Role of recanalization in acute stroke outcome: rationale for a CT angiogram-based "benefit of recanalization" model.

BACKGROUND AND PURPOSE In acute middle cerebral artery (MCA) stroke, CT angiographic (CTA) source images (CTA-SI) identify tissue likely to infarct despite early recanalization. This pilot study evaluated the impact of recanalization status on clinical and radiologic predictors of patient outcomes. MATERIALS AND METHODS Of 44 patients undergoing CT/CTA within 6 hours of developing symptoms of proximal MCA ischemia, 19 patients achieved complete proximal MCA (MCA M1) recanalization. Admission National Institutes of Health Stroke Scale (NIHSS) score, onset-to-imaging time, CTA-SI Alberta Stroke Program Early CT Score, MCA M1 occlusion, cerebrovascular collaterals score, and CTA-SI lesion volume were correlated with 3- to 6-month follow-up modified Rankin Scale (mRS). We developed 2 stepwise regression models: one for patients with complete MCA M1 recanalization and one for patients without complete recanalization. RESULTS Complete and incomplete recanalization groups had similar median admission NIHSS scores (19 versus 19) and mean onset-to-imaging times (2.3 versus 1.9 hours) but different proportions of patients achieving mRS scores 0-2 (74% versus 40%; P = .04). The only independent predictors of clinical outcome in patients with complete recanalization were onset-to-imaging time and admission CTA-SI lesion volume (total model R(2) = 0.75; P = .01). The only independent predictors of outcome in patients with incomplete recanalization were admission CTA-SI lesion volume and NIHSS score (total model R(2) = 0.66; P = .007). CONCLUSION Regardless of recanalization status, admission CTA-SI lesion volume was associated with clinical outcome. Recanalization status did, however, affect which variables in addition to CTA-SI volume significantly impacted clinical outcome: time with complete recanalization and NIHSS with incomplete recanalization. This finding may support the development of a model predicting the potential clinical benefit expected with early successful recanalization.