WSO - February 2023 - 222

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International Journal of Stroke 18(2)
Keywords
First pass effect, multi-pass effect, large vessel occlusion, posterior circulation stroke
Received: 18 November 2021; accepted: 24 February 2022
Introduction
Complete successful recanalization, defined as the presence
of a modified Thrombolysis In Cerebral Infarction
(mTICI) of 3, has been widely associated with maximal
benefits in functional outcome at 3 months.1,2
The first pass effect (FPE), defined as the achievement
of mTICI 3 in a single pass of the endovascular thrombectomy
device, has been described as an independent predictor
of good outcomes in patients with large vessel occlusion
(LVO) undergoing endovascular thrombectomy (EVT) in
anterior circulation stroke.3,4 Some specific variables, such
as the use of a balloon guide catheter and thrombus location,
have been related to this FPE.5
Despite the lack of clear evidence of the clinical benefit of
EVT in posterior circulation large vessel occlusion (PC-LVO),
current guidelines recommend treating these patients endovascularly.6-9
The factors associated with FPE on PC-LVO and its
impact on functional outcome is still poorly understood.10-13
We aimed to study the frequency, characteristics, and
predictors of FPE on a PC-LVO population as well as the
factors associated with functional independence at 3 months.
Method
Study population
CICAT (Codi Ictus Catalunya) is a government-mandated,
prospective, hospital-based dataset in which all stroke codes
are included in Catalonia. From January 2016 to January
2020, a total of 24,553 consecutive stroke codes were
reported. A total of 3167 EVT were performed, and 41
(1.29%) patients were excluded from the analysis due to lack
of 3 months follow-up. Finally, 265 patients with pc-LVO
who were fully studied were included in the study (Figure 1).
All patients included in this study have an angiographic
confirmation of acute arterial occlusion of the basilar artery,
posterior cerebral artery (PCA), or intracranial vertebral
artery, less than 12 hours from stroke onset, a baseline pcASPECTS
⩽6 and a National Institute of Health Stroke
Score (NIHSS)⩾6 or high disabling symptomatology.
The purpose of this study was approved by the governmental
Catalan Review Board and the local Ethical
Committee (codi CEIM 2021.071).
Variables
We collected demographical, clinical, and radiological data
from all the patients who underwent EVT with at least one
device pass.
International Journal of Stroke, 18(2)
In the current study, complete successful recanalization
was defined by the presence of a modified Thrombolysis In
Cerebral Infarction (mTICI) of 3 in the final cerebral angiography.
FPE was considered if mTICI 3 was achieved in
the first pass of the device. All other patients were classified
in " non-FPE " group. For a second analysis, if mTICI 3
was achieved beyond the first pass, it was defined as multipass
effect (MPE).
Neurological status was assessed by certified stroke
neurologists at admission and during the whole followup
by using the NIHSS, and all endovascular procedures
were completed by neurointerventionsts and
neuroanesthesiologists.
The occlusion site was evaluated by computed tomography
angiography and confirmed by cerebral angiography
run prior to the EVT.
Functional outcome at 3 months was centrally assessed
by blinded evaluators of the Catalan Stroke Program using
a structured telephone interview of the modified Rankin
Score (mRS).
The primary outcome was the rate of functional independence
(mRS score ⩽ 2) at 3 months. Secondary outcomes
were anesthesia choice, technique during EVT, and
mortality at 3 months.
Statistical analysis
The baseline characteristics were compared using the Student
t test or the Mann-Whitney U test for continuous variables
and the χ2 test for categorical variables. Univariate analyses
were performed to study variables associated with clinical
outcome and FPE. Continuous variables are shown as mean
(standard deviation, SD) or median [interquartile intervals]
and were compared with the Student t test, analysis of variance,
Mann-Whitney, or Kruskal-Wallis tests as appropriate.
Categorical variables were reported as proportions.
Logistic regression was used to study the association
between FPE and the primary outcome and to adjust for
possible confounders. Variables showing a trend toward
significance (p value < .1) were entered in the multivariable
logistic models.
Data were analyzed with SPSS version 22.0 software,
and all tests were performed with a 5% significance level.
Results
Two hundred and sixty-five patients were included in the
study. The median age was 72 [63-80] years and 103
(38.9%) were female.
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