficult CTO lesions
Joren Maeremans1, Philippe Selleslagh2, Luigi Di Serafino3, Emanuele Barbato3, Joseph Dens2
1Faculty of Medicine and Life Sciences, Hasselt University, Diepenbeek, Belgium
2Department of Cardiology, Ziekenhuis Oost-Limburg, Genk, Belgium
3Department of Cardiology, Onze-Lieve-Vrouw Ziekenhuis, Aalst, Belgium
Received 17 October 2013; revised 21 November 2013; accepted 1 December 2013
Copyright © 2013 Joren Maeremans et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In accor-
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To improve the success rates of chronic total occlusion
(CTO) intervention, a large range of CTO-dedicated
guidewires (GWs), devices and techniques have been
developed. However, such an abundant choice of ma-
terials confuses inexperienced operators. Therefore,
the usefulness of a simple antegrade treatment algo-
rithm with a limited set of GWs, for easy to interme-
diate lesions, was investigated. Between November
2011 and March 2013, 105 patients were included,
who underwent CTO PCI following the algorithm.
Lesions were classified according to the Multicenter
CTO Registry of Japan score. Overall technical suc-
cess was achieved in 77%. Study endpoint was suc-
cessful GW crossing within 30 min and was reached
in 57%. High success rates were achieved in easy
(81%) and intermediate (64%) lesion types. In both
types, a soft wire could successfully cross in 57% and
51% respectively, with the Fielder XT® (Asahi Intecc
Co.) capable of crossing most commonly (90%). The
proposed treatment algorithm simplifies the percuta-
neous treatment of easy to intermediate CTO lesions.
However, it merits further evaluation, especially for
operators/centers who perform a low to intermediate
amount of CTO PCI.
Keywords: Percutaneous Coronary Intervention;
Chronic Total Occlusion; Interventional Cardiology;
Coronary Angioplasty; Guidewires
Currently, in 15% - 30% of all coronary angiograms
performed in patients with single or multivessel coro-
nary artery disease, at least one coronary chronic total
occlusion (CTO) is present [1-3]. In non-randomized
trials, successful recanalization of these CTOs has shown
to improve survival, cardiac function and overall quality
of life [2,4-7]. Nevertheless, 40% of these patients are
treated medically or a large portion of these patients is
referred for coronary artery bypass grafting (CABG)
surgery, especially those with multivessel disease and a
high syntax-score [3]. This reluctance to perform percu-
taneous coronary intervention (PCI) has historically been
driven mainly by anatomical factors, related to the CTO.
Because of these, several technical difficulties often arise
during the interventional procedure, most commonly the
crossing of the guidewire (GW) into the distal true lumen
of the artery [4,6].
A large range of CTO-dedicated GWs and devices have
been developed to reduce treatment failure rates. How-
ever, such an abundant choice of GW types, all with spe-
cific characteristics (polymer-coated vs. non-coated;
jacket vs. sleeve coatings; spring vs. non-spring coil; low
vs. high tip load; …) confuses the operator, being unable
to build up sufficient experience with one type or set of
wires, especially in low or intermediate PCI volume
centers. Besides GWs, complex algorithms, including
retrograde and hybrid approaches, have also been devel-
oped by experienced operators. Unfortunately, these
complex techniques will not be applied by low or inter-
mediate volume operators, resulting in reluctance to
tackle the CTO lesion. Therefore, a simple step-up ap-
proach with the new generation of wires and micro-
catheters might result in reduced failure rates in easy
CTO lesions and those with intermediate difficulty.
The present study investigated the usefulness of such a
J. Maeremans et al. / World Journal of Cardiovascular Diseases 3 (2013) 536-542 537
simple antegrade treatment algorithm with a limited set
of GWs to treat CTOs, especially easy and intermediate
difficult lesions. Having a pragmatic and structured ap-
proach to simpler lesions may also encourage less ex-
perienced operators to treat more CTOs via PCI with
higher success rates. Procedural success was defined as
successful GW crossing within 30 minutes, since GW
crossing is often the limiting factor for general proce-
dural success and because other factors such as opera-
tor’s skill, experience, judgment and perseverance can
influence general procedural outcome. CTOs were cate-
gorized according to the Multicenter CTO Registry of
Japan (J-CTO) scoring criteria, developed by Morino et
al. [8], to assess the success rates related to angiographic
characteristics. The results of this study were compared
with those of Fujino et al. and the European Registry of
Chronic Total Occlusion (ERCTO) (Galassi et al.) [9,10].
2.1. Study Population
Between November 2011 and March 2013, a Belgian
two-center, non-randomized, prospective registry was
conducted in the hospitals of Genk (ZOL) and Aalst
(OLVZ), with permission to collect data by the institu-
tional research ethics boards. Patients included in the
study have given informed consent to collect data. Both
centers perform 1200 - 1500 PCIs and 40 to 70 CTO
procedures a year. Different operators perform CTO-
procedures, but the majority of these are executed by two
operators (one in each center). CTO procedure data were
collected prospectively in 108 consecutive patients. Pa-
tients were selected for CTO PCI based on their clinical
symptoms, left ventricular viability and/or documented
ischaemia. Baseline demographics, angiographic charac-
teristics, procedural characteristics and outcomes were
analyzed. For the purpose of the analysis, the data of
those patients, in whom the applied algorithm (cfr.
“step-up strategy”) was followed, were used (105 pa-
tients). CTOs treated by the retrograde approach were
excluded. CTOs were categorized according to the J-
CTO criteria [8]. Four groups were created, based on the
difficulty of the CTO lesion (easy (0), intermediate (1),
difficult (2) and very difficult (3)). The difficulty cor-
responds to the amount of negative angiographic charac-
teristics of the CTO lesion (“blunt type at the entry site”,
“bending (45˚)”, “calcification”, “occlusion length (20
mm)” and/or “previously failed lesion”).
2.2. Definitions
A CTO was defined as a lesion of a native coronary ar-
tery which exhibited Thrombosis in Myocardial Infarc-
tion (TIMI) antegrade flow 0 and which was present for
at least 3 months. Angiographic characteristics were de-
fined as reported by Morino et al. [8]. To estimate the
length of the occlusion, in these lesions with retrograde
filling from the opposite artery, an angiogram per-
formed by bilateral arterial approach and the length of
the first PCI-balloon crossing the lesion was used. Oc-
clusion length was then categorized as <20 or 20 mm,
as described by the EuroCTOClub [11].
As an endpoint for this study, GW manipulation time
was used, as did Morino et al. [8]. This is the time from
initial insertion of the GW into the coronary artery to the
time of successful crossing or being pulled out because
of failure. To categorize this numerical variable, a 30
minutes cutoff value was set as a threshold for successful
GW crossing.
2.3. Step-Up Strategy
The antegrade step-up algorithm, which is mainly in-
tended for easy to intermediate difficult lesions, is as
follows (Figure 1, Table 1): unless the CTO-lesion is
ostial or post-ostial, a microcatheter (Finecross® (Te-
rumo Interventional Systems) or Corsair® (Asahi Intecc
Co.)) is delivered over a soft wire (Figure 2). The soft
wire is exchanged for a Fielder XT® or FC® (Asahi In-
tecc Co.) wire (Figure 3). This technique allows a
Figure 1. Algorithm for crossing chronic total oc-
Table 1. Overview of applied guidewires during PCI, based on
guidewire tip load.
Soft wires
(<3 g)
Intermediate stiff wires
(3 - 6 g)
Stiff wires
(>6 g)
Fielder XT*
Fielder FC*
Miracle 3, 4.5, 6*
Progress 40**
Progress 120/140T**
Progress 200T**
*Asahi Intecc Co.; **Abbott Vascular.
Copyright © 2013 SciRes. OPEN ACCESS
J. Maeremans et al. / World Journal of Cardiovascular Diseases 3 (2013) 536-542
Copyright © 2013 SciRes.
Figure 2. Structure of Finecross® (Terumo Interventional Systems) and Corsair® (Asahi Intecc Co.) microcatheters.
Figure 3. Structure of Fielder XT® (Asahi Intecc Co.) and Progress 40® (Abbott Vascular) guidewires.
J. Maeremans et al. / World Journal of Cardiovascular Diseases 3 (2013) 536-542 539
specific shape of the tip of the dedicated CTO wire.
Fielder XT® and FC® are defined as soft wires, based on
the low tip load of these wires. Upon failure, a GW ex-
change to an intermediate stiff wire was made. Follow-
ing the algorithm, this second wire is a Miracle® 3/4.5/6
(Asahi Intecc Co.) or Progress 40® (Abbott Vascular).
During the registry, the UltimateBros3® (Asahi Intecc
Co.) became available which replaced the Miracle® as
the wire of preference. If unsuccessful, exchange to-
wards even more stiff wires was performed, with the
Confianza® (Pro) (Asahi Intecc Co.), Progress® 120,
140T and 200T (Abbott Vascular) as preferred wires. In
both centers the wire of preference to start with was the
Fielder XT® wire.
2.4. Guidewires
The Fielder XT® is a soft and tapered GW with a tip load
and diameter of respectively 0.8g and 0.009" (Figure 3).
The outer diameter is 0.014". It has a stainless steel
spring coil core, with a hydrophilic polymer sleeve coat-
ing at the distal end of the wire which provides lubricity
and trackability for tortuous vessels. A PTFE-coating
covers the shaft of the wire. The Fielder FC® has similar
characteristics as the Fielder XT® but is not tapered and
its polymer sleeve is a bit longer. The Miracle® 3/4.5/6
and UltimateBros3® GWs are both intermediate stiff
GWs with tip loads between 3 and 6 g. The core wire and
distal coil are designed to resist great force. The higher
tip load increases driving force against tight lesions. The
UltimateBros3® has a longer hydrophilic polymer coat-
ing which maintains high maneuverability, allowing im-
proved wire manipulation in tight lesions. The Confi-
anza® GW has a tapered tip diameter of 0.009" and a
non-hydrophilic coating. In combination with its heavy
tip load, highly resistant lesions can be penetrated. The
Progress®-family is a family of CTO wires coated with a
lubricious, hydrophilic sleeve coating (Figure 3). As a
core, these wires have DURASTEEL® and both the outer
and tip diameter is 0.014”. This family has different tip
loads resulting in a range of tip stiffness.
2.5. Statistical Analysis
Univariate analyses were performed to assess the rela-
tionship between the patients’ baseline and angiogra-
phic characteristics and successful GW crossing within
30 minutes. Numerical values were expressed as mean ±
standard deviation, while categorical variables were ex-
pressed as percentage of total. Normality was assessed
using the Shapiro-Wilk statistic. Comparisons between
groups were performed using Fisher’s exact test for
categorical variables and the independent Student’s t-test
for continuous variables, with the level of significance
set at p 0.05. Data on procedural characteristics and
procedural success rates were also calculated for the dif-
ferent J-CTO difficulty groups. In addition, a subdivision
was made according to the applied treatment algorithm.
All statistical analyses were carried out using SPSS Sta-
tistics version 20 (IBM SPSS Inc.).
3.1. Study Population, Overall Results and
Procedural Characteristics
The algorithm was followed in 105 out of 108 patients
(97.2%). In 81 of these patients, general success was
achieved (77.1%) (Table 2). Lesions were categorized
into difficulty risk groups (easy, intermediate, difficult
and very difficult), according to the J-CTO scoring
model [8]. In this way, respectively 21, 42, 28 and 14
patients were assigned to each group. In 83.8% of all
lesions, a microcatheter was used. Overall success was
achieved in 90.5%, 81%, 82.1% and 35.7% of each
group respectively. For each risk group, procedural cha-
racteristics were evaluated (Table 2). This includes the
number of wires used, procedure times, fluoroscopy
times, contrast use and radiation doses. An increase in
these values is seen in accordance with lesion difficulty.
The values in the very difficult group do not differ signi-
ficantly from the difficult, due to abortion of the proce-
dure by the operator, if it seemed futile to continue. Ne-
vertheless, these values are relatively low and clearly
within safety margins for contrast use and radiation ex-
The primary endpoint of this study was successful GW
crossing within 30 minutes. The baseline characteristics
as well as angiographic characteristics and procedural
outcomes of the study population, classified according to
this primary endpoint, are reported in Table 3. No sig-
nificant differences were present between the two groups
for baseline characteristics except for age (62.9 ± 10.9 vs.
67.4 ± 9.5, p = 0.03). Concerning angiographic charac-
teristics, the failure rate to cross within 30 minutes was
clearly higher if the shape of the entry site was blunt
(10.0% vs. 40.0%, p = 0.000) and when calcifications
were present (28.3% vs. 57.8%, p = 0.003). Other an-
giographic characteristics were not significantly different,
although this might be due to the sample size.
3.2. Successful Guidewire Crossing and Step-Up
In 57% of all patients, the primary endpoint of suc-
cessful GW crossing within 30 minutes was achieved
(Table 4). According to the model of Morino et al. [8],
the primary endpoint was achieved in 17 (81%), 27
(64%), 13 (46%) and 3 (21%) cases respectively.
In total, 43% of 94 CTO lesions could be crossed
within 30 minutes by using only soft wires. In 95% of
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J. Maeremans et al. / World Journal of Cardiovascular Diseases 3 (2013) 536-542
Table 2. Overall success and mean procedural characteristics according to J-CTO risk groups.
Total Easy Intermediate Difficult Very difficult
N˚ of patients (n) 105 21 42 28 14
Overall success (n (%)) 81 (77.1%) 19 (90.5%) 34 (81.0%) 23 (82.1%) 5 (35.7%)
Procedure time (min)* 90 ± 50 86 ± 42 85 ± 49 97 ± 52 97 ± 60
Radiation dose (mGy)* 1949 ± 876 1328 ± 602 1979 ± 958 2132 ± 786 2214 ± 815
Contrast (ml)* 304 ± 128 296 ± 79 307 ± 110 320 ± 181 279 ± 120
Fluoroscopy time (min)* 31 ± 24 23 ± 10 29 ± 17 39 ± 38 32 ± 14
N˚ of wires used (n) 3.54 ± 1.77 2.95 ± 1.47 3.40 ± 1.64 3.86 ± 1.76 4.21 ± 2.29
Procedural values are expressed as mean ± SD. *2, 37, 3 and 4 missing values were reported for procedure time, radiation dose, contrast and fluoroscopy time
Table 3. Baseline and angiographic characteristics, according
to successful guidewire crossing within 30 minutes.
Variable Successful (n = 60) Failure (n = 45)p Value
Age 62.9 ± 10.9 67.4 ± 9.5 0.03
Male 75.0% 82.2% 0.5
BMI* 29.4 ± 5.2 28.5 ± 4.2 0.4
SBP 136 ± 26.7 136 ± 22.0 1.0
DBP 73.7 ± 11.6 72.1 ± 11.9 0.5
EF 61.7 ± 14.9 62.7 ± 10.6 0.7
Current smoker 38.3% 28.9% 0.5
Hypertension 53.3% 53.3% 1.0
Dyslipidemia 78.3% 64.4% 0.13
Diabetes 28.3% 28.9% 1.0
Prior MI 26.7% 24.4% 0.8
Prior PCI 33.3% 37.8% 0.7
Prior CABG 15.0% 15.6% 1.0
Prior PVD 28.3% 28.9% 1.0
Prior CVD* 9.3% 7.0% 1.0
MVD 50.0% 53.3% 0.8
Target lesion RCA
% Presence of negative characteristics/lesion
Previously failed lesion 8.3% 13.3% 0.5
Blunt stump type
at entry 10.0% 40.0%
Bending > 45˚ 13.3% 15.6% 0.8
Calcification 28.3% 57.8%
Occlusion length 20
mm 43.3% 51.1% 0.4
Bridging collaterals 31.7% 15.6% 0.07
Side-branch < 5 mm
from prox. cap 61.7% 71.1% 0.4
Rentrop class
(grade = 3) 51.7% 55.6% 0.9
Values are expressed as % or mean ± SD. *12 and 8 missing values were
reported for BMI and CVD respectively. BMI = body mass index; CABG =
coronary artery bypass grafting; CVD = cerebrovascular disease (CVA/TIA);
CX = circumflex artery; DBP = mean diastolic blood pressure; EF = ejection
fraction; LAD = left anterior descending artery; MI = myocardial infarction;
MVD = multivessel disease; PCI = percutaneous coronary intervention;
PVD = peripheral vascular disease; RCA = right coronary artery; SBP =
mean systolic blood pressure.
these cases, the Fielder XT® (Asahi Intecc Co.) was ca-
pable of crossing the lesion. According to lesion diffi-
culty, the success rate with a soft wire was 57% (12/21
lesions) for the easy group and 51% (20/39) for the in-
termediate lesions. A Fielder XT® was capable of cro-
ssing in 92% and 95% of these groups respectively. For
the difficult and very difficult groups, the success rate
with only a soft wire was 24% (5/21) and 23% (3/13)
respectively. Following the step-up strategy, lesions
which failed to be crossed with a soft wire were at-
tempted by an intermediate wire and/or stiff wire. How-
ever, not in all the lesions additional wire escalation was
performed, due to sub-intimal dissection and/or in the
operator’s judgement further attempts would be futile.
The number of wires used and the additional success
rates with these wires are presented in Table 4.
In the data presented here, only 2 non-ST segment
elevation myocardial infarctions (non-STEMI) occurred
in the hospital of Genk. Besides this, no death, Q-wave
myocardial infarction (MI) or pericardial effusion need-
ing drainage occurred during the procedures.
To date, several papers address the use of different CTO
devices and techniques. They represent the results of
operators who are highly experienced in CTOs, per-
forming more than 100 CTO procedures/year. Often they
report on high success rates in both easy and difficult
lesions, using different guidewires, devices and complex
techniques, including retrograde and hybrid approaches
[12,13]. However, in general more CTO procedures are
still performed by less experienced operators, for whom
these techniques are not directly applicable, especially in
low or intermediate volume centers. Therefore, a simple
antegrade step-up algorithm for easy and intermediate
difficult CTOs still is worthwhile to be adapted.
This was investigated in a prospective study of 105
consecutive CTO procedures, performed in two interme-
diate volume CTO centers. The algorithm is based on the
development of second generation dedicated CTO-wires
(Fielder®, Miracle®, UltimateBros3®, Confianza® (Asahi
Copyright © 2013 SciRes. OPEN ACCESS
J. Maeremans et al. / World Journal of Cardiovascular Diseases 3 (2013) 536-542 541
Table 4. Successful guidewire crossing within 30 minutes, according to J-CTO difficulty groups and applied step-up strategy.
Total Easy Intermediate Difficult Very difficult
N˚ of patients (n) 105 21 42 28 14
Successful crossing 30 minutes 57% (60/105) 81% (17/21) 64% (27/42) 46% (13/28) 21% (3/14)
Success with soft wires 43% (40/94ε) 57% (12/21) 51% (20/39*) 24% (5/21Δ) 23% (3/13γ)
Additional success with intermediate wires 37% (15/41) 60% (3/5) 54% (7/13) 33% (5/15) 0% (0/8)
Additional success with stiff wires 19% (5/27) 66% (2/3) 0% (0/7) 17% (3/10) 0% (0/7)
*3/42 lesions were treated immediately with an intermediate stiff wire; Δ7/28 lesions were treated immediately with an intermediate stiff wire; γ1/14 lesions was
treated with immediately with a stiff wire; εIn total 11 lesions were not treated with a soft wire.
Intecc Co.) and the Progress®-family (Abbott Vascular)),
allowing operators to get familiar with a limited set of
wires. With the use of this set of dedicated CTO-wires
and the routine use of a microcatheter, this algorithm
should simplify procedures.
In this study, GW manipulation time was used as the
endpoint for success [8]. This was done because suc-
cessful GW crossing is most often the limiting factor for
general procedural success. Consequently, the J-CTO
scoring model was used to categorize the lesions accord-
ing to difficulty [8]. The overall success rate with the
applied algorithm was 77.1%, while it was possible to
cross the lesion within 30 minutes in 57%. For each risk
group, similar success rates are achieved for this primary
endpoint (81%, 64%, 46% and 21% respectively), com-
pared to those of Morino et al. (derivation set: 87.7%,
67.1%, 42.4%, 10% and validation set: 92.3%, 58.3%,
34.8%, 22.2% respectively) [8]. We routinely used a mi-
crocatheter as back-up to increase wire tip load and sup-
port. These results confirm that the technique works well
in easy to intermediate type of CTO lesions and that for
more difficult lesions, one needs different materials,
techniques and experience to be successful.
In 43% of all cases, soft wires were able to cross the
lesion within 30 minutes, 95% of these lesions were
crossed with the Fielder XT®. Moreover, when looking
at the “easy” and “intermediate” lesions, a success rate of
up to 57% and 51% was achieved, with the Fielder XT®
capable of crossing in 92.5% and 95% of the cases re-
spectively. This result is similar to the findings of Fujino
et al. [10]. They reported a success rate of 37% for pa-
tients treated only with a single soft wire (Fielder
XT®/XT-R®). However, general success in all types of
lesions was used as endpoint in this study. Besides this,
Galassi et al. reported a slightly lower success rate
(29.2% vs. 43%). 36% of these were successfully crossed
with a Fielder XT®, which is clearly lower than in our
study, due to different lesion selection [9].
From the results of this study, using a step-up algorithm,
in which a pre-defined set of new generation CTO-
dedicated wires is used, high success rates in easy and
intermediate type of lesions can be obtained. In particular
the use of a Fielder XT® as a wire of first choice simpli-
fies the procedure. The additional benefit is the overall
limited number of wires, fluoroscopy, contrast, proce-
dure time and radiation, reducing costs and increasing
safety. We therefore strongly encourage less experienced
and intermediate volume operators/centers to follow a
treatment algorithm, in which a select set of CTO-
dedicated guidewires is used, to get familiar with. The
presented algorithm can serve as a guideline for this,
especially in the case of so called easy CTOs and those
of intermediate difficulty. For more difficult lesions (i.e.
J-CTO score of 3), which are less easy to deal with, an
onward referral to an expert CTO center should be con-
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