Predictors of functional outcome following acute ischemic stroke secondary to M1 MCA/ICA occlusion in the extended time window

Introduction A validated clinical decision tool predictive of favorable functional outcomes following endovascular thrombectomy (EVT) in acute ischemic stroke (AIS) remains elusive. We performed a retrospective case series of patients at our regional Comprehensive Stroke Center, over a 4-year period, who have undergone EVT to elucidate patient characteristics and factors associated with a favorable functional outcome after EVT. Methods We reviewed all cases of EVT at our institution from 2/2018 - 2/2022 in the extended time window from 6 – 24 hours. Demographic, clinical, imaging, and procedure co-variates were included. A favorable clinical outcome was defined as a modified Rankin scale or 0-2. We included patients with M1 or ICA occlusion treated with EVT within 6-24 hours after symptom onset. We used a univariate and multivariate logistic regression analysis to identify patient factors associated with a favorable clinical outcome at 90 days. Results Our analysis demonstrates that higher recanalization score based on the mTICI scale (2B-3) was a strong indicator of favorable outcome per both our multivariate and univariate analysis (OR 4.11; CI 1.10 – 15.31; p 0.035). Our data also showed signal that the younger age ( p 0.013), lower baseline NIHSS ( p 0.043), shorter hospital length of stay (LOS) ( p 0.030), and absence of pre-existing hypertension ( p 0.026) may also be a predictor of favorable outcome per our univariate analysis. Conclusion Patients without pre-existing hypertension had more favorable outcomes following EVT in the expanded time window. This is consistent with other multicenter data in the expanded time window that demonstrates greater odds of a poor outcome with elevated pre-, peri-, and post-endovascular treatment blood pressure. Our data also demonstrates mTICI score is a strong predictor of favorable outcome even when controlled for other variables. Other factors that may indicate a favorable outcome include younger age, lower baseline NIHSS, and shorter hospital LOS.