The document describes a study examining the use of polymer-jacketed, tapered-tip, low-force guidewires with composite-core and dual-coil design (Fielder XT-R and XT-A wires) for the antegrade approach to chronic total occlusion percutaneous coronary interventions. 164 consecutive CTO lesions treated at a single institution using the Fielder wires as the starting wire were analyzed. Technical success rates using the Fielder wires antegrade were 79%, 60%, and 17% for lesions with J-CTO scores of 0-1, 2-3, and 4-5 respectively. Successful antegrade cases had median wiring times of 6.5 to 12 minutes depending on J-

1. ORIGINAL CONTRIBUTION
Vol. 32, No. 5, May 2020 161
The initial approach to chronic total occlusion
(CTO) intervention has become dichotomized into
the North American hybrid algorithm putting less
emphasis on soft tissue tracking and antegrade wire esca-
lation (AWE) vs the Asia-Pacific algorithm that strongly
favors an antegrade-first philosophy.1,2
As the limitations
of early CTO wires (non-tapered tips, stiffness, and lack
of steerability) pushed operators to alternative approach-
es, recent advances in wire technology, as embodied by the
composite-core design of the Fielder XT-R and XT-A
(XTRA) wires (Asahi Intecc), have made the antegrade ap-
proach more efficient, safe, and feasible.3,4
Both the Euro
CTO Club and the Asia-Pacific CTO Club recommend the
Fielder XT-R wire as the initial choice for antegrade CTO
wiring.1,3
Following the availability of XTRA wires in the
United States, our center migrated toward an Asia-Pacific
approach to CTO interventions. In this report, we describe
our initial experience in terms of procedural outcomes,
efficiency, and safety using the XTRA wires in a North
American population employing an AWE primary crossing
strategy irrespective of angiographic lesion characteristics.
Methods
This was an investigator-initiated retrospective study with
no formal industry funding. A total of 155 unique patients
and 164 unique CTO lesions were included in the analysis.
The cohort represents all CTO procedures performed by
dedicated CTO operators at the Cleveland Clinic in Cleve-
land, Ohio from March, 2017 to December, 2018. During
this time, the institutional practice was to begin all CTO
cases antegrade (regardless of lesion characteristics) by ap-
proaching the CTO with a workhorse wire and microca-
theter, then exchanging for a Fielder XT-R or XT-A for
initial lesion engagement. Therefore, this cohort represents
a non-selected series of consecutive CTO patients treated
during this period. The study was approved by the institu-
tional review board of the Cleveland Clinic.
Definitions. Coronary CTO was defined as a coronary
lesion with Thrombolysis in Myocardial Infarction (TIMI)
flow grade 0 of at least 3-month duration as estimated by
the primary operator based on clinical history and angio-
graphic appearance. Calcification was defined as mild (min-
imal spots on angiography), moderate (≤50% of reference
Use of Polymer-Jacketed,Tapered-Tip, Low-Force
Guidewires With Composite-Core, Dual-Coil Design as
Part of the Antegrade Approach to Coronary
Chronic Total Occlusions
Jeffrey E. Rossi, MD; Ravi Nair, MD; Stephen G. Ellis, MD; Samir R. Kapadia, MD; Jaikirshan J. Khatri, MD
ABSTRACT: Aims. To investigate the impact of novel, polymer-jacketed, tapered-tip, low-force guidewires with compos-
ite-core, dual-coil design (Fielder XT-R and Fielder XT-A; Asahi Intecc) on antegrade wire escalation (AWE) crossing of coro-
nary chronic total occlusion (CTO) lesions. Methods. From March of 2017 to December 2018, a total of 164 consecutive CTO
lesions at a single institution were treated with a primary AWE strategy using either Fielder XT-R or XT-A (XTRA) as the starting
wire regardless of lesion characteristics. Success rates, wiring times, and complications were analyzed. Results. The mean
Japanese (J)-CTO score was 3.71 ± 1.27, mean PROGRESS-CTO score was 2.46 ± 1.15, and mean PROGRESS-CTO Complications
score was 3.9 ± 2.0. Mean CTO length was 25.0 ± 0.5 mm, 48 lesions (29.3%) were previously bypassed, 77 lesions (47.0%) had
moderate to severe calcification, and 62 lesions (37.8%) had moderate to severe tortuosity. Antegrade success rates using
XTRA wires were 79%, 60%, and 17% of lesions with J-CTO scores of 0-1, 2-3, and 4-5, respectively. In successful antegrade
XTRA cases, median wiring times were 6.5 min (interquartile range [IQR], 5.0-11.0 min), 9.0 min (IQR, 4.2-14.0 min), and 12.0 min
(IQR, 9.0-15.0 min) for J-CTO scores of 0-1, 2-3, and 4-5, respectively, and differed non-significantly according to J-CTO score
(P=.20). Complication rates were low (In-hospital major adverse cardiac event rate, 1.3%) with no wire perforations caused by
XTRA wires. Conclusions. Use of Fielder XTRA wires as part of an AWE strategy in CTO percutaneous coronary interventions
may facilitate more efficient antegrade lesion crossing and overall procedural success in lesions that have been traditionally
challenging to treat using an antegrade-first approach.
J INVASIVE CARDIOL 2020;32(5):161-168.
KEY WORDS: chronic occlusions, chronic total occlusions, CTO
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2. Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
162 The Journal of Invasive Cardiology®
lesion diameter), or severe (≥50% of reference lesion di-
ameter). Tortuosity was defined as straight (<70°, 1 bend),
mild (>70°, 1 bend), moderate (2 bends >70° or 1 bend
>90°), or severe (2 bends >90° or 1 bend >120°). Tapered
stump was defined as a funnel-shaped origin of the proximal
lesion cap. Interventional collaterals were defined as collateral
vessels deemed amenable to crossing with a guidewire and
microcatheter. Good distal landing zone was defined as a distal
vessel ≥2.0 mm in diameter without diffuse disease. Good
distal opacification was defined as similar to the proximal ves-
sel and faint distal opacification as less than the proximal vessel.
Wiring time was defined as time from initial workhorse wire
insertion into the CTO vessel to the time of crossing the
lesion into the distal true lumen. If multiple CTO lesions
were attempted during a single procedure, only the first
CTO lesion for wiring time was counted.The Multicenter
CTO Registry in Japan (J-CTO) score was calculated as
described by Morino et al.5
The recommended primary
crossing strategy per the hybrid algorithm was determined
using the flow chart created by Michael et al.6
A lesion
had to satisfy all three retrograde criteria to be classified as
recommended for a primary retrograde approach. Lesions
not meeting these criteria and with length ≥20 mm were
classified as recommended for a primary antegrade dissec-
tion and re-entry (ADR) approach. All other lesions were
classified as recommended for a primary AWE approach.
Technical success was defined as successful CTO recanaliza-
tion with achievement of <30% residual stenosis and TIMI
3 flow. In-hospital major adverse cardiac event (MACE) rate was
defined as a composite of death, myocardial infarction (MI),
target-vessel revascularization, tamponade requiring peri-
cardiocentesis or surgery, and stroke. Acute MI was defined
using the fourth universal definition of MI (type 4a MI).7
A
small hematoma was defined as <5 cm, and a large hematoma
as ≥5 cm.
Statistical analysis. Categorical variables are expressed as
number and percentage, and continuous variables as mean ±
standard deviation or median with interquartile range (IQR)
for non-normally distributed variables.Wiring time trends per
J-CTO score were compared using a Spearman’s rank correla-
tion test.Wiring times by hybrid algorithm proposed strategy
were compared using the Kruskal-Wallis test. Success rates
were compared using a Chi-square test.All statistical analyses
were performed with R version 3.4.1 in R-studio environ-
ment, version 1.1.463 (R Foundation for Statistical Comput-
ing).A 2-sided P-value ≤.05 was considered to indicate statis-
tical significance.
Results
Patient clinical and angiographic characteristics.
A total of 155 patients and 164 CTO lesions treated with a
primary AWE strategy using XTRA were analyzed. Baseline
clinical characteristics are summarized in Table 1.The mean
age was 64 ± 9.6 years, 137 (83.5%) were male, 61 (37.2%)
had prior coronary artery bypass grafting, and 75 (45.7%)
had diabetes. The majority of procedures were performed
for symptom relief (69.5%) and 58.8% of patients had Ca-
nadian Cardiovascular Society class ≥3 angina. The average
ejection fraction was 51.4 ± 13.4%.
Angiographic characteristics are shown inTable 2.Fifty-one
lesions (31.1%) were prior failures, 26 (15.9%) were in-stent
restenoses, and 48 (29.3%) were previously bypassed vessels.
Table 1. Baseline clinical characteristics.
(n = 164)
Age (years) 64.0 ± 9.6
Male 137 (83.5%)
Caucasian 149 (92.0%)
Body mass index (kg/m2
) 31.7 ± 6.7
Smoking within past year 25 (15.2%)
Diabetes 75 (45.7%)
Dyslipidemia 155 (94.5%)
Hypertension 145 (88.4%)
Prior percutaneous coronary intervention 103 (62.8%)
Prior coronary artery bypass grafting 61 (37.2%)
Prior myocardial infarction 70 (42.7%)
Atrial fibrillation 27 (16.5%)
Dialysis 4 (2.4%)
Cerebrovascular disease 12 (7.3%)
Peripheral arterial disease 19 (11.6%)
Lung disease 23 (14.0%)
Creatinine (mg/dL) 1.3 ± 1.2
Anemia 50 (30.5%)
Indication
Symptom relief 114 (69.5%)
Reduced ejection fraction 13 (7.9%)
Arrhythmia 12 (7.3%)
Ischemia reduction 11 (6.7%)
Acute coronary syndrome 9 (5.5%)
Staged for complete revascularization 5 (3.0%)
Canadian Cardiovascular Society class
0 20 (12.5%)
1 3 (1.9%)
2 43 (26.9%)
3 83 (51.9%)
4 11 (6.9%)
Dyspnea 120 (73.2%)
Fatigue 117 (71.3%)
Ejection fraction (%) 51.4 ± 13.4
Data presented as mean ± standard deviation or number (%).
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3. Vol. 32, No. 5, May 2020 163
Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
The majority of lesions (41.1%) were in the right coronary
artery. Mean CTO length was 25.0 ± 14.0 mm and mean
vessel diameter was 2.4 ± 0.5 mm. Sixty-four lesions (39.0%)
had an ambiguous proximal cap, 100 (61.0%) had a tapered
stump,77 (47.0%) had moderate to severe calcification,and 62
(37.8%) had moderate to severe tortuosity.The mean J-CTO
score was 3.71 ± 1.27, mean PROGRESS-CTO score was
2.46 ± 1.15, and mean PROGRESS-CTO Complications
score was 3.9 ± 2.0.
Procedural details. Procedural strategy and technical
success are summarized in Table 3.An initial AWE crossing
strategy was employed in all cases. Overall technical success
rate was 84.1%, with 67.7% of lesions crossed antegrade,
12.8% crossed retrograde, and 3.7% crossed using ADR.The
Fielder XT-R was used in 107 cases (52.2%) and Fielder
XT-A was used in 98 cases (59.8%). One hundred cases
(61.0%) were performed using biradial access. The mean
number of guidewires used was 4.2 ± 2.1, the mean number
of microcatheters used was 1.5 ± 0.8, and the mean total
stent length was 53.2 ± 31.8 mm.
Success rates. Technical success rates stratified by
J-CTO score and wire/strategy employed are depicted in
Figure 1. As all cases were started using XTRA wires, the
“any wire antegrade success” column denotes the use of
Table 2. Baseline angiographic characteristics.
(n = 164)
Prior attempt 51 (31.1%)
Prior investment procedure 18 (11.0%)
In-stent restenotic lesion 26 (15.9%)
Ostial 12 (7.3%)
Target vessel
Left anterior descending coronary artery 49 (30.1%)
Left circumflex artery 45 (27.6%)
Right coronary artery 67 (41.1%)
Left main 1 (0.6%)
Other 1 (0.6%)
CTO length (mm) 25.0 ± 14.0
Bypassed vessel 48 (29.3%)
Vessel diameter (mm) 2.4 ± 0.5
Proximal cap ambiguity 64 (39.0%)
Side branch at proximal cap 131 (79.9%)
Stump
Tapered stump 100 (61.0%)
Blunt stump 47 (28.7%)
No stump 17 (10.4%)
Distal opacification
Faint (less than proximal) 73 (44.5%)
Not visible 71 (43.3%)
Good (as proximal) 20 (12.2%)
Distal cap at bifurcation 90 (54.9%)
Good distal landing zone 100 (61.0%)
Collateral side
Contralateral 73 (44.5%)
Ipsilateral 53 (32.3%)
Ipsilateral and contralateral 33 (20.1%)
None 5 (3.0%)
Interventional collaterals 96 (58.5%)
Moderate-severe calcification 77 (47.0%)
Table 2. Baseline angiographic characteristics.
(n = 164)
Moderate-severe tortuosity 62 (37.8%)
Werner grade
0 collateral connections 20 (12.2%)
1 collateral connection 110 (67.1%)
2 collateral connections 34 (20.7%)
Rentrop grade
Grade 0 4 (2.4%)
Grade 1 20 (12.2%)
Grade 2 79 (48.2%)
Grade 3 61 (37.2%)
Japanese-CTO score
0 6 (3.7%)
1 22 (13.4%)
2 45 (27.4%)
3 45 (27.4%)
4 32 (19.5%)
5 14 (8.5%)
PROGRESS-CTO score
0 38 (23.2%)
1 56 (34.1%)
2 34 (20.7%)
3 29 (17.7%)
4 7 (4.3%)
PROGRESS-CTO Complications score
0 34 (20.7%)
1 7 (4.3%)
2 26 (15.9%)
3 39 (23.8%)
4 7 (4.3%)
5 34 (20.7%)
6 17 (10.4%)
Data presented as mean ± standard deviation or number (%).
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4. Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
164 The Journal of Invasive Cardiology®
XTRA plus any additional wires as part of an antegrade
strategy.The “any wire/strategy” column denotes cases start-
ed antegrade with XTRA and eventually crossed using any
wire or advanced strategy (retrograde, ADR). Antegrade
success rates using XTRA were 79% for J-CTO score 0-1,
60% for J-CTO score 2-3, and 17% for J-CTO score 4-5
(P<.001); success rates using any antegrade wire were 89%
for J-CTO score 0-1, 77% for J-CTO score 2-3, and 37% for
J-CTO score 4-5 (P<.001); success rates using any strategy/
wire were 100% for J-CTO score 0-1, 87% for J-CTO score
2-3, and 70% for J-CTO score 4-5 (P<.01). Stratifying by
proposed hybrid algorithm strategy (Figure 2), success rates
for antegrade wiring with XTRA were 74% for a proposed
antegrade strategy, 44% for a proposed ADR strategy, and
24% for a proposed retrograde strategy (P<.001); success
rates for any wire antegrade were 88% for a proposed ante-
grade strategy, 59% for a proposed ADR strategy, and 39%
for a proposed retrograde strategy (P<.001); success rates for
any wire/strategy were 91% for a proposed antegrade strat-
egy, 82% for a proposed ADR strategy, and 76% for a pro-
posed retrograde strategy (P=.25).
Evaluation of success rates in selective subgroups deemed
to be clinically relevant is shown in Figure 3. Success rates
were significantly lower in lesions with moderate/severe cal-
cification,moderate/severe tortuosity,lesion length ≥20 mm,
a non-tapered stump, an ambiguous cap, and with previous
bypass grafts. Success rates were lower in left circumflex le-
sions (40% for left circumflex vs 57% for left anterior de-
scending and 55% for right coronary artery), although the
difference did not reach statistical significance (P=.18).
Wiring times. Wiring times in successful cases are depict-
ed in Figures 4 and 5 andTables 4 and 5. Median wiring time
for XTRA successful antegrade crossing was 6.5 min (IQR,
5.0-11.0 min) for J-CTO 0-1, 9.0 min (IQR, 4.0-14.0 min)
for J-CTO 2-3,and 12.0 min (IQR,9.0-15.0 min) for J-CTO
4-5 (Ptrend
=.20);median time for any wire successful antegrade
crossing was 22.0 min (IQR, 19.5-24.5 min) for J-CTO 0-1,
29.0 min (IQR, 20.5-63.2 min) for J-CTO 2-3, and 18.0
min (IQR, 15.0-26.0 min) for J-CTO 4-5 (Ptrend
=.06); me-
dian time for any wire/strategy successful crossing was 45.0
min (IQR, 37.5-78.5 min) for J-CTO 0-1, 98.0 min (IQR,
46.0-108.0 min) for J-CTO 2-3, and 68.0 min (IQR, 47.0-
111.5 min) for J-CTO 4-5 (Ptrend
<.001).When stratifying by
the proposed hybrid algorithm approach, the median wire
Table 3. Procedural strategies.
(n = 164)
First strategy
Antegrade wiring 164 (100%)
Antegrade dissection and re-entry 0 (0.0%)
Retrograde 0 (0.0%)
Second strategy
Antegrade wiring 0 (0.0%)
Antegrade dissection and re-entry 11 (21.6%)
Retrograde 40 (78.4%)
Third strategy
Antegrade wiring 6 (46.2%)
Antegrade dissection and re-entry 4 (30.8%)
Retrograde 3 (23.1%)
Successful strategy
Antegrade wiring 111 (67.7%)
Antegrade dissection and re-entry 6 (3.7%)
Retrograde 21 (12.8%)
None 26 (15.9%)
Number of strategies (n) 1.4 ± 0.7
Technical success 138 (84.1%)
Investment procedure 8 (7.8%)
Dual injections 124 (76.1%)
Biradial 100 (61.0%)
Radial/femoral 45 (27.4%)
Guide support 30 (18.3%)
Antegrade Fielder XT-R 107 (65.2%)
Antegrade Fielder XT-A 98 (59.8%)
Number of stents (n) 1.8 ± 0.9
Total stent length (mm) 53.2 ± 31.8
Number of guidewires used (n) 4.2 ± 2.1
Number of balloons used (n) 3.3 ± 2.1
Number of microcatheters used (n) 1.5 ± 0.8
Flow in all distal branches restored 126 (81.3%)
Non-CTO lesion treated 33 (20.8%)
Data presented as mean ± standard deviation or number (%).
CTO = chronic total occlusion.
Table 4. Wiring times by J-CTO score.
J-CTO Score 0-1 J-CTO Score 2-3 J-CTO Score 4-5 P-Value*
Wiring strategy
Fielder XT-R/XT-A antegrade crossing 6.5 (5.0-11.0) 9.0 (4.2-14.0) 12.0 (9.0-15.0) .20
Any wire antegrade crossing 22.0 (19.5-24.5) 29.0 (20.5-63.2) 18.0 (15.0-26.0) .06
Any strategy crossing 45.0 (37.5-78.5) 98.0 (46.0-108.0) 68.0 (47.0-111.5) <.001
Data presented as median (interquartile range). *
Spearman rank correlation for trend. CTO = chronic total occlusion.
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5. Vol. 32, No. 5, May 2020 165
Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
crossing times for XTRA successful antegrade crossing were
8.0 min (IQR, 4.5-13.5 min) for proposed antegrade cases,
9.0 min (IQR, 5.0-11.0 min) for proposed ADR cases, and
15.0 min (IQR, 14.8-16.0 min) (P=.10) for proposed retro-
grade cases; median times for any wire successful antegrade
crossing were 22.0 min (IQR, 17.5-31.0 min) for proposed
antegrade cases, 46.0 min (IQR, 27.0-79.0 min) for proposed
ADR cases, and 14.0 min (IQR, 13.5-41.5 min) (P=.12) for
proposed retrograde cases; median times for any wire/strategy
successful crossing were 69.5 min (IQR, 47.0-110.2 min) for
proposed antegrade cases, 34.0 min (IQR, 32.0-39.5 min) for
proposed ADR cases, and 108.0 min (IQR, 80.0-110.0 min)
(P<.01) for proposed retrograde cases.
Procedural complications. Table 6 summarizes
in-hospital complications. Overall MACE rates were low, at
1.3%. There were 7 total perforations, two of which were
wire perforations of the CTO vessels with non-XTRA
wires.There were no perforations directly related to use of
XTRA wire.There were no in-hospital deaths.
Discussion
In the present study, we report our initial clinical experi-
ence with novel (to the United States), dual-coil, compos-
ite-core guidewires (Fielder XT-R and Fielder XT-A) with
design characteristics optimized for AWE-CTO crossing.The
major findings of our paper are: (1) the Fielder XTRA wires
are able to achieve high rates of antegrade success in low-com-
plexity lesions; (2) when able to cross antegrade, the Fielder
XTRA wires maintain low wiring times despite lesion com-
plexity; (3) the Fielder XTRA wires do not perform as well
in traditionally challenging antegrade subsets including mod-
erate/severe calcification, moderate/severe tortuosity, lesions
≥20 mm, non-tapered stumps, ambiguous caps, and bypassed
vessels; and (4) the Fielder XTRA wires have low complica-
tion rates when used as part of an antegrade approach.
Our results show that both the J-CTO score and hybrid
algorithm are good predictors of procedural success when
attempting to wire a CTO antegrade using the XTRA
wires. XTRA wires showed good performance up to a
J-CTO score of 3, achieving 79% and 60% success rates for
J-CTO scores of 0-1 and 2-3, respectively, without the need
for an additional wire. At higher J-CTO scores (4-5), the
XTRA wires have limited ability to cross on their own (17%
success rate), although they may facilitate the AWE approach
with the addition of higher-force wires as needed (37%
overall antegrade success when starting with XTRA).When
the hybrid algorithm recommended starting antegrade, the
XTRA crossed on its own 74% of the time, but this num-
ber decreased to 44% when ADR was recommended and
24% when retrograde was recommended. Hence, the initial
limitations of antegrade wiring that led to the development
of the hybrid algorithm, as a general trend, also apply to the
XTRA wires. Comparing the performance of the XTRA
wires with other reports is difficult, as most studies do not
break down the specific wire that crossed the lesion. For
Table 5. Wiring times by proposed hybrid algorithm strategy.
Wiring Times by Strategy Proposed Hybrid Algorithm Strategy
Antegrade ADR Retrograde P-Value*
XTRA antegrade crossing (minutes) 8.0 (4.5-13.5) 9.0 (5.0-11.0) 15.0 (14.8-16.0) .10
Any wire antegrade crossing (minutes) 22.0 (17.5-31.0) 46.0 (27.0-79.0) 14.0 (13.5-41.5) .12
Any strategy crossing (minutes) 69.5 (47.0-110.2) 34.0 (32.0-39.5) 108.0 (80.0-110.0) <.01
Data presented as median (interquartile range). *
Kruskal-Wallis test. ADR = antegrade dissection and re-entry.
Table 6. Adverse events.
(n = 164)
In-hospital major adverse cardiovascular
event
2 (1.3%)
Death 0 (0.0%)
Perforation 7 (4.4%)
Location of perforation
CTO vessel 3 (1.9%)
Septal collateral 2 (1.2%)
Epicardial collateral 2 (1.2%)
Mechanism of perforation
Wire 4 (2.4%)
Microcatheter 2 (1.2%)
Stent 1 (0.6%)
Ellis class
1 3 (1.9%)
2 2 (1.2%)
3 2 (1.2%)
Treatment of perforation
None 4 (2.4%)
Coil 1 (0.6%)
Covered stent 1 (0.6%)
Fat 1 (0.6%)
Small hematoma 8 (5.2%)
Large hematoma 2 (1.2%)
Other complications 4 (2.4%)
Data presented as number (%).
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166 The Journal of Invasive Cardiology®
example, in the RECHARGE registry, 94% of cases with a
J-CTO score ≤1 were started with an AWE approach, with
86% achieving antegrade success. In RECHARGE lesions
with a J-CTO score ≥2, 74% were started with AWE and
50% achieved success. Overall, our results appear similar, al-
though it is not clear how many of the cases in the RE-
CHARGE registry required the use of a high-force, stiff
wire.When RECHARGE was broken down by hybrid al-
gorithm strategy, 77% of cases were started antegrade with
only 62% achieving antegrade success.8
Our results compare
very favorably with these findings regardless of the inclusion
of the other wires used in RECHARGE, as we were able
to achieve antegrade success with the XTRA alone in 74%
of cases recommended for AWE by the hybrid algorithm.
Our results also compare favorably with a recent report from
the PROGRESS registry that showed AWE success rates of
50.6% and 31.9% in lesions with J-CTO score 2-3 vs our
success rates of 60% with XTRA alone for J-CTO score
2-3 and overall antegrade success rate of 77% with use of
any wire. Furthermore, in PROGRESS, only 53.4% of cases
recommended for AWE by the hybrid algorithm ultimately
achieved antegrade success.9
Our results are also supported
by those presented by Galassi et al,10
who compared success
rates by J-CTO score in two different eras (2005-2009 vs
2010-2014). In this study,10
during the 2005-2009 era, a soft
(<1 g) wire was used to successfully cross the CTO lesion in
51.6%, 39.6%, 32.8%, and 32.3% for J-CTO scores of 0, 1, 2,
and ≥3, respectively, as compared with 94.4%, 86%, 76%, and
61.5%, respectively, for the same J-CTO scores in the 2010-
2014 era. As XTRA became available in Europe in 2010,
these results may at least partially reflect the impact of these
wires, although specifics regarding wire use and crossing
strategy were not reported.10
Our study is the first to spe-
cifically comment on the performance of the XTRA wires.
Selective subgroup analysis showed the XTRA wires were
less successful in calcified lesions, tortuous lesions, lesions
≥20 mm, non-tapered stumps, ambiguous caps, and bypassed
vessels.There was a trend toward lower success rates in left
FIGURE 1. Antegrade success rates stratified by J-CTO score. All
cases were started antegrade using Fielder XT-R/XT-A (XTRA)
wires. Cases in which an additional wire was needed to cross
antegrade are denoted by the “any wire antegrade success”
column; cases in which an additional strategy was required are
denoted by the “any wire/strategy success” column. Differenc-
es in success rates across J-CTO strata were significant for all
categories. J-CTO = Japanese Chronic Total Occlusion score.
FIGURE 3. Subgroup analysis of XTRA antegrade success
rates. Subgroup analysis of percent success rates for ante-
grade crossing with Fielder XT-R/XT-A (XTRA) wires. Groups
were chosen a priori based on perceived clinical relevance.
P-values indicate comparisons of groups within brackets. LAD
= left anterior descending coronary artery; LCX = left circum-
flex coronary artery; RCA = right coronary artery.
FIGURE 2. Antegrade success rates stratified by proposed hy-
brid algorithm strategy. All cases were started antegrade using
Fielder XT-R/XT-A (XTRA) wires. Cases in which an additional
wire was needed to cross antegrade are denoted by the “any
wire antegrade success” column; cases in which an additional
strategy was required are denoted by the “any wire/strategy
success” column. Differences in success rates across proposed
hybrid algorithm strata were significant for antegrade XTRA
success and any wire antegrade success (P<.001), but not for
any wire/strategy success (P=.25).
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7. Vol. 32, No. 5, May 2020 167
Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
circumflex lesions that did not reach statistical significance.
These findings are similar to previously reported correlates
of success in CTO percutaneous coronary interventions. In
the PROGRESS registry, calcification, tortuosity, and prox-
imal cap ambiguity were also associated with lower success
rates using any CTO approach.9
A report by Suzuki et al11
analyzed the results of expert Japanese operators employing
a primary antegrade approach and found severe calcification
and tortuosity of the CTO lesion to be the only multivar-
iate predictors of failure. Alessandrino et al12
developed a
predictive score for CTO wiring success based on a data-
base of procedures performed at two centers in France from
2004-2013.Although any CTO crossing technique could be
used, only 9.3% employed a retrograde approach, implying
a preference toward antegrade wiring. Independent predic-
tors of failure in this study were lesion calcification, previous
coronary artery bypass grafting, length ≥20 mm, prior MI,
blunt stump, and non-left anterior descending coronary ar-
tery lesion.12
One of the most intriguing findings of our study is that
in lesions where the XTRA was able to cross antegrade,
wiring times were low and not significantly impacted by
J-CTO score or the recommended hybrid algorithm strat-
egy. In the original derivation of the J-CTO score by Mo-
rino et al,5
successful antegrade guidewire crossing within
30 min was achieved in 87.7%, 67.1%, 42.4%, and 10.0%
for J-CTO scores of 0, 1, 2, and ≥3, respectively.This com-
pares favorably with our median wiring times of 6.5 min,
9.0 min,and 12.0 min for J-CTO scores of 0-1,2-3,and 4-5,
respectively. These results are not directly comparable with
the study by Morino et al, as their results represented use
of any antegrade wire, including high-force, stiff wires that
were likely to be used in more complex cases, as opposed
to those able to be crossed in our study with the XTRA
wires. However, in our J-CTO 2-3 category, we achieved
60% success using XTRA with a median wiring time of 9
min,which does represent a direct improvement in outcome
when compared with the Morino study that showed wiring
time <30 min in only 42.4% of patients with J-CTO score
of 2 (J-CTO scores 3-5 were combined, so comparison with
a score of 3 is not possible). In addition, even when allowing
any antegrade wire, we were able to achieve success in 77%
of patients with J-CTO score of 2-3 with a median wiring
time of 29 min, providing some support to the notion that
the XTRA may facilitate antegrade wiring with additional
wires. Notably, Morino’s study occurred prior to the devel-
opment of XTRA; hence, it is possible our improved wiring
times are at least partially due to this new technology. In ad-
dition,in a 2014 study by Michael et al,6
the mean time used
per crossing approach was 32 ± 23 min.While this number
represents any crossing strategy, it does provide some frame
of reference for the significance of our results.
Lastly, use of XTRA wires was associated with low com-
plication rates.We report only 4 wire perforations, none of
which were related to use of XTRA wires and only 2 of
which were wire perforations of the CTO vessel (the other 2
wire perforations occurred during collateral crossing).These
results compare favorably with historical cohorts. In a 2010
report by expert Japanese operators,13
there was a 0.2% rate
of perforation/contrast staining in the CTO artery.The 2018
FIGURE 4. Wiring times in successful cases stratified by J-CTO
score. Time from first wire insertion to wire crossing in min-
utes in all successful cases. Cases crossed with a Fielder XT-R/
XT-A (XTRA) wire are denoted by the “XTRA antegrade cross-
ing” column; cases in which an additional wire was needed
to cross antegrade are denoted by the “any wire antegrade
crossing” column; cases in which an additional strategy was
required are denoted by the “any strategy success” column.
J-CTO = Japanese Chronic Total Occlusion score.
FIGURE 5. Wiring times in successful cases stratified by pro-
posed hybrid algorithm strategy score. Time from first wire
insertion to wire crossing in minutes in all successful cases.
Cases crossed with the Fielder XT-R/XT-A (XTRA) wire are
denoted by the “XTRA antegrade crossing” column; cases in
which an additional wire was needed to cross antegrade are
denoted by the “any wire antegrade crossing” column; cases
in which an additional strategy was required are denoted by
the “any strategy success” column.
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8. Fielder XTRA Wires for Antegrade CTO-PCI ROSSI, et al.
168 The Journal of Invasive Cardiology®
update of the PROGRESS registry reported a 1.16% perfo-
ration rate in antegrade procedures.9
Notably, rates of per-
foration in this report were 5.22% with the ADR approach
and 7.52% with a retrograde approach, further supporting
the potential safety advantage of enhancing the success of
antegrade wiring.
Study limitations. Our study is limited by the lack of
a direct comparison with other potential starting wires per-
formed during the same time period. Furthermore, our re-
sults represent the experience of a single institution during a
particular time period.Whether or not these results are ap-
plicable to all CTO operators, each with their own skill set,
cannot be determined by this report. Lastly, we do not have
information on how or why an operator chose to persist
with the XTRA wire or move to a different wire, making
the mechanism of antegrade wire failure unclear.
Conclusion
We provide our initial experience with the Fielder XT-R
and XT-A wires in a contemporary population of unselect-
ed CTO patients treated at a single center. We believe our
results show excellent performance for the XTRA wires in
both procedural success and wiring times, with relative im-
provements as compared with historical reports throughout
the spectrum of lesion complexity.We suggest operators con-
sider starting with these wires as part of an initial antegrade
wiring approach and speculate that technological advance-
ments such as the XTRA wires may change the spectrum of
lesion recommended for an antegrade-first approach.
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From the Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland,
Ohio.
Disclosure: The authors have completed and returned the ICMJE Form for
Disclosure of Potential Conflicts of Interest. Dr Khatri reports an institutional
research grant from Asahi Intecc and honoraria/consulting fees from Abbott
Vascular and Boston Scientific. Dr Ellis reports consultant income from Abbott
Vascular, Boston Scientific, and Medtronic. The remaining authors report no
conflicts of interest regarding the content herein.
Manuscript submitted December 18, 2019 and accepted given December 26,
2019.
Address for correspondence: Dr Jeffrey Rossi, Cleveland Clinic, 9500 Euclid Ave-
nue, J2-3, Cleveland, OH 44195. Email: rossij4@ccf.org
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