Late Endovascular Treatment for Ischemic Stroke with Moderate to Large Infarct Volume is Associated with a Better Clinical Prognosis

The concept of "time is brain" is crucial for the reperfusion therapy of ischemic stroke. However, the Infarct Growth Rate (IGR) varies among individuals, which is regarded as a more powerful factor than the time when determining infarct volume and its association with clinical outcomes. For stroke patients with a similar infarct volume, a longer time from stroke Onset to Imaging (OTI) correlates with a lower IGR, which may indicate a better prognosis. This study aimed to compare the prognoses of patients with anterior circulation stroke who received Endovascular Treatment (EVT), specifically comparing early EVT vs. late EVT. We analyzed 255 patients with acute anterior circulation stroke due to large vessel occlusion and who have successfully undergone recanalization after EVT. All patients were divided into the late (OTI≥6 hours) and early (<6 hours) time window groups and compared. The primary outcome was moderate functional prognosis, defined as a modified Rankin Scale (mRS) ≤3 at 90 days. The secondary outcome was No Significant Infarct Expansion (NSIE), defined as a reduction of less than 2 points on the Alberta Stroke Program Early CT Score (ASPECTS). In the moderate to large infarct subgroup, the late time window EVT was independently associated with a higher rate of moderate functional outcome (P =0.007) and NSIE (P =0.001); mediation analysis showed that NSIE partially mediated the effects of the late time window EVT on moderate functional outcome (coefficient: 0.112, 95% CI: 0.051 to 0.239, P =0.011); however, these associations were not consistent in the small infarct group. For anterior circulation stroke patients who received EVT according to current guidelines, those with moderate to large infarct volume and having a longer OTI had better clinical outcomes than those who had a shorter OTI and were more suitable for EVT.