White Matter Hyperintensity-Adjusted Critical Infarct Thresholds to Predict a Favorable 90-Day Outcome.

BACKGROUND AND PURPOSE There is increasing interest in defining stroke lesion volume thresholds to predict poststroke outcome. However, there is a paucity of data on factors that impact the association between critical infarct thresholds volume and outcome. We sought to determine whether lesion thresholds best predicting outcome depend on the degree of preexisting white matter hyperintensity (WMH) lesion burden. METHODS Magnetic resonance imaging infarct volumes were quantified in 414 consecutive patients with anterior circulation ischemic strokes evaluated between January 2014 and December 2014. The WMH lesion volume was graded according to the Fazekas scale and dichotomized to absent to mild versus moderate to severe. Receiver operator characteristics curves were calculated to determine the infarct volume threshold best predicting the 90-day outcome. Multivariable logistic regression was used to determine whether the critical lesion thresholds independently predicted a favorable 90-day outcome after adjusting for pertinent confounders. RESULTS The infarct volumes thresholds predicting the 90-day outcome for the entire cohort (standard thresholds) were ≤29.5 mL (modified Rankin scale [mRS] 0-1), ≤29.9 mL (mRS 0-2), and ≤34.1 mL (mRS 0-3). For patients with absent-to-mild WMH lesion burden, WMH-adjusted critical infarct thresholds were significantly greater than the standard infarct thresholds. In the fully adjusted multivariable regression models, the WMH-adjusted infarct thresholds correctly predicted the outcome to a similar degree as the standard thresholds. CONCLUSIONS In this proof-of-concept study, the WMH lesion burden impacted the critical outcome-predicting infarct thresholds. If confirmed, using a WMH-adjusted infarct threshold could allow defining patients that have a favorable outcome despite having relatively large infarct volumes.