Associations between systolic blood pressure and infarct growth after thrombectomy for acute stroke: a retrospective observational study

Background The optimal blood pressure control strategy after mechanical thrombectomy (MT) is not well understood, especially for patients with successful recanalization. We hypothesized that low systolic blood pressure (SBP) after MT is associated with infarct growth (IG), even in patients with successful recanalization. Aims The aim of the present study was to clarify the relationships between IG and SBP parameters in patients treated with MT. Method Consecutive acute stroke patients who underwent emergent MT from September 2014 through December 2019 were retrospectively enrolled. Diffusion-weighted imaging (DWI) was performed on admission and approximately 24 hours after the procedure. IG was calculated as the difference between infarct volume on 24-h DWI and initial DWI. SBP from recanalization to 24-h DWI was used. The associations between IG and SBP parameters, including maximum, minimum, and mean SBPs and coefficient of variation (CV) of SBPs, were evaluated with multiple regression analyses. Results A total of 377 MT cases (225 male [60%], median age 76 [IQR 68-83] years, median NIHSS score 17 [10-23], median onset to initial DWI time 131 [79-350] min) were enrolled in this study. Successful recanalization modified the association between SBP parameters and IG (P for interaction < 0.05). In cases with successful recanalization (n = 314), SBP was recorded 7,007 times between recanalization and 24-h follow-up MRI. Minimum SBP from recanalization to 24-h DWI (standardized coefficient -0.144, 95% CI -0.269 to -0.019, p = 0.024, i.e., low minimum SBP was associated with higher IG) and coefficient of variation (CV) of SBP (0.122, 0.003 to 0.241, p = 0.045) were independently associated with IG, even after adjusting for various factors including age, sex, initial NIHSS score, baseline infarct volume, and symptomatic intracerebral hemorrhage. Conclusion Minimum SBP and CV of SBP after recanalization were associated with IG in consecutive acute stroke patients who underwent successful MT. IG is a sensitive imaging marker for evaluating the effect of post-procedural SBP, and extremely low SBP after MT should be avoided to mitigate IG. Data access statement Data are available upon reasonable request.