ABSTRACT NUMBER: ESOC2026A735 PREHOSPITAL SYSTOLIC BLOOD PRESSURE TRAJECTORY AND PROGNOSIS IN HYPCUTE STROKE: A POST-HOC ANALYSIS OF INTERACT4

Abstract Background and aims Uncertainty remains about the effects of prehospital blood pressure (BP) dynamics in hyperacute stroke. This study aimed to evaluate the association between prehospital systolic BP (SBP) trajectory and functional outcomes. Methods We performed a post-hoc analysis of the INTERACT4 trial, which included patients with suspected acute stroke causing motor deficit and elevated SBP (≥150 mmHg) assessed within 2 hours of symptom onset. The change in prehospital SBP (ΔSBP) was calculated as on-arrival SBP minus baseline SBP. Patients were categorized by direction of change into decrease (ΔSBP ≤−5 mmHg), stable (−5 to +5 mmHg), or increase (ΔSBP ≥+5 mmHg) groups. Additionally, the relative rate of SBP change was modeled as a continuous variable using restricted cubic splines. The primary outcome was functional status assessed by the modified Rankin scale (mRS) at 90 days. Results Among 2396 patients (mean age 69 years, 1478 [61.7%] male), the median time from symptom onset to randomization was 57 minutes (IQR 38–84). Compared with the decrease group, both stable (OR 1.29, 95% CI 1.07–1.57; p=0.01) and increase (OR 1.63, 95% CI 1.35–1.98; p<0.01) groups had significantly worse functional outcomes. When examined continuously, a U-shaped relationship emerged between the rate of SBP change and 90-day mRS, with the nadir of risk at −4.23% per 5 minutes. Conclusions A modest, gradual prehospital SBP decrease was associated with improved functional recovery. These findings establish an optimal SBP trajectory and inform the design of future trials testing risk-stratified and individualized SBP management. Conflict of interest Ruijuan Gang. nothing to disclose