Tissue at risk in acute stroke patients treated beyond 8 h after symptom onset

The decision on thrombolytics administration is usually based on a generalized, rigid time-based rule rather than an individualized evaluation of the "tissue at risk of infarction" which is the target of the recanalization therapies. The goals of our article are to assess whether there is tissue at risk of infarction in a group of acute stroke patients treated beyond 8 h after symptom onset and to investigate the baseline imaging and clinical features that predict the fate of this tissue at risk. We retrospectively reviewed a series of patients with acute ischemic stroke treated with endovascular recanalization therapies beyond 8 h after symptom onset. The tissue at risk was calculated as the difference between the infarct volumes on baseline and follow-up imaging (infarct growth). We analyzed the epidemiological distribution of infarct growth, and we performed a multivariate regression analysis to identify the baseline variables that predict infarct growth. Our study group included 75 patients (65 +/- 13.8 years, baseline National Institutes of Health Stroke Scale 14 +/- 4.9, time to treatment 15.2 +/- 8.7 h). The mean infarct growth was 78.6 +/- 95.0 cc (p < 0.001), and, overall, the infarct growth was greater when the baseline volume of infarct tissue was small (p < 0.001) and in the case of a unsuccessful arterial recanalization (p = 0.001). There is potentially salvageable ischemic tissue at risk in acute stroke patients treated beyond 8 h after symptom onset.