Background and aims: Initiating blood pressure lowering prehospital may be harmful to patients with acute ischemic stroke (AIS). This study investigated the relationship between the magnitude of systolic blood pressure (SBP) and outcomes in patients with AIS.
Methods: INTERACT4 is ambulance-delivered trial investigating prehospital blood pressure lowering initiated within 2 hours of symptoms onset in Chinese patients suspected with acute stroke. Patients with ischemic stroke were selected in this post hoc analysis. The primary outcome was severe disability or death defined as a 3-month modified Rankin Scale score of 3-6. Secondary outcomes included the early neurological deterioration (END) defined as an increase of 4 or more points on the National Institutes of Health Stroke Scale (NIHSS) within 24 hours at admission. Logistic regression models were used to analyze the association between the magnitude of SBP and the outcomes.
Results: Among 1184 included participants (mean age 75 years, 43.4% female), the magnitude of SBP on the ambulance was not significantly associated with severe disability or death (odds ratio, 0.9959 [95% CI, 0.9890–1.0029]; P=0.252), However, a significant association was found in control group patients who have not received active BP lowering treatment on ambulance, with a larger reduction of SBP was associated with less severe disability or death (odds ratio, 0.9886 [95% CI, 0.9776–0.9996]; P=0.042). A larger reduction of SBP was also associated with less END (odds ratio, 0.9730 [95% CI, 0.9582–0.9881]; P=0.001).
Conclusion: Spontaneous SBP reduction on ambulance appears to be associated with better functional clinical outcomes in AIS.