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

Objective: 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.

Methods: 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).

Results: 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.

Conclusion: 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.