Factors that may contribute to poor outcome despite good reperfusion after acute endovascular stroke therapy

Endovascular therapy with mechanical thrombectomy is a formidable treatment for severe acute ischemic stroke caused by occlusion of a proximal intracranial artery. Its strong beneficial effect is explained by the high rates of very good and excellent reperfusion achieved with current endovascular techniques. However, there is a sizable proportion of patients who do not experience clinical improvement despite successful recanalization of the occluded artery and reperfusion of the ischemic territory. Factors such as baseline reserve, collateral flow, anesthesia and systemic factors have been identified as potential culprits for lack of improvement in the setting of timely and successful revascularization. Older age, baseline disability and perhaps radiological markers of chronic brain injury can affect the prognosis of patients treated with endovascular therapy. Collateral flow is a major determinant of outcome after endovascular therapy and it is manifested by the size of the core in relation to the volume of the salvageable tissue. Parenchymal and vascular imaging can help assess the quality of collateral flow, but the optimal radiological strategy for daily practice (i.e. the optimal combination of rapid availability and diagnostic precision) has not been established. A sizable body of observational evidence indicates that acute hypertension, hyperglycemia and fever are associated with worse outcomes after a stroke even after optimal reperfusion with endovascular therapy. Lastly, current randomized controlled trials in anesthesia for stroke demonstrate similar rates of good functional outcome between general anesthesia and conscious sedation suggesting equipoise exists.