Abstract
BACKGROUND:
Current
evidence provides limited support for the superiority of endovascular
thrombectomy (EVT) in patients with M2 segment middle cerebral artery
occlusion. We aim to investigate whether imaging features of M2 segment
occlusion impact the effectiveness of EVT.
METHODS:
We
conducted a retrospective cohort study from January 2017 to January
2022, drawing data from the CASE II registry (Computer-Based Online
Database of Acute Stroke Patients for Stroke Management Quality
Evaluation), which specifically documented patients with acute ischemic
stroke presenting with M2 segment occlusion undergoing reperfusion
therapy. Patients were stratified into the intravenous thrombolysis
(IVT) group (IVT alone) and EVT group (IVT plus EVT or EVT alone). The
primary outcome was a modified Rankin Scale score 0 to 2 at 90 days.
Secondary outcomes included additional thresholds and distribution of
modified Rankin Scale scores, 24-hour recanalization, early neurological
deterioration, and relevant complications during hospitalization.
Safety outcomes encompassed intracranial hemorrhagic events at 24 hours
and mortality at 90 days. Binary logistic regression analyses with
propensity score matching were used. Subgroup analyses were performed
based on the anatomic site of occlusion, including right versus left,
proximal versus distal, dominant/co-dominant versus nondominant, single
versus double/triple branch(es), and anterior versus central/posterior
branch.
RESULTS:
Among
734 patients (43.3% were females; median age, 73 years) with M2 segment
occlusion, 342 (46.6%) were in the EVT group. Propensity score matching
analysis revealed no statistical difference in the primary outcome
(odds ratio, 0.860 [95% CI, 0.611–1.209]; P=0.385) between the
EVT group and IVT group. However, EVT was associated with a higher
incidence of subarachnoid hemorrhage (odds ratio, 6.655 [95% CI,
1.487–29.788]; P=0.004) and pneumonia (odds ratio, 2.015 [95% CI, 1.364–2.977]; P<0.001).
Subgroup analyses indicated that patients in the IVT group achieved
better outcomes(NOT RECOVERY!) when presenting with right, distal, or nondominant
branch occlusion (Pall interaction<0.05).
CONCLUSIONS:
Our
study showed similar efficiency of EVT versus IVT alone in acute M2
segment middle cerebral artery occlusion. This suggested that only
specific patient subpopulations might have a potentially higher benefit
of EVT over IVT alone.
REGISTRATION:
URL: https://clinicaltrials.gov; Unique identifier: NCT04487340.
Five
randomized clinical trials issued in 2015 have confirmed the
superiority of endovascular thrombectomy (EVT) over medical management
in patients of acute ischemic stroke (AIS) with anterior large vessel
occlusion.1–5
However, patients with AIS enrolled in these trials mainly suffered
from proximal large vessel occlusion, including internal carotid artery
and M1 segment middle cerebral artery (MCA). In a meta-analysis of
individual patient data from the above trials, only 95 patients were
finally identified as M2 segment MCA occlusion,6 resulting in limited evidence for the efficacy of EVT in this subgroup.7
In
previous post hoc studies, EVT was considered an effective measure that
could improve(NOT GOOD ENOUGH!) clinical outcomes in acute M2 occlusion, when compared
with the control group who received medical management, that is,
intravenous thrombolysis (IVT) or antiplatelet therapy if IVT is not
applicable.8–10
However, patients with AIS with M2 occlusion who received EVT achieved
similar functional outcomes when compared with those with IVT alone,11 which might be due to a potentially beneficial treatment effect of IVT on more distal clot locations.12
Some
M2 segment is the dominant artery supplying blood to a large portion of
the MCA territory, presenting as severe neurological impairment and
sizable infarction after occlusion, but is as easily accessible for EVT
as the M1 segment.13–15
Hence, patients with the clot situated in the dominant M2 artery or in
close proximity to the furcation are likely to experience similar
benefits from EVT. We hypothesized that imaging features of M2 segment
MCA occlusions might affect the efficacy and safety of EVT, either with
or without IVT. In the current study, we sought to investigate whether
certain anatomic characteristics of M2 segment occlusions such as
location, size, anatomy, and number of vessels occluded could help
select patients who would benefit more from EVT than IVT alone.
