Keywords
posterior circulation stroke - mechanical thrombectomy - acute stroke
Introduction
Acute posterior circulation stroke is found in approximately 1% of patients with ischemic
stroke and contributes to a high mortality rate (85–95%) if untreated.[1] The previous studies demonstrated that treatment with intravenous recombinant tissue
plasminogen activator (rt-PA) administration and mechanical thrombectomy (MT) is still
limited due to incidents and unfavorable outcomes of treatment.[2]
[3] The Endovascular Stroke Treatment (ENDOSTROKE) registry revealed that functional
outcomes after endovascular treatment which is widely applied in German and Austrian
stroke centers contributed to poor safety, technical success, and clinical efficacy.[4]
In our hospital guideline for MT was established in 2015. The patient selection for
MT has been protocoled by using computed tomography angiography (CTA) or CT perfusion
for anterior circulation and magnetic resonance imaging (MRI) core infarction for
posterior circulation. According to guidelines of the early management of patients
with acute ischemic stroke, patients with posterior circulation stroke are advisable
to receive MT if they are indicated in class IIb based on Class of Recommendations
and Class C on Level of Evidence (LOE).[5]
Good or poor outcomes after MT procedure in patients with posterior circulation strokes
are associated with several factors, such as age, gender, and pre-stroke modified
Rankin Scale (mRS) of patients including intravenous thrombolysis administration,
initial National Institutes of Health Stroke Scale (NIHSS), comorbidity diseases,
smoking or alcohol consumptions, imaging data, mode of anesthesia, devices, number
of attempts, occlusion location, onset to groin puncture time, and recanalization
time.[6]
[7]
[8]
[9]
[10]
[11] The purpose of this study is to evaluate primary clinical outcomes of patients with
acute posterior circulation stroke who underwent MT treatment and to assess factors
associated with the good outcome of treatment.
Materials and Method
Study Design
The institutional ethics review board committee approved this retrospective analysis
to use patient charts, imaging data, and waived informed consent on this basis of
the study design (SIRB protocol No. IRB4–948/2563 [2019]).
Inclusion and Exclusion Criteria
A total of 549 medical records of patients with acute ischemic stroke who underwent
cerebral angiogram from January 2010 to December 2020 were investigated. The inclusion
criteria consisted of clinical signs, imaging data, angiographic findings, and outcome
data from patients diagnosed with acute stroke with or without undergoing MT and followed
up at 90 days. The exclusion criteria were those with incomplete clinical and/or imaging
data and without large vessel occlusion (LVO) from the cerebral angiogram. As a result,
80 patients with acute anterior circulation ischemic stroke and 6 patients with acute
posterior circulation ischemic stroke were excluded because LVO did not exist in the
cerebral angiogram and MT was not performed. Finally, 463 medical records were retrospectively
investigated. They were composed of 397 patients with acute anterior circulation ischemic
stroke and 66 patients with acute posterior circulation ischemic stroke treated with
MT.
Mechanical Thrombectomy for Posterior Circulation Stroke Guideline in our Hospital
According to our guideline for MT in patients with acute posterior circulation stroke,
the criteria for patient selection were LVO of posterior circulation (vertebrobasilar
system) without clinical signs or images of extensive brainstem infarction within
24 hours of symptom onset, NIHSS of 6 or greater, age of 18 years or less, and prestroke
mRS less than 2.
All patients were initially investigated with a noncontrast CT scan to exclude any
contraindication for MT, such as intracranial hemorrhage and large area of infarction.
The MRI brain stroke protocol emergency was always performed in suspected cases of
posterior circulation stroke in the same protocol for examining the presence or absence
of extensive brainstem infarction that defined as clinical that involved large area
of brainstem and cerebellar such as comatose condition, contralateral hemiparesis,
multiple cranial nerve involvement, cerebellar deficit, or ataxia. However, in the
case that MRI is not available because of coronavirus disease 2019 since 2020 or the
patient who had alteration of consciousness and not cooperated during MRI, either
single-phase CTA or multiphase CTA was accepted in the patients without clinical signs
of brainstem infarction according to the decision of the intervention neuroradiologist
consultant.
In our institute, the MT procedure was performed by four interventional neuroradiologists.
Based on an economic concern, aspiration technique was considered the primary procedure
in the selected case. The stent retrieval technique was a rescue treatment in cases
where the occlusion persisted after the attempt of aspiration technique. However,
the stent retrieval technique could be primarily performed in those with the site
of occlusion or occlusion pattern from reviews of noninvasive imaging at segment occlusion,
or dependent on the operator's justification.
General anesthesia was applied in selected cases to secure the airway during the procedure
especially in noncooperative patient and depended on the operator's preference. All
post-MT patients were closely observed at the stroke unit.
A noncontrast CT was routinely performed within the first 24 hours after MT to rule
out any kind of hemorrhage. Antiplatelet or anticoagulation therapy was then initiated.
The alternatives of therapy were dependent on neurologist's guideline based on the
suspected etiology of the stroke.
Post-MT follow-up was performed either at the outpatient department (OPD) or via telephone
for surveying the clinical signs either with patients or their caregivers. This approach
was routinely scheduled at 30 and 90 days post-MT for assessing the treatment outcomes.
Outcome Measurements
Case record forms were used to collect information on clinical signs, imaging data,
angiographic findings, and treatment outcomes. Follow-up data of the investigated
patients included gender, age, comorbidity (diabetes mellitus, hypertension, dyslipidemia,
atrial fibrillation, old cerebrovascular accident, coronary artery disease, cigarette
smoking), initial NIHSS, initial Glasgow Coma Scale (GCS), baseline mRS score, intravenous
alteplase administration, mode of anesthesia, MT procedure, rescue procedures, post-MT
NIHSS, stroke subtype according to the TOAST classification, clot pathology result,
postprocedural symptomatic intracranial hemorrhage (sICH) 24-hour, and length of hospital
stay.
Location of the clot was divided into the distal basilar artery (involvement of P1
or P2 segments of the posterior cerebral artery [PCA] to the distal origin of the
superior cerebellar arteries [SCAs]), the mid-basilar artery (involvement of the segment
between origins of the anterior inferior cerebellar arteries [AICAs] to the origins
of SCA), the proximal basilar artery (involvement of the vertebrobasilar junction
to the origins of the AICA), and the vertebral artery. The presence of posterior communicating
artery (PCoA) for this study included the presence of P1 segment of the PCA attaching
to the basilar artery apex and fetal origin PCA. The posterior circulation-Alberta
Stroke Program Early CT Score (pc-ASPECTS) was assessed by retrospective review of
the PCoA to visualize the PCoA artery of pre-MT CTA, magnetic resonance angiography,
and/or cerebral angiography.
Postprocedural sICH was defined as blood found at any site of the brain within 24 hours
after noncontrast CT scan. Stroke subtype was defined according to the TOAST classification.
Successful revascularization was recognized when score of modified thrombolysis in
cerebral infarction (mTICI) reached 2b or 3.
The clinical outcome was assessed with mRS at 90 days by clinical follow-up at OPD
or telephone interview with the patients or caregivers. A good outcome at 90 days
was considered when mRS was scored 0 to 2.
Statistical Analysis
All categorical data, including gender, comorbidity, smoking status, imaging modality
and evaluation, occlusion site, history of intravenous alteplase administration, general
anesthesia, primary procedural MT, first-pass success, rescue procedures, complete
reperfusion, postprocedural sICH, stroke subtype, clot pathology, post-24-hour NIHSS,
and dead, were collected and analyzed statistically with SPSS Statistics version 18.0.
Continuous variables consisted of age, initial NIHSS score, initial GCS, initial mRS,
initial systolic blood pressure (SBP), pc-ASPECTS, onset to puncture, onset to recanalization,
CT to puncture, puncture to recanalization, mTICI score, and length of stay. Variables
with normal distribution were reported with mean ± standard deviation, meanwhile those
with nonnormal distribution were demonstrated with median and range. Data between
good (mRS 0–2) and poor outcome (mRS 3–6) groups were assessed either by Fisher's
exact test for categorical variables or Mann–Whitney U test for continuous variables. Multivariate logistic regression analysis with binary
logistic regression method was performed to analyze the association between the prognosis
factor and good outcome. Statistical significance was defined when p-value less than 0.05.
Results
MT was performed in a total of 463 patients. Of those, 397 (86%) patients were diagnosed
with acute anterior circulation stroke; meanwhile, 66 (14%) patients were acute posterior
circulation stroke as demonstrated in [Fig. 1]. For acute anterior circulation stroke, the number of patients with a good outcome
(mRS 0–2) was 213 out of 397 (53.66%), whereas those with poor outcome (mRS 3–6) were
184 from 397 (46.34%). According to posterior circulation stroke, the patients with
a good outcome were 30 out of 66 (45.45%) where those with poor outcome were 36/66
(54.55%). The outcomes of MT between both groups were not statistically different
from each other (p = 0.21), as illustrated in [Fig. 2].
Fig. 1 Flowchart of patient selection and outcomes.
Fig. 2 Distribution of 90-day modified Rankin Scale (mRS) scores stratified by stroke location.
According to the demographic data, it was found that 39 (59.1%) men and 27 (40.9%)
women underwent posterior circulation stroke. The mean age at onset of stroke was
65.21 ± 12.72 years old, and the initial NIHSS mean was 18.5. Most common comorbidities
of patients were hypertension (92.4%), dyslipidemia (62.1%), atrial fibrillation (47%),
diabetes mellitus (45.5%), old cerebrovascular accident (25.8%), and coronary artery
disease (18.2%). Note that 33.3% of the patients were smokers and received intravenous
rt-PA administration during observation and general anesthesia was applied in most
cases (87.9%). Stent retriever MT (51.5%) technique was considered as a primary procedure,
on the other hand, contact aspiration MT (48.5%), which made first-pass success 40.9%
and need for rescue procedure was 59.1%.
Successful reperfusion (mTICI = 2b-3) was achieved in 61/66 (92.42%), which is 30/61
(49.18%) for good outcome and 31/61 (50.82%) for poor outcome; on the other hand,
unsuccessful reperfusion (mTICI = 0–2a) occurred in 5/66 (7.6%), which is 2/5 (40%)
for bedridden status and 3/5 (60%) for dead. Also, the rate of postprocedural sICH
was 5/66 (7.6%), mortality rate was 19/66 (31.18%), and length of hospital stay was
12.5 days ([Table 1]).
Table 1
Demographics as well as procedural and clinical outcomes of patients undergoing mechanical
thrombectomy after acute posterior circulation stroke
|
Variables
|
Over All
(n = 66)
|
Good outcome (n = 30)
|
Poor outcome (n = 36)
|
p-Value
|
|
Male, n (%)
|
39 (59.09)
|
17 (56.6)
|
22 (61.1)
|
0.714
|
|
Age (y), mean ± SD
|
65.21 ± 12.72
|
64.13 ± 13.04
|
66.11 ± 12.55
|
0.534
|
|
Initial NIHSS, mean (range)
|
18.5 (4–32)
|
14 (4–31)
|
21 (8–32)
|
0.001[a]
|
|
Comorbidity
|
|
Diabetes mellitus, n (%)
|
30 (45.50)
|
11 (36.7)
|
19 (52.8)
|
0.191
|
|
Hypertension, n (%)
|
61 (92.40)
|
26 (86.7)
|
35 (97.2)
|
0.169
|
|
Dyslipidemia, n (%)
|
41 (62.10)
|
17 (56.7)
|
24 (66.7)
|
0.404
|
|
Atrial fibrillation, n (%)
|
31 (47)
|
18 (60)
|
13 (36.1)
|
0.053
|
|
Old cerebrovascular accident, n (%)
|
17 (25.80)
|
8 (26.7)
|
9 (25)
|
0.877
|
|
Coronary artery disease, n (%)
|
12 (18.20)
|
4 (13.3)
|
8 (22.2)
|
0.351
|
|
History of smoking, n (%)
|
22 (33.33)
|
9 (30)
|
13 (36.1)
|
0.6
|
|
IV rt-PA administration, n (%)
|
22 (33.30)
|
14 (46.7)
|
8 (22.2)
|
0.036[a]
|
|
General anesthesia, n (%)
|
58 (87.9)
|
24 (80)
|
34 (94.4)
|
0.128
|
|
Contact aspiration MT, n (%)
|
32 (48.50)
|
17 (56.7)
|
15 (41.7)
|
0.471
|
|
Stent retriever MT, n (%)
|
34 (51.50)
|
13 (43.3)
|
21 (58.3)
|
0.471
|
|
First-pass success, n (%)
|
27 (40.90)
|
13 (43.3)
|
14 (38.9)
|
0.715
|
|
Rescue procedures, n (%)
|
39 (59.10)
|
17 (56.6)
|
22 (61.1)
|
0.715
|
|
Successful recanalization (mTICI = 2b–3), n (%)
|
61 (92.40)
|
30 (100)
|
31 (86.1)
|
0.145
|
|
Unsuccessful recanalization (mTICI = 0–2a), n (%)
|
5 (7.60)
|
0
|
5 (13.9)
|
0.145
|
|
NIHSS of post-MT 24 hour, median (range)
|
12 (0–37)
|
6 (0–17)
|
22 (5–37)
|
0[a]
|
|
Postprocedural sICH, n (%)
|
5 (7.60)
|
1 (3.3)
|
4 (11.1)
|
0.366
|
|
Dead, n (%)
|
19 (31.18)
|
0
|
19 (52.8)
|
0[a]
|
|
LOS (d), median (range)
|
12.5 (1–121)
|
10 (1–50)
|
17 (1–121)
|
0.046[a]
|
Abbreviations: IV, intravenous; LOS, length of stay; MT, mechanical thrombectomy;
mTICI, modified thrombolysis in cerebral infarction; NIHSS, National Institutes of
Health Stroke Scale; rt-PA, recombinant tissue-type plasminogen activator; SD, standard
deviation; sICH, symptomatic intracerebral hemorrhage.
a Statistical significance.
For patients with successful reperfusion (mTICI = 2b–3), our results also showed males
and age over 60 years were predominated, initial NIHSS mean was 19 (good outcome 14
vs. poor outcome 21, p = 0.001), which showed statistical significance. For comorbidity, history of smoking,
intravenous rt-PA administration, and mode of anesthesia showed no statistical significance,
except for the presence of PCoA which is 50/61 (82%) of our case and showed statistical
significance (96.7% vs. 67.7%, p = 0.004). Fifteen of 30 (50%) distal basilar artery occlusion cases showed good outcomes
while 10/31 (32.3%) of middle basilar artery occlusion cases showed poor outcomes,
which is statistically significant (50% vs. 32.3%, p = 0.023). About the timing of intervention, primary procedural MT, first-pass success,
rescue procedure, reperfusion grade, post-procedural sICH, stroke subtype, and clot
pathology, no statistically significant relation was observed. Lastly, patients who
were clinically the same or Additionally, for the patients with stable or worsening
clinical symptoms after treatment compared with the initial NIHSS within 24 hours
presenting poor outcomes with statistically significant. A good clinical outcome has
a shorter length of hospital stay (10 days) while poor clinical outcome is associated
with longer length of hospital stay (20 days), which showed statistical significance
(10 vs. 20 days, p = 0) ([Table 2]).
Table 2
Comparison between good and poor outcomes at 90 days in patients with successful revascularization
after mechanical thrombectomy
|
Variables
|
Overall
(N = 61)
|
Good outcome (n = 30)
|
Poor outcome (n = 31)
|
p-Value
|
|
Male, n (%)
|
35 (57.40)
|
17 (56.70)
|
18 (58.10)
|
0.912
|
|
Age > 60, n (%)
|
38 (62.30)
|
18 (60)
|
20 (64.50)
|
0.718
|
|
Initial NIHSS score, mean (range)
|
19 (4–32)
|
14 (4–31)
|
21 (8–32)
|
0.001[a]
|
|
Comorbidity
|
|
Diabetes mellitus, n (%)
|
27 (44.30)
|
11 (36.70)
|
16 (51.60)
|
0.24
|
|
Hypertension, n (%)
|
56 (91.80)
|
26 (86.70)
|
30 (96.60)
|
0.195
|
|
Dyslipidemia, n (%)
|
36 (59)
|
17 (56.70)
|
19 (61.30)
|
0.714
|
|
Atrial fibrillation, n (%)
|
30 (49.20)
|
18 (60)
|
12 (38.70)
|
0.096
|
|
Old cerebrovascular accident, n (%)
|
16 (26.20)
|
8 (26.70)
|
8 (25.80)
|
0.939
|
|
Coronary artery disease, n (%)
|
11 (18)
|
4 (13.30)
|
7 (22.60)
|
0.348
|
|
History of smoker, n (%)
|
18 (29.50)
|
9 (30)
|
9 (29)
|
0.934
|
|
IV rt-PA administration, n (%)
|
22 (36.10)
|
14 (46.70)
|
8 (25.80)
|
0.09
|
|
Cord sign on NCCT, n (%)
|
44 (72.10)
|
20 (66.70)
|
24 (77.40)
|
0.353
|
|
PCoA patency presentation, n (%)
|
50 (82)
|
29 (96.70)
|
21 (67.70)
|
0.004[a]
|
|
pc-ASPECTS, median (range)
|
9 (5–10)
|
9 (6–10)
|
8 (5–10)
|
0.14
|
|
General anesthesia, n (%)
|
53 (86.90)
|
24 (80)
|
29 (93.50)
|
0.147
|
|
Occlusion site
|
|
Distal BA, n (%)
|
23 (37.70)
|
15 (50)
|
8 (25.80)
|
0.023[a]
|
|
Middle BA, n (%)
|
18 (29.50)
|
8 (26.70)
|
10 (32.30)
|
|
Proximal BA, n (%)
|
11 (18)
|
6 (20)
|
5 (16.10)
|
|
VA, n (%)
|
9 (14.80)
|
1 (3.3)
|
8 (25.80)
|
|
Timing of intervention
|
|
Onset to puncture, median (range)
|
285 (95–895)
|
325.50 (110–895)
|
244 (95–880)
|
0.323
|
|
Onset to recanalization, median (range)
|
350 (129–1,050)
|
411 (170–960)
|
296 (129–1,050)
|
0.466
|
|
CT to puncture, median (range)
|
88 (32–400)
|
93.5 (40–400)
|
81 (32- 205)
|
0.126
|
|
Puncture to recanalization, median (range)
|
45 (7–182)
|
41 (8–182)
|
52 (7–170)
|
0.767
|
|
Primary procedural MT
|
|
Contact aspiration MT, n (%)
|
31 (50.80)
|
17 (56.70)
|
14 (45.20)
|
0.396
|
|
Stent MT, n (%)
|
30 (49.20)
|
13 (43.30)
|
17 (54.8)
|
|
Solitaire stent retriever MT, n (%)
|
28 (93.30)
|
12 (92.30)
|
16 (94.10)
|
1
|
|
Trevo stent retriever MT, n (%)
|
2 (6.70)
|
1 (7.70)
|
1 (5.90)
|
|
First-pass success, n (%)
|
26 (42.60)
|
13 (43.30)
|
13 (41.90)
|
0.835
|
|
Rescue procedures, n (%)
|
35 (57.40)
|
17 (56.70)
|
18 (58.10)
|
0.913
|
|
Aspiration MT, n (%)
|
12 (19.70)
|
5 (16.70)
|
7 (22.60)
|
0.835
|
|
Stent retriever MT, n (%)
|
23 (37.70)
|
12 (40)
|
11 (35.50)
|
|
Incomplete reperfusion (mTICI = 2b), n (%)
|
23 (37.70)
|
12 (40)
|
11 (35.50)
|
0.718
|
|
Completed reperfusion (mTICI = 3), n (%)
|
38 (62.30)
|
18 (60)
|
20 (64.50)
|
|
Postprocedural sICH, n (%)
|
4 (6.60)
|
1 (3.30)
|
3 (9.70)
|
0.612
|
|
Dead, n (%)
|
16 (26.2)
|
0
|
16 (51.6)
|
0[a]
|
|
Stroke subtype (TOAST classification)
|
|
Cardioembolic, n (%)
|
41 (67.20)
|
20 (66.70)
|
21 (67.70)
|
0.223
|
|
Large vessel arterosclerosis (ICAD), n (%)
|
17 (27.90)
|
7 (23.30)
|
10 (32.30)
|
|
Undetermined etiology, n (%)
|
3 (4.90)
|
3 (10)
|
0 (0)
|
|
Clot pathology
|
|
Fibrin thrombus, n (%)
|
7 (11.5)
|
2 (6.70)
|
5 (16.10)
|
0.395
|
|
Recent thrombus, n (%)
|
44 (72.10)
|
24 (80)
|
20 (64.50)
|
|
Post-24-h NIHSS equally or increased, n (%)
|
25 (41)
|
5 (16.70)
|
20 (64.5)
|
0[a]
|
|
LOS (d), median (range)
|
13 (1–121)
|
10 (1–50)
|
20 (1–121)
|
0[a]
|
Abbreviations: BA, basilar artery; CT, computed tomography; ICAD, intracranial atherosclerotic
disease; IV, intravenous; LOS, length of stay; MT, mechanical thrombectomy; mTICI,
modified thrombolysis in cerebral infarction; NCCT, noncontrast computed tomography;
NIHSS, National Institutes of Health Stroke Scale; pc-ASPECTS, posterior circulation
Alberta Stroke Program Early CT Score; PCoA, posterior communicating artery; rt-PA,
recombinant tissue-type plasminogen activator; sICH, symptomatic intracerebral hemorrhage;
VA, vertebral artery.
a Statistical significance.
In multivariate logistic regression analysis with binary logistic regression method,
distal basilar artery occlusion (adjusted odds, 9.393; 95% confidence interval, 1.176–75.018;
p = 0.035) and PCoA patency presentation (adjusted odds, 17.397; 95% confidence interval,
1.449–208.939; p = 0.024) were significantly related to 90 days with good outcome after successful
reperfusion ([Table 3] and [Fig. 3]).
Table 3
Association between prognosis factor and outcome in patients with acute posterior
circulation stroke
|
Risk factors
|
Good outcome
|
Poor outcome
|
Adjusted odds (95% CI lower–upper limit)
|
p-Value
|
|
Initial NIHSS < 20 (n = 31)
|
22 (73.5%)
|
9 (29%)
|
1.731 (0.247–12.139)
|
0.581
|
|
IV rt-PA administration (n = 22)
|
14 (46.7%)
|
8 (25.8%)
|
2.621 (0.449–15.299)
|
0.284
|
|
MRI brain performed (n = 14)
|
9 (30%)
|
5 (16.1%)
|
1.078 (0.152–7.651)
|
0.940
|
|
Distal basilar artery occlusion (n = 23)
|
15 (50%)
|
8 (25.8%)
|
9.393 (1.176–75.018)
|
0.035[a]
|
|
PCoA patency presentation (n = 50)
|
29 (96.7%)
|
21 (67.7%)
|
17.397 (1.449–208.939)
|
0.024[a]
|
|
Aspiration MT (n = 31)
|
17 (56.7%)
|
14 (45.2%)
|
3.188 (0.554–18.342)
|
0.194
|
Abbreviations: CI, confidence interval; IV, intravenous; MRI, magnetic resonance imaging;
MT, mechanical thrombectomy; NIHSS, National Institutes of Health Stroke Scale; PCoA,
posterior communicating artery; rt-PA, recombinant tissue-type plasminogen activator.
a Statistical significance.
Fig. 3 Multivariate assessment for the association between prognosis factors and good outcome
in patients with acute posterior circulation stroke.
Discussion
The effectiveness of MT for acute posterior circulation stroke patients was achieved
in up to 92.4% by successful recanalization (mTICI 2b–3); of those, good clinical
outcome (mRS 0–2) was 45.45%. The reason for 45.45% of good clinical outcomes despite
92.4% successful recanalization was probably due to a natural history of posterior
circulation usually presented with higher initial NIHSS which is associated with poor
outcome. Moreover, our study demonstrates a higher successful recanalization rate
and good outcomes compared with other studies.[4]
[12] This corresponded with a previous study in China reporting that successful recanalization
accounted for 89.9% with 36.2% good outcome at 90 days.[6] Based on the initial NIHSS, the present study demonstrated that it was significantly
associated with good outcome. Correspondingly, a former study in the U.S. indicated
that the NIHSS score is a factor associated with a favorable prognosis.[7] Moreover, the ENDOSTROKE study, based on the univariate analysis, showed that the
NIHSS score, absence of hemorrhagic transformation, and MRI compared with CT in the
preoperative imaging were significantly relevant to favorable outcomes. Meanwhile,
the multivariate analysis revealed that the NIHSS score, implementation of MRI, and
the presence of favorable collateral circulation were significant parameters.[4] This study showed statistical significance only on NIHSS score, suggesting that
low initial NIHSS score contribute to a good outcome. Khatibi et al reported that
the use of MRI as the initial imaging modality can prolong time to intervention in
case of posterior circulation stroke, though it provides valuable additional prognostic
information which can lead to a more informed approach to acute stroke intervention
decision.[8] In addition, MRI was also useful to select patients for this study to get good outcome.
However, such association was not statistically significant. It might be due to the
limited number of patient participation.
pc-ASPECTS on diffusion-weighted imaging (DWI) in predicting functional outcome in
acute posterior circulation ischemic stroke patients appeared to be a powerful marker
according to the report of Tei et al and Garg and Biller.[9]
[10] It was documented that DWI pc-ASPECTS of 8 or higher is the only independent predictor
for favorable outcomes in patients with acute basilar artery occlusion.[11] In our study, provided that MRI was unavailable, single-phase CTA or multiphase
CTA were acceptable for deciding if MT should be conducted in those without clinical
signs of brainstem infarction and area of large infarction from noncontrast CT.
The presence of bilateral PCoA on pretreatment CTA appears to be associated with more
decent outcome in patients affected with basilar artery occlusion and received endovascular
treatment.[13] A previous study demonstrated that an appearance of one or more patent PCoA is associated
with a lower risk of poor outcome.[10] This corresponded to the current study that the presence of PCoA patency correlated
with good outcome. By retrospective review, PCoA was used to visualize the PCoA artery
of pre-MT CTA and/or cerebral angiography. The relationship between clot location
and outcome after basilar artery thrombolysis was also reported by Cross et al, who
found that the single best predictor of survival after basilar thrombosis and intra-arterial
thrombolysis is distal clot location.[14] Likewise, the present study also indicated that the basilar artery occlusion is
significantly associated with good outcome, whereas the occlusion at the middle basilar
artery resulted in poor outcome. According to the etiology of clot defined by TOAST's
classification, our cases correlated with cardioembolism which the distal basilar
artery occlusion was easier to recanalize; meanwhile, that at proximal and middle
basilar artery is in association with intracranial atherosclerotic disease which was
difficult and required rescue procedures for recanalization.
In the multivariate analysis, distal basilar artery occlusion and presence of PCoA
patency were significantly related to good outcome after successful recanalization
as shown in [Table 3] and [Fig. 3]. In addition, aspiration MT, intravenous rt-PA administration, initial NIHSS below
20, and MRI brain image were associated with a good outcome but not significant statistically.
The direct-aspiration first-pass technique may be a good option as the first-line
strategy to improve the rate of complete reperfusion and reduce procedure duration.[15] Our results in the current study also demonstrated a good outcome with aspiration
since the primary MT with first-pass success was 42.6%. However, the aspiration and
outcome from stent retrieval MT in this study was not statistically significant.
A good outcome, in this study, was not influenced by age, gender, comorbidity, intravenous
rt-PA administration, mode of anesthesia, timing of intervention, primary procedure,
rescue procedure, stroke subtype, and clot pathology. The overall safety outcome in
the present study was 7.6% for postprocedural sICH and 31.18% for mortality, which
were similar to 6.3% for postprocedural sICH and 25% for mortality as reported by
Gilberti et al.[11] However, those lower proportions might be due to the fewer patients than those in
our study.
Conclusion
The present study demonstrated the efficient outcomes of MT in patients with acute
posterior circulation stroke. Factors associated with good outcome were distal basilar
artery occlusion and PCoA patency presentation which also helped reduce the hospitalization
length in our patient.
