Incidence and predictors of poor functional outcome despite complete recanalisation following endovascular thrombectomy for acute ischaemic stroke.

Background: Numerous ischaemic stroke patients experience poor functional outcome despite successful recanalisation following endovascular thrombectomy (EVT). We aimed to identify the incidence and predictors of futile complete recanalisation (FCR) in a national stroke registry.

Methods: Patients who achieved complete recanalisation (mTICI 3) following EVT, between October 2015 and March 2020, were included from a United Kingdom national stroke registry. Modified Rankin Scale of 4-6 at discharge was defined as a 'poor/futile outcome'. Backward stepwise multivariable logistic regression analysis was performed with FCR as the dependent variable, incorporating all baseline characteristics, procedural time metrics and post-procedural events.

Results: We included 2132 of 4383 patients (48.8%) with complete recanalisation post-EVT, of which 948 patients (44.4%) developed FCR. Following multivariable regression analysis adjusted for potential confounders, patients with FCR were associated with multiple baseline patient, imaging and procedural factors: age (p=0.0001), admission NIHSS scores (p=0.0001), pre-stroke disability (p=0.007), onset-to-puncture (p=0.0001) and procedural times (p=0.0001), presence of diabetes (p=0.005), and use of general anaesthesia (p=0.0001). Although not predictive of outcome, post-procedural events including development of any intracranial haemorrhage (ICH) (p=0.0001), symptomatic ICH (sICH) (p=0.0001) and early neurological deterioration (END) (p=0.007) were associated with FCR.

Conclusion: Nearly half of patients in this national registry experienced FCR following EVT. Significant predictors of FCR included increasing age, admission NIHSS scores, pre-stroke disability, onset-to-puncture and procedural times, presence of diabetes, atrial fibrillation, and use of general anaesthesia. Post procedural development of any ICH, sICH, and END were associated with FCR.