Reperfusion Within 6 Hours Outperforms Recanalization in Predicting Penumbra Salvage, Lesion Growth, Final Infarct, and Clinical Outcome

Background and Purpose-The relative merits of reperfusion versus recanalization to predict tissue and clinical outcomes in anterior circulation stroke have been previously assessed using data acquired > 12 hours postonset. To avoid late-occurring confounders such as non-nutritional reperfusion, futile recanalization and no-reflow phenomenon, we performed ultraearly assessment of reperfusion and recanalization. Methods-From a multicenter prospective database, 46 patients with acute magnetic resonance angiography-visible occlusion and in whom both reperfusion and recanalization were assessed on follow-up magnetic resonance imaging <= 6 hours of symptom onset were identified. Multiple linear regressions modeled salvaged penumbra, diffusion-weighted imaging lesion growth, and final infarct at 1 month using baseline clinical and imaging parameters and acute reperfusion or recanalization. Best predictors were determined with the Akaike information criterion. Univariate and multivariate logistic regressions identified the clinical and imaging predictors of clinical outcome. Results-Admission magnetic resonance imaging showed M1 occlusion in 15 (33%) patients; median penumbra volume was 13.4 mL. Acute reperfusion was observed in 27 (59%) patients; 42% of nonrecanalized patients demonstrated reperfusion. The dichotomized classification of reperfusion and recanalization was discordant (P=0.0002). Reperfusion <= 6 hours was a significant (P<0.05) predictor of increased penumbra salvage, reduced lesion growth, and final infarct size. Recanalization did not improve model accuracy. Reperfusion, but not recanalization, was significantly associated with good clinical outcome in logistic regressions. Conclusions-Reperfusion <= 6 hours was consistently superior to recanalization in predicting tissue and clinical outcome. Reperfusion without recanalization was frequent and probably related to retrograde reperfusion through leptomeningeal collaterals. Acute reperfusion was the strongest predictor of, and may therefore, represent a reliable surrogate for, clinical outcome.