Systolic blood pressure modifies the effect of endovascular thrombectomy in acute ischemic stroke: a mediation analysis

Background: Systolic blood pressure (BP) is a key factor in the outcomes of patients with acute ischemic stroke (AIS) receiving endovascular thrombectomy (EVT). However, the factors that mediate the association between BP and clinical outcome are unclear.

Methods: Consecutive patients with AIS in the anterior circulation underwent continuous blood pressure monitoring for 24 hours. The 3-month modified Rankin scale (mRS) score was defined as the clinical functional outcome. The systolic BPI indices (BPIs) were successive variation (SV), standard deviation (SD), variability independent of mean blood pressure (VIM) and 24-hour mean BP. Regression analysis was used to assess the correlation between different BPIs and functional outcome, whereas mediation analysis was employed to assess the potential mediating effects of baseline risk factors through BP on functional outcome.

Results: A total of 140 of 292 patients (47.9%) achieved functional independence, and 87 (29.8%) experienced hemorrhagic transformation (HT). A history of stroke or hypertension and NIHSS score at onset were associated with SD and VIM (P<0.05). BP variation (BPV) was still strongly associated with functional outcome after adjustment for different risk factors. Mediation analysis revealed that stroke affected functional outcome by affecting BPV, while the hypertension history affected functional prognosis by impacting the 24-hour mean BP and BPV. In addition, higher NIHSS scores were associated with increased BPV, whereas increased BPV was correlated with a greater proportion of unfavorable outcome.

Conclusions: To our knowledge, this study is the first to explore the mediating effects of different BPIs on the relationships between risk factors and functional outcome and may provide new insights and potential mechanisms for improving AIS prognosis.