Objective:

This study evaluated the impact of pre-hospital blood pressure (BP) on infarct volume and perfusion parameters, in large vessel occlusion acute ischemic stroke (LVO-AIS) patients undergoing mechanical thrombectomy (MT). 

Background:

Following a LVO-AIS there is an important disruption in cerebral autoregulation (CA), making optimal BP critical to maintain adequate cerebral perfusion. While prior research links intraprocedural BP drops and high post-thrombectomy BP to poor outcomes, data on pre-hospital hemodynamics remain limited. 

Design/Methods:

This retrospective observational study included data of LVO-AIS patients from two comprehensive stroke centers from 01-2018 to 12-2021. Inclusion criteria: >18 years, anterior circulation LVO, and >3 pre-hospital BP recordings. BP was measured non-invasively, and mean SBP(mSBP) and MAP(mMAP) were calculated. Collateral status was evaluated via hypoperfusion intensity ratio (HIR, Tmax 10s/Tmax 6s). The main outcome was initial infarct volume (IIV, defined as admission rCBF<30% on CTP). Other outcomes included mismatch volume and ratio, early infarct growth ratio (EIGR, rCBF<30%/stroke onset to CTP time). We used multivariable linear regression, interaction, and subgroup analysis.

Results:

171 patients were included. Initial CTP paremeters included: median IIV of 6cc, Tmax>6s of 103cc, Tmax>10s , and HIR 0.38. We found that for each unit increase in mMAP, IIV decreased by 10%(adjusted coefficient [aCoeff] 0.90, p<0.001), and the EIGR decreased in 9%(aCoeff. 0.91, p<0.001). For each unit increase in mSBP, mismatch volume increased in 3% (aCoeff. 1.03, p=0.021) and EIGR decreased in 3% (aCoeff. 0.97, p=0.035). In subgroup analysis, the association between higher BP and lower IIV persisted exclusively in patients with good collaterals. 

Conclusions:

Elevated pre-hospital BP wwas associated with reduced IIV, increased mismatch volume, and slower infarct growth, primarily in patients with good collateral status. These findings underscore the need for prospective studies to better evaluate the optimal BP thresholds in the pre-hospital settings and the role of collateral status in influencing stroke outcomes.