Effects of prehospital blood pressure on 90-day functional outcomes in patients with acute ischemic stroke due to large vessel occlusion

BACKGROUND: Prehospital blood pressure (BP) could influence cerebral circulation and outcomes in acute large vessel occlusion (LVO). We investigated the association between prehospital BP and 90-day functional outcomes and explored effect modification by endovascular thrombectomy (EVT). METHODS: We analyzed 1,106 patients with acute LVO transported by emergency medical services between 2018 and 2024. Prehospital systolic BP (SBP, mmHg) measured at the scene was categorized into four groups: <120, 120-149, 150-179, and ≥180 groups. The primary outcome was a 90-day modified Rankin Scale (mRS) score of 0-2. Secondary outcomes included mRS 0-3 and hemorrhagic complications. Subgroup analyses for the primary outcome were also conducted. RESULTS: Mean age was 79 years, and 51% were male; 60% underwent EVT. The SBP <120, 120-149, 150-179, and ≥180 groups included 120, 403, 403, and 180 patients, respectively. Cardioembolic stroke was most common and decreased with increasing SBP. Compared with SBP <120 mmHg, SBP ≥180 mmHg was associated with lower odds of mRS 0-2 (adjusted OR, 0.43; 95% CI, 0.22-0.84; p=0.01), with similar trends for mRS 0-3. This association was significant in EVT-treated patients but not in non-EVT patients (interaction p=0.007). Hemorrhagic complications were similar across groups. CONCLUSIONS: Elevated prehospital SBP (≥180 mmHg) was associated with worse 90-day functional outcomes in acute LVO, especially following EVT. These findings highlighted the potential clinical relevance of prehospital BP assessment in patients with LVO. Further investigation should be considered for prehospital BP status in addition to the in-hospital managements.