Objective:

To determine the impact of chronic white matter lesions (WML) on functional outcomes in patients with acute stroke who underwent endovascular thrombectomy (EVT).

Background:

The evidence regarding the impact of chronic WML on functional outcomes after EVT is mixed.

Design/Methods:

A prospective stroke center registry (10/2019-06/2021) of consecutive adult patients with acute stroke was queried for patients with ICA or M1 occlusions who had undergone magnetic resonance imaging (MRI). Multivariable logistic regression was used to estimate the relationship between age, Alberta Stroke Program Early Computed Tomography Scale score, National Institutes of Health Stroke Scale, occlusion location, and successful recanalization (thrombolysis in cerebral infarction score of 2b-3 versus 0-2a or no thrombectomy) on good functional outcome (90-day mRS 0-2). Mediation analysis was used to estimate the effect of WML severity on age as a predictor of good functional outcome following successful recanalization.

Results:

Among the 121 included patients, the median age was 67y (IQR 58-77), 49 (40.5%) were female, and 39 (32.2%) had a Fazekas score of 2 or 3. In unadjusted regression, age was associated with WML severity (step 1: OR 1.03, 95% CI 1.02-1.04, p<0.001), and age was associated with an unfavorable 90-day mRS (step 2: proportional OR 0.98, 95% CI 0.95-0.99, p = 0.027). WML severity was also associated with 90-day mRS (step 3: OR 0.74, 95% CI 0.52-1.06, p=0.096). In multivariable regression, the total effect of age on unfavorable shift in 90-day mRS remained significant (OR 0.96, 95% CI 0.94-0.98, p<0.001), with a trend toward a persistent indirect mediator effect of WML (p=0.084). The mediator WML severity explained 23% of the association of age with 90-day mRS.

Conclusions:

In this single center analysis, WML burden partially mediated the effect of age on functional recovery in acute stroke.