BACKGROUND: The impact of lowering systolic blood pressure (SBP) following endovascular treatment (EVT) in acute large vessel occlusion stroke (LVOS) patients remains unclear. We aimed to explore the effect of the magnitude of SBP reduction (SBPr) after EVT on outcomes in LVOS patients. METHODS: We consecutively registered patients at three comprehensive stroke centres who had experienced EVT as a result of acute anterior circulation LVOS. SBPr was calculated as follows: (baseline SBP-mean SBP/baseline SBP)×100%. The 90-day modified Rankin Scale score ranging from 0 to 2 was defined as a favourable functional outcome. Based on CT scans obtained within 24 hours after procedure, symptomatic intracranial haemorrhage (sICH) was assessed according to the criteria of the European Cooperative Acute Stroke Study III. RESULTS: We enrolled 1080 patients, of which 908 (84.1%) had successful recanalisation. In the overall cohort, SBPr was correlated with lower odds of sICH (SBPr±10% as a reference, 20%-30%: OR 0.460
95% CI: 0.245 to 0.864
p=0.016
>
30%: OR 0.304
95% CI 0.123 to 0.749
p=0.010). In patients who achieved successful reperfusion, SBPr>
30% was correlated with higher odds of a poor outcome (SBPr±10% as a reference, OR 2.150
95% CI 1.268 to 3.645
p=0.004) and SBPr has a similar tendency towards reducing the incidence of sICH. In the subgroup analyses, baseline Alberta Stroke Programme Early CT (ASPECT) score (p CONCLUSION: Among patients with EVT, a significant drop in SBP may be related to a poor functional outcome and a reduced incidence of sICH. Baseline ASPECT score may be an important interacting factor in the association of SBPr with the 90-day outcome. This study provides new insights for individualised BP management in patients with EVT.