Large-vessel intracranial occlusion portends poor prognosis
MedWire News: Nearly half of all ischemic strokes are due to large-vessel intracranial occlusion (LVO), a stroke subtype with a particularly poor prognosis, US study findings suggest.
The authors say that angiographic imaging of patients with suspected stroke is useful for identifying the affected vascular territory and better predicting patient outcomes.
Wade Smith (University of California, San Francisco, California) and co-workers assessed the frequency and characteristics of LVO-associated stroke in the Screening Technology and Outcome Project in Stroke (STOP Stroke) study. This was a prospective, imaging-based study performed at two academic medical centers serving an urban, multiethnic population.
The study enrolled 735 consecutive patients with suspected stroke who presented within 24 hours of symptom onset and underwent computed tomography and magnetic resonance angiography. In all, 579 events were adjudicated as stroke and 97 as transient ischemic attack (TIA).
LVO – defined as occlusion of the vertebral, basilar, carotid terminus, middle, or anterior cerebral arteries – was responsible for 267 (46%) strokes, 13 (13%) TIAs, and 41% of strokes and TIAs combined, report Smith et al.
Patients with LVO had significantly more severe strokes than those with non-LVO strokes, as indicated by a 7.8-point difference in mean National Institutes of Health Stroke Scale (NIHSS) scores on admission (12.2 vs 4.4).
Indeed, mean NIHSS scores varied widely according to the vascular territory involved, being highest with carotid terminus and basilar occlusions and lowest with more distal occlusions.
Patients with LVO had a 4.5-fold increased risk for death at 6 months versus patients with normal angiograms; LVO also negatively predicted a good outcome at 6 months (defined as a modified Rankin Scale score of ≤2), with an odds ratio of 0.33 versus no LVO.
In multivariate analysis, occlusion of the basilar and internal carotid terminus was a significant independent predictor of good outcomes at 6 months, with an OR of 0.18 versus no such occlusion. Other independent predictors of outcomes were baseline NIHSS scores and age.
Commenting on their results, Smith et al say that identifying patients with LVO on acute presentation “appears to be important” in view of the 4.5-fold increased risk for death and 3.0-fold decreased risk for a good outcome.
“The presence or absence of LVO likely adds independent information about prognosis, especially among patients with more severe strokes,” they write in the journal Stroke.
“Therefore, angiographic imaging appears to provide an additional independent variable beyond age and baseline NIHSS score to predict patient outcome when considering all information available to the treating physician at patient presentation."
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By Joanna Lyford