Mediation of the Relationship Between Endovascular Therapy and Functional Outcome by Follow-up Infarct Volume in Patients With Acute Ischemic Stroke

Abstract

Endovascular therapy (EVT) substantially reduces disability in patients with acute ischemic stroke with a large vessel occlusion in the anterior circulation.^1-7 It is assumed that this positive treatment effect is caused by the salvage and preservation of brain tissue. This idea is strengthened by many studies that have shown a strong relationship between the extent of ischemic tissue injury assessed at follow-up imaging and functional outcome.^8-12 With this in mind, follow-up infarct volume (FIV) has been suggested as an early measure of treatment efficacy because this represents a potentially more objective estimate of the pathological response to treatment than functional outcome. However, the validity of a potential surrogate outcome measure depends on the demonstration that the effects of therapy on that surrogate accurately reflects and reliably predicts the effects of therapy on the clinical end point.¹³ Formal testing through a mediation analysis is relevant to establishing the full potential of FIV as an early measure of treatment efficacy.