Microbleeds, cerebral hemorrhage, and functional outcome after endovascular thrombectomy

Objective—To determine whether the presence, number, and distribution of
cerebral microbleeds (CMBs) on pretreatment MRI scans are associated with
an increased risk of intracerebral hemorrhage (ICH) or poor functional
outcome following endovascular thrombectomy (EVT) for acute
ischemic stroke (AIS). Methods—We analyzed prospectively
collected data of consecutive patients treated by EVT for AIS, in a
comprehensive stroke center where MRI is the first-line pretreatment
imaging. Neuroradiologists blinded to clinical data rated CMBs on T2*
sequence using a validated scale. We investigated associations of
pre-treatment CMB presence, burden (1, 2–4, and ≥5), and presumed
pathogenesis with ICH and poor 3-month functional outcome (modified Rankin
score >2). Results—Among 513 patients, 281 (54.8%) had a poor
outcome and 89 (17.3%) had ≥1 CMBs. A total of 190 (37%) patients
experienced ICH, in which 66 (12.9%) were symptomatic. CMB burden was
associated with worse outcome in a univariable analysis (odds ratio [OR],
1.18; 95% confidence interval [CI], 1.03–1.36 per 1-CMB increase; P=0.02),
but significance was lost after adjustment for age, sex, baseline stroke
severity, hypertension, diabetes mellitus, atrial fibrillation, prior
antithrombotic medication, intravenous thrombolysis, and reperfusion
status (OR, 1.05; 95% CI, 0.92–1.20 per 1-CMB increase; P=0.50). Results
remained nonsignificant when taking into account CMB location or presumed
underlying vasculopathy. CMB presence, burden, location, nor presumed
underlying vasculopathy was independently associated with ICH.
Conclusions—Poor outcome or ICH was not associated with CMB presence or
burden on pre–EVT MRI after adjustment for confounding factors. Excluding
such patients from reperfusion therapies is unwarranted.