Differences between anterior and posterior circulation stroke in TOAST

Background and Purpose: Clinicians have tended to view anterior circulation (AC) and posterior circulation (PC) strokes as separate entities, with dif ferent underlying pathogenesis, natural histories, and potential responsive ness to interventions such as anticoagulation. We sought to explore differe nces between AC and PC stroke in the Trial of ORG 10172 in Acute Stroke Tre atment (TOAST). Methods: For patients enrolled in TOAST, prospective clinic al information was collected including outcome at 3 months. Data on vascula r distribution were obtained from the clinical impression of the investigat ors. Group comparisons for categorical data were performed using Fisher's e xact test. Independent sample t tests and analysis of covariance were used for all continuous data. Results: The analysis included 1,039 patients with AC stroke and 180 patients with PC stroke. There were fewer women in the P C than in the AC groups, but otherwise there were no differences in demogra phics, risk factors or stroke subtypes between the two groups. Headache (AC 8.7 %, PC 15%, p = 0.013) and vomiting (AC 3.5%, PC 17.8%, p < 0.001) were more common among PC patients. Mean baseline National Institutes of Health Stroke Scale (NIHSS) score was lower (less severe) among PC (6.1) than AC patients (9.5; p < 0.001). On univariate analysis, favorable outcome at 3 m onths was more common for PC patients in both the placebo group (PC 82%, AC 71%, p = 0.04) and heparinoid group (PC 87%, AC 73%, p = 0.005). However, multivariate analysis, controlling for gender, history of previous stroke a nd baseline NIHSS score, showed no difference in outcome between PC and AC stroke. For favorable outcome, there was no interaction between vascular di stribution and treatment category, suggesting that the effect of heparinoid did not differ between PC and AC strokes. Conclusion: Patients with PC str oke seem to have a better longterm outcome than do AC patients, but this di fference is no longer apparent when controlling for important prognostic va riables. PC patients did not show any particular benefit from anticoagulati on, and the efficacy of heparinoid did not vary between AC and PC stroke. W hile AC and PC patients do differ in some respects, it may be inappropriate to single out PC patients for anticoagulant treatment. Copyright (C) 2001 S. Karger AG, Basel.