Predictors for Successful Endovascular Intervention in Chronic Carotid Artery Total Occlusion

JACC: CARDIOVASCULAR INTERVENTIONS

VOL. 9, NO. 17, 2016

ª 2016 BY THE AMERICAN COLLEGE OF CARDIOLOGY FOUNDATION

ISSN 1936-8798/$36.00

PUBLISHED BY ELSEVIER

http://dx.doi.org/10.1016/j.jcin.2016.06.015

PERIPHERAL

Predictors for Successful Endovascular Intervention in Chronic Carotid Artery Total Occlusion Ying-Hsien Chen, MD,a Weng-San Leong, MD,b Mao-Shin Lin, MD,a,c Ching-Chang Huang, MD,a Chi-Sheng Hung, MD,a Hung-Yuan Li, MD,a Kok-Kheng Chan, MD,d Chih-Fan Yeh, MD,a Ming-Jang Chiu, MD, PHD,e Hsien-Li Kao, MDa

ABSTRACT OBJECTIVES This study sought to determine predictors for successful endovascular treatment in patients with chronic carotid artery occlusion (CAO). BACKGROUND Endovascular recanalization in patients with chronic CAO has been reported to be feasible, but technically challenging. METHODS Endovascular attempts in 138 consecutive chronic CAO patients with impaired ipsilateral hemisphere perfusion were reviewed. We analyzed potential variables including epidemiology, symptomatology, angiographic morphology, and interventional techniques in relation to the technical success. RESULTS The technical success rate was 61.6%. Multivariate analysis showed absence of prior neurologic event (odds ratio [OR]: 0.27; 95% confidence interval [CI]: 0.10 to 0.76), nontapered stump (OR: 0.18; 95% CI: 0.05 to 0.67), distal internal carotid artery (ICA) reconstitution via contralateral injection (OR: 0.19; 95% CI: 0.05 to 0.75), and distal ICA reconstitution at communicating or ophthalmic segments (OR:0.12; 95% CI: 0.04 to 0.36) to be independent factors associated with lower technical success. Point scores were assigned proportional to model coefficients, and technical success rates were >80% and <40% in patients with scores of #1 and $4, respectively. The c-indexes for this score system in predicting technical success was 0.820 (95% CI: 0.748 to 0.892; p < 0.001) with a sensitivity of 84.7% and a specificity of 67.9%. CONCLUSIONS Absence of prior neurologic event, nontapered stump, distal ICA reconstitution via contralateral injection, and distal ICA reconstitution at communicating or ophthalmic segments were identified as independent negative predictors for technical success in endovascular recanalization for CAO. (J Am Coll Cardiol Intv 2016;9:1825–32) © 2016 by the American College of Cardiology Foundation.

C

arotid artery occlusion (CAO) is associated

midterm results of endovascular treatment of chronic

with a 6% to 20% annual risk of recurrent

CAO have been reported (6,7), successful recanaliza-

ipsilateral ischemic stroke despite intensive

tion restores cerebral perfusion and may improve

medical treatment (1,2), and surgical bypass offers

neurocognitive function (8–10). However, CAO recan-

no benefit in preventing stroke (3–5). Feasibility and

alization is technically challenging and its potential

From the aDepartment of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan; bPantai Hospital Ipoh, Malaysia; c

Graduate Institute of Clinical Medicine, Medical College, National Taiwan University, Taipei, Taiwan; dKPJ Penang Specialist

Hospital, Penang, Malaysia; and the eDepartment of Neurology, National Taiwan University Hospital, Taipei, Taiwan. The authors have reported that they have no relationships relevant to the contents of this paper to disclose. Drs. Chen and Leong contributed equally to this work. Manuscript received February 22, 2016; revised manuscript received June 3, 2016, accepted June 5, 2016.

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Predictors for Successful CAO Recanalization

ABBREVIATIONS

complication may be life threatening. There-

INTERVENTIONAL

AND ACRONYMS

fore, the acceptance and dissemination of

were performed via an 8-F femoral sheath. Aspirin 100

this procedure has been slow. We present a

mg and clopidogrel 75 mg daily for at least 7 days were

retrospective analysis of CAO recanalization

given before the procedure. Heparin was given to

attempts to identify predictors for technical

maintain activated clotting time within 200 to 250 s.

success; a scoring system was constructed

The target common carotid artery (CCA) was engaged

ICA = internal carotid artery

to facilitate better case selection for begin-

with 8-F JR 4 guiding catheter. Intraluminal wiring

OA = ophthalmic artery

ning operators.

using coronary guidewires and microcatheters has

CAO = carotid artery occlusion CCA = common carotid artery CI = confidence interval

TECHNIQUES. All interventions

been described (6) as well as the alternative subintimal

OR = odds ratio

METHODS

tracking with antegrade re-entry technique (14). Wiring was abandoned after 30 minutes of futile effort,

PATIENTS. We conducted a retrospective analysis of

consumption of >300 ml of contrast, or when the wire

consecutive

tip is confirmed to be extravascular.

CAO

recanalization

attempts

from

October 2004 to April 2015 in National Taiwan Uni-

Once wire enters the distal true lumen, the micro-

versity Hospital and affiliated hospitals. CAO was

catheter was exchanged to a 1.5-mm diameter

detected by Doppler ultrasound, computed tomogra-

coronary balloon for pre-dilation. Distal embolic

phy, magnetic resonance imaging, or conventional

protection device would be deployed if an adequate

angiography. Brain computed tomography perfusion

landing zone can be identified. Properly sized balloon

with acetazolamide (Diamox) stress was performed

expandable stents (for segments in and above carotid

before carotid intervention to document ipsilateral

canal) and self-expanding stents (for cervical ICA)

hemisphere perfusion abnormality in all patients,

were then deployed to scaffold the occlusion. Balloon

with method as described previously (10). Prior

post-dilation may be done if stent expansion was not

neurologic symptoms were defined as ipsilateral

adequate. The intervention was considered a tech-

transient ischemic attack or ischemic stroke or

nical success if the occlusion segment was stented

amaurosis fugax. The duration from the last neuro-

with final residual diameter stenosis of #20%, and

logic event to intervention was recorded and cate-

establishing grade 3 antegrade TICI flow.

gorized as #6 months, >6 months, or no history of

READING OF ANGIOGRAMS. An independent inter-

neurologic event before the diagnosis of CAO. Endo-

ventionist reviewed the procedural angiograms off-

vascular recanalization attempts were made after

line, and morphologic characteristics regarding the

obtaining informed consent. Clinical and neurologic

stump, occlusion segment, and distal ICA reconstitu-

data, angiography findings, and interventional results

tion were recorded. A stump was present if there was

were

independent

contrast filling within the segment of cervical ICA after

neurologist and interventionist. The retrospective

it bifurcates from the CCA, proximal to the occluded

review of the clinical information and radiologic re-

segment. Stump angulation was measured using CCA

cords of the patients were approved by the Institu-

as the reference axis at lateral view, and categorized

tional Review Board at National Taiwan University

into >45
or #45
. It would be designated as >45
for

Hospital.

analysis if stump was absent. The occlusion site was

collected

and

reviewed

by

categorized as CCA, cervical ICA, or intracranial ICA.

SEE PAGE 1833

Distal carotid visibility was defined as the presence of

ANGIOGRAPHY. Selective cerebral angiography was

contrast reconstitution in the ICA distal to the occlu-

done via femoral approach before intervention.

sion, either during selective ipsilateral, contralateral,

Pseudo-occlusion

criteria

or vertebral injection. The most proximal level of distal

described in the literature (11,12). Angiographic criteria

carotid artery reconstitution was categorized as at

of true occlusion were: 1) discontinuation of lumen

petrous segment or below, cavernous segment, clinoid

>5 mm in length; 2) grade 0 Thrombolysis In Cerebral

segment, ophthalmic segment, and communicating

was

ruled

out

using

Infarction (TICI) antegrade flow distal to the occlusion;

segment. Reversed OA flow was defined as the pres-

and 3) established collateral filling to the ipsilateral

ence of contrast flow in OA with reversed flow direction

intracranial internal carotid artery (ICA) territory,

during ipsilateral injection. The occlusion length was

either via anterior communicating artery, posterior

measured from the occlusion site to the distal recon-

communicating artery, ipsilateral ophthalmic artery

stituted ICA in lateral projection, in straight line

(OA), or other brachiocephalic artery branches. Diam-

ignoring potential curvature of the occluded segment.

eter stenosis was calculated using the NASCET (North

The occlusion length was categorized as #50 or >50

American Symptomatic Carotid Endarterectomy Trial)

mm. If the distal ICA was not visible, the occlusion

method (13).

length would be designated as >50 mm.

Chen et al.

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STATISTICAL ANALYSIS. All continuous variables

were expressed as mean  SD, and categorical vari-

T A B L E 1 Patient Characteristics

Failure (n ¼ 53)

ables in numbers and percentage. The chi-square test or Fisher’s exact test (if the group’s number is 5 or

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Predictors for Successful CAO Recanalization

Success (n ¼ 85)

Total (n ¼ 138)

p Value

Age, yrs

66.0  10.5

67.1  9.5

66.7  9.8

0.73

Male, %

77.4

87.1

83.3

0.14

Hypertension, %

79.2

81.2

80.4

0.78

significant. Stata/SE 11.0 for Windows (StataCorp LP,

Diabetes mellitus, %

20.8

32.9

28.3

0.12

Texas) was used for statistical analyses. Sensitivity

Hyperlipidemia, %

37.7

55.3

48.6

0.045

and specificity were measured by the Youden index.

Smoking, %

37.7

31.8

34.1

0.47

less) was used to compare groups of categorical data. A 2-sided p value of 0.05 was considered statistically

RESULTS A total of 138 consecutive CAO recanalization attempts were performed in 138 patients (115 men; age

Under dialysis, %

1.9

1.3

1.5

0.79

Neck radiation, %

11.3

8.0

9.4

0.53

Any neurologic event #6 months, %

35.8

55.3

47.8

0.03

Any neurologic event >6 months, %

9.4

8.2

8.7

0.81

54.8

36.5

43.5

0.04

45.3

62.4

55.8

0.05

Duration from last neurologic event*

No neurologic event, %

66.7  9.7 years; range: 41 to 86 years) with overall

Significant CAD, %

technical success rate 61.6%. Tables 1 and 2 summa-

Total cholesterol, mg/dl

174  34

172  44

173  40

0.36

rized the demographics and lesion characteristics.

Creatinine, mg/dl

1.37  1.45

1.17  0.48

1.25  1.0

0.13

Among 138 ICA occlusion patients, 43.5% of the pa-

eGFR, ml/min

71.2  29.6

70.9  21.4

71.0  25.0

0.48

tients did not have history of neurologic events and 47.8% received recanalization attempts within 6 months from the last neurologic events. During ce-

Values are  SD or %. *Neurologic event was defined as transient ischemic attack, ischemic stroke or amaurosis fugax; CAD ¼ coronary artery disease; eGFR ¼ estimated glomerular filtration rate, was calculated by the Modification of Diet in Renal Disease (MDRD) formula.

rebral angiography, calcification was present in 37.0% of the occlusions, and tapered stump (76.1%) with a stump angle of >45
(18.8%) was seen in the majority. An occlusion length of >50 mm was seen in 86.2%.

95% CI: 1.03 to 4.28), and duration from last neurologic event #6 months (OR: 2.2; 95% CI: 1.09 to 4.48). Multivariate analysis using stepwise backward

Distal carotid artery can be visualized by contralateral

and forward method was then performed (Table 4).

CCA injection in 23.2%, and 63.8% with reversed

No history of neurologic event (OR: 0.27; 95% CI: 0.10

OA flow.

to 0.76), nontapered stump (OR: 0.18; 95% CI: 0.05

Hyperpefusion syndrome with delayed nonfatal intracranial hemorrhage developed in 2 patients after successful recanalization. Another 2 patients suffered

T A B L E 2 Lesion Characteristics

from subarachnoid hemorrhage and intracranial hemorrhage related to wire extravasation; 1 died after cra-

Failure (n ¼ 53)

Success (n ¼ 85)

Total (n ¼ 138)

p Value

niectomy. Another mortality occurred in a patient with

Left lesion, %

58.5

52.9

55.1

0.52

history of neck radiation for nasopharyngeal cancer,

Calcification over occluded segment

30.2

41.2

37.0

0.19

due to delayed massive paranasal sinus bleeding

Stump condition

possibly related to wire trauma. There is 1 subacute

Tapered, %

67.9

81.2

76.1

0.08

stent thrombosis with stroke. Therefore, 30-day pro-

Blunt, %

28.3

12.9

18.8

cedural complication rate including stroke, intracranial hemorrhage, and death was 4.3% (6 of 138), and overall 30-day mortality was 1.4% (2 of 138). Univariate analysis was performed with logistic regression after adjusting age and sex to determine predictors for technical success (Table 3). Success rate was lower in occlusions without prior neurologic event (OR: 0.45; 95% CI: 0.22 to 0.96), nontapered stump (OR: 0.33; 95% CI: 0.13 to 0.82), occlusion site

3.8

5.9

5.1

Stump angle >45
, %

No stump, %

26.4

14.1

18.8

Occlusion length >50 mm

90.6

83.5

86.2

Occlusion site CCA Cervical ICA Intracranial ICA Reversed ophthalmic artery flow

1.9

10.6

7.2

88.7

88.2

88.5

9.4

1.2

4.3

56.6

68.2

63.8

Petrous segment or below

3.8

30.5

20.3

Cavernous segment

9.4

23.5

18.1

15.1

25.9

21.7

distal ICA reconstitution via contralateral injection

Ophthalmic segment

34.0

10.6

19.6

Communicating segment

37.8

9.4

20.3

41.5

11.8

23.2

Distal ICA reconstitution with contralateral injection

CI: 0.01 to 0.20) and at communicating segment (OR: 0.03; 95% CI: 0.01 to 0.17). The technical success rate was greater in patients with hyperlipidemia (OR: 2.10;

Values are %. CCA ¼ common carotid artery; ICA ¼ internal carotid artery.

0.17 <0.001

Level of distal ICA reconstitution

Clinoid segment

reconstitution at ophthalmic segment (OR: 0.04; 95%

0.24 0.01

at intracranial ICA (OR: 0.02; 95% CI: 0.001 to 0.50), (OR: 0.19; 95% CI: 0.08 to 0.44), with the level of

0.07

<0.001

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Predictors for Successful CAO Recanalization

system can be created to predict success rate of CAO

T A B L E 3 Logistic Regression of Predictors of Technical Success

recanalization. Points were assigned to each variable

Odds Ratio (95% CI)

p Value

proportional to its regression coefficients rounded to

Hypertension

1.00 (0.45–2.64)

0.85

the nearest integer. Table 5 summarized the actual

Diabetes mellitus

1.86 (0.83–4.18)

0.13

score points assigned, and the success rates of

Hyperlipidemia

2.10 (1.03–4.28)

0.04

Smoking

0.61 (0.28–1.32)

0.21

different total score points. For lesions with score of #1, the technical success rate was >80%. If the score

Neck radiation therapy

0.67 (0.20–2.28)

0.53

Significant coronary artery disease

1.80 (0.87–3.74)

0.12

was $3, then the success rate decreased significantly

Duration from last neurologic event #6 mo

2.20 (1.09–4.48)

0.03

to <40%. The c-index on the basis of area under the

Duration from last neurologic event >6 mo

0.60 (0.17–2.14)

0.43

curve for this scoring system in predicting technical

No neurologic event

0.45 (0.22–0.96)

0.04

success was 0.820 (95% CI: 0.748 to 0.892; p < 0.001),

Nontapered stump

0.33 (0.13–0.82)

0.01

Calcification over occluded segment

1.60 (0.75–3.44)

0.22

Stump angulation >45


0.54 (0.23–1.25)

0.15

Occlusion length >50 mm

0.53 (0.17–1.59)

0.26

Occlusion site

with a sensitivity of 84.7% and a specificity of 67.9% (Figure 1). EXAMPLE CASE 1. A 67-year-old man presented with

transient left upper limb weakness 4 months before –

–

0.15 (0.02–1.24)

0.08

0.02 (0.001–0.50)

0.02

CCA Cervical ICA Intracranial ICA Reversed ophthalmic artery flow

1.54 (0.75–3.17)

0.24

Distal ICA reconstitution with contralateral injection

0.19 (0.08–0.44)

<0.001

CAO recanalization (score point 0). Angiography showed right ICA

occlusion

with blunt stump

morphology (2 points) (Figure 2A). Distal carotid artery was visible via contralateral contrast injection (2 points), with level of distal ICA reconstitution at

Level of distal carotid artery reconstitution –

–

Cavernous segment

0.31 (0.05–1.76)

0.19

Clinoid segment

0.21 (0.04–1.10)

0.07

Ophthalmic segment

0.04 (0.01–0.20)

<0.001

Communicating segment

0.03 (0.01–0.17)

<0.001

Petrous segment or below

communicating segment (2 points) (Figure 2B). The total CAO score for this lesion was 6, and thus the success rate of recanalization would be estimated low (20%). EXAMPLE CASE 2. A 51-year-old man presented with

left limbs weakness 2 years before CAO recanalization

CI ¼ confidence interval; other abbreviations as in Table 2.

(0 point). Angiography showed right ICA occlusion with tapered stump morphology (0 point) (Figure 2C). to 0.67), distal ICA reconstitution with contralateral injection (OR: 0.19; 95% CI: 0.05 to 0.75), or level of distal carotid artery reconstitution at communicating or ophthalmic segments (OR: 0.12; 95% CI: 0.04 to 0.36) were identified as independent negative predictors for technical success in CAO recanalization.

Distal carotid artery was visible with ipsilateral contrast injection (0 point) with level of distal ICA reconstitution

dictors obtained from multivariate analysis, a scoring

T A B L E 4 Multivariate Analysis of Predictors of Technical Success Using

Multiple Backward Stepwise Selection with Age and Sex Adjusted

segment

(0

point)

and thus the success rate of recanalization would be

DISCUSSION Chronic CAO is associated with annual stroke rates of 6% to 20%, despite intensive medical treatment (1,2). Although

Odds Ratio (95% CI)

cavernous

high (>90%).

CAO SCORING SYSTEM. Using the independent pre-

Coefficient

at

(Figure 2D). The total CAO score for this lesion was 0,

p Value

Male

0.08

0.93 (0.23–3.66)

0.892

Age, yrs

0.01

0.99 (0.95–1.04)

0.599

several

nonrandomized

extracranial-

intracranial bypass studies have shown positive results (15–17), both the milestone EC-IC Bypass trial and Carotid Occlusion Surgery Study (3–5) failed to

Hypertension

1.30

0.27 (1.02–13.2)

0.05

Hyperlipidemia

0.93

2.54 (0.97–6.66)

0.06

demonstrate any difference in fatal and nonfatal

No neurologic event

1.31

0.27 (0.10–0.76)

0.01

strokes at 2 to 5 years between surgical and medical

Nontapered stump

1.69

0.18 (0.05–0.67)

0.01

groups in symptomatic CAO patients. The high peri-

Distal ICA reconstitution with contralateral injection

1.66

0.19 (0.05–0.75)

0.02

procedural complications seen in the surgical group is

Occlusion site at CCA Level of distal carotid artery reconstitution at communicating or ophthalmic segments Abbreviationsas in Tables 2 and 3.

2.2 2.16

8.6 (0.67–110.40) 0.12 (0.04–0.36)

0.10 <0.001

mainly due to the intolerance of procedural hemodynamic fluctuation (18). Endovascular recanalization of CAO, in contrast, may offer the same reperfusion advantage with less procedural hemodynamic compromise. Successful recanalization of chronic CAO patients may

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T A B L E 5 CAO Score of Carotid CTO Intervention

Neurologic event

F I G U R E 1 ROC Curves of CAO Score in Predicting Technical Success

Status

Coefficient

Score Point

History of neurologic event

-1.31

0

-1.69

0

No neurologic event Stump morphology

Tapered stump

1

Blunt stump or no stump Distal carotid artery reconstitution

2

Via ipsilateral injection

-1.66

0

Via contralateral injection Level of distal carotid artery reconstitution

2

At or before clinoid segment

-2.16

0

At communicating or ophthalmic segments Total CAO Score Points

2

Success Rate (%)

0

92

1

80

2

65

3,4

31

$5

20

The c-indexes on the basis of AUCs for CAO score in predicting technical success was 0.820 (95% CI: 0.748 to 0.892; p < 0.001). AUC ¼ area under the curve; CAO ¼ carotid artery occlusion; ROC ¼ receiver operating characteristic.

CAO ¼ carotid artery occlusion; CTO ¼ chronic total occlusion.

improve global cognitive function, as well as atten-

procedure was attempted. The resulting firm, calci-

tion and psychomotor processing speed, compared

fied, and long occlusion segment is therefore more

with medical treatment (8,10,19). Unfortunately,

resistant to endovascular intervention. This is clearly

endovascular recanalization of CAO is technically

shown in our analysis.

challenging, because the occlusion length is usually

A tapered stump at the occlusion facilitates wire

long with wide individual variation of the occluded

entry into the occluded segment, whereas a blunt

vessel segment course. Visual clues for wiring

stump or absence of stump increases the difficulty.

across the occlusion, such as bridging collateral or

This is well-demonstrated in our study. Because the

distal

lacking.

majority of CAO start at the proximal cervical ICA just

Furthermore, potential complications after wiring

distal to the CCA bifurcation, less angulation between

injury, including hemorrhage, pseudoaneurysm, and

the CCA and ICA axes may also enhance forward force

carotid-cavernous fistula (20,21), may be catastrophic

delivery and wire entry. However, stump angulation

artery

reconstitution,

are

often

and deterred inexperienced operators from embark-

was shown to be insignificant in predicting technical

ing on the procedure. A systematic pre-procedural

success in our study.

evaluation is therefore important to identify patient

Occlusion length was known to affect success rate

and lesion characteristics that carry higher success

in endovascular recanalization for chronic total cor-

rates, and thus are helpful for the dissemination of

onary artery occlusion (23). In theory, longer occlu-

this procedure.

sion in CAO should also predict lower technical

It is intuitively reasonable that the duration from

success. Wiring across a long CAO is difficult due to

last event may affect technical success rate. As an

the variable vessel course, easily results in false

acute occlusion “ages,” its consistency may become

lumen creation and a higher chance of vessel injury.

hard and calcified, and its length will increase pro-

Arbitrarily, we categorize occlusion length by the

gressively with a thrombotic process. Both of these

cutoff of 50 mm, and the technical success rates in

mechanisms have been observed in coronary artery

short and long occlusions are 73.7% and 59.7%,

occlusions (22), increasing the difficulty of endovas-

respectively. The occlusion length was found insig-

cular recanalization. When CAO develops insidiously

nificant in predicting technical success (OR: 0.53; 95%

without a clear neurologic event, such “clinically

CI: 0.17 to 1.59), but only 19 CAO (13.8%) in the current

silent” occlusions may have actually progressed over

series were shorter than 50 mm. A larger case number

years

would be necessary to clarify whether an inverse

and

decades

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Predictors for Successful CAO Recanalization

before

the

recanalization

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Predictors for Successful CAO Recanalization

F I G U R E 2 Angiography of CA in Example Cases

(A) Example case 1 lateral view of right internal carotid artery (ICA) stump (arrow) in blunt morphology. (B) Example case 1 with visible right distal carotid artery (arrow) via contralateral injection. (C) Example case 2 lateral view of right ICA stump (arrow). (D) Example case 2 distal carotid artery can be seen with ipsilateral contrast injection (arrow).

relationship do exist between the occlusion length

major side branches should be preserved to maintain

and success rate of CAO recanalization.

long-term patency, subintimal tracking with anteoccluded

grade re-entry technique may be used more liberally

segment may hinder guide wire crossing, it has been

in CAO intervention because there is no major side

established as a negative predictor for success in

branch proximal to OA.

Because

severe

calcification

in

the

coronary intervention for chronic occlusions (23).

Visualization of the distal ICA by ipsilateral

Interestingly, the success rate in occlusions with

contrast injection not only provides clear reference

calcification in our analysis was in fact higher (calci-

for wiring procedure, but because the most frequent

fied 68.6% vs. noncalcified 57.5%), although not sta-

ipsilateral collateral route is the reversed OA flow, it

tistically significant (OR: 1.60; 95% CI: 0.75 to 3.44).

also implies lumen patency from the OA takeoff to the

The potential reason is that calcification may actually

terminal ICA bifurcation. When the distal ICA is

provide a roadmap, and thus facilitate wiring pro-

reconstituted at levels distal to the ophthalmic

cedures in the highly variable cervical ICA anatomy.

segment, the difficulty of guide wire manipulation

In addition, most of the dense calcium burden in the

increases significantly. The operator has to negotiate

current series was located at the proximal occlusion

the wire through tortuous petrous/cavernous/clinoid

site, but not throughout the entire length of CAO.

segments of the occluded ICA, and also achieve wire

Once the proximal cap was penetrated with the de-

re-entry into true lumen in an intradural position.

vices described, the rest of the occlusion segment

The potential consequences of vessel injury or

with loose calcification may be then easily traversed

perforation are prohibitive for aggressive wire choice

using the subintimal tracking with antegrade re-entry

or manipulation. In fact, the success rates when distal

technique. Unlike in coronary interventions where

ICA reconstitution at segments of petrous or below,

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Predictors for Successful CAO Recanalization

cavernous, clinoid, ophthalmic, and communicating

and distal ICA reconstitution at communicating or

or above, were 93%, 80%, 73%, 33%, and 29%,

ophthalmic segments were identified as independent

respectively, rendering the level of distal ICA recon-

negative predictors for technical success in endovas-

stitution at ophthalmic or communicating segments

cular treatment for CAO.

predictive for a significantly lower rate of success (OR: 0.12; 95% CI: 0.04 to 0.36). The construction of a scoring system based on our data can be used as a predictive tool to estimate the technical success rate of endovascular recanalization for individual chronic CAO. It will be especially important and useful for beginners of the procedure, so that cases with less likelihood of success may be avoided. In addition, it also provides a basis for the comparison of complexity and difficulty of CAO cases

ACKNOWLEDGMENTS The

authors

acknowledge

statistical assistance provided by the Taiwan Clinical Trial Statistical Center, Training Center, and Pharmacogenomics Laboratory (which is founded by National Research Program for Biopharmaceuticals [NRPB] at the Ministry of Science and Technology of Taiwan; MOST 104-2325-B-002-032) and the Department of Medical Research in National Taiwan University Hospital.

in studies or discussions. This CAO scoring system should and will be used prospectively in future

REPRINT REQUESTS AND CORRESPONDENCE: Dr.

studies to validate its predictive power.

Hsien-Li Kao, Department of Internal Medicine,

STUDY LIMITATIONS. The case number of the pre-

sent study is relatively small, and this may obscure relevant factors and undermine the predictive power

National Taiwan University Hospital, 7 Chung-Shan South

Road,

100

Taipei,

Taiwan.

E-mail:

[email protected].

of the scoring system. More prospective patients are needed to validate current findings in the future. The present analysis only looked at factors associated

PERSPECTIVES

with technical success, without mention of complication and long-term clinical outcome. Although

WHAT IS KNOWN? Endovascular recanalization of chronic

these CAO patients with objective perfusion abnor-

carotid artery occlusion is technically challenging.

mality may enjoy improved neurocognitive function after successful recanalization (8,10,19), this potential benefit should be proven to outweigh the risk of procedural complication in further investigations.

CONCLUSIONS

WHAT IS NEW? We identified predictors for procedural success and constructed a scoring system based on patient/lesion characteristics. This would help interventionists in their initial learning curves to gauge and select appropriate cases. WHAT IS NEXT? Further validation of the scoring system in a

No history of neurologic event, nontapered stump,

larger prospective cohort is mandatory in the future.

distal ICA reconstitution by contralateral injection,

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KEY WORDS carotid artery, chronic total occlusion, endovascular stenting, predictors, scoring system