Prevalence and Outcomes of Medium Vessel Occlusions With Discrepant Infarct Patterns

Background and purpose: The prognosis of medium vessel occlusions (MeVOs), that is, M2/3 middle cerebral artery, A2/3 anterior cerebral artery, and P2/3 posterior cerebral artery occlusions, is generally better compared with large vessel occlusions, since brain ischemia is less extensive. However, in some MeVO patients, infarcts are seen outside the territory of the occluded vessel (MeVO with discrepant infarcts). This study aims to determine the prevalence and clinical impact of discrepant infarct patterns in acute ischemic stroke due to MeVO.

Methods: We pooled data of MeVO patients from INTERRSeCT (Identifying New Approaches to Optimize Thrombus Characterization for Predicting Early Recanalization and Reperfusion With IV Alteplase and Other Treatments Using Serial CT Angiography) and PRove-IT (Precise and Rapid Assessment of Collaterals Using Multi-Phase CTA in the Triage of Patients With Acute Ischemic Stroke for IA Therapy)-2 prospective cohort studies of patients with acute ischemic stroke. The combination of occlusion location on baseline computed tomography angiography and infarct location on follow-up computed tomography/magnetic resonance imaging was used to identify MeVOs with discrepant infarct patterns. Two definitions for discrepant infarcts were applied; one was more restrictive and purely based on infarct patterns of the basal ganglia, whereas the second one took cortical infarct patterns into account. Clinical outcomes of patients with versus without discrepant infarcts were summarized using descriptive statistics. Logistic regression was performed to obtain adjusted effect size estimates for the association of discrepant infarcts and good outcome, defined as a modified Rankin Scale score of 0 to 2, and excellent outcome (modified Rankin Scale score 0-1).

Results: Two hundred sixty-two patients with MeVO were included in the analysis. The prevalence of discrepant infarcts was 39.7% (definition 1) and 21.0% (definition 2). Patients with discrepant infarcts were less likely to achieve good outcome (definition 1: adjusted odds ratio, 0.48 [95% CI, 0.25-0.91]; definition 2: adjusted odds ratio, 0.47 [95% CI, 0.22-0.99]). When definition 1 was applied, patients with discrepant infarcts were also less likely to achieve excellent outcome (definition 1: adjusted odds ratio, 0.55 [95% CI, 0.31-0.99]; definition 2: adjusted odds ratio, 0.62 [95% CI, 0.31-1.25]).

Conclusions: MeVO patients with discrepant infarcts are common, and they are associated with more severe deficits and poor outcomes.