Factors associated with poor functional outcome in endovascular thrombectomy – a systematic review and meta-analysis

Background: The role of endovascular thrombectomy (EVT) in the treatment of acute ischaemic stroke caused by anterior circulation, large vessel occlusion is now well established. Determining factors predictive of poor outcome may refine selection criteria and further improve results. Aims: To identify factors associated with poor functional outcome (mRS 5-6) following EVT. Methods: A systematic literature search was performed and randomised control trials (RCTs) of EVT were selected. Details of the protocol for this systematic review were registered on PROSPERO and available at www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42018087590. Trial level data were manually extracted and univariate logistic regression analyses performed. Results: Ten RCTs met the inclusion criteria (n = 1125 EVT patients). Longer time to: randomisation(OR 1.002, 95%CI 1.000–1.004;p = 0.01); groin puncture(OR 1.002, 95%CI 1.001–1.004;p < 0.01); and reperfusion (OR 1.002,95%CI 1.001–1.003;p < 0.01); and increased procedure time (OR 1.020, 95%CI 1.004–1.036;p = 0.01) were associated with significantly increased odds of poor functional outcome, as was poor partial reperfusion (TICI 2a;OR 1.064, 95%CI 1.034–1.094;p < 0.01). In contrast, higher rates of: complete reperfusion (TICI 3;OR 0.975, 95%CI 0.959–0.992; p < 0.01); middle cerebral artery second segment (M2) occlusions (OR 0.892, 95%CI 0.815–0.976; p = 0.01); and administration of IV-tPA(OR 0.986, 95% CI 0.978–0.994; p < 0.01) demonstrated evidence for decreased odds of poor functional outcome. Conclusion: Delayed time to: presentation, starting EVT and achieving reperfusion as well as increased procedure time, may predict poor outcomes in EVT. Distal occlusions, administration of IV-tPA and complete final reperfusion may be protective.