A substantial proportion of acute stroke patients fail to recover following successful endovascular therapy (EVT) and injury to the brain and vasculature secondary to reperfusion may be a contributor. Acute stroke patients were included with: i) large vessel occlusion of the anterior circulation, ii) successful recanalization, and iii) evaluable MRI early after EVT. Presence of hyperemia on MRI perfusion was assessed by consensus using a modified ASPECTS. Three different approaches were used to quantify relative cerebral blood flow (rCBF). Sixty-seven patients with median age of 66 [59–76], 57% female, met inclusion criteria. Hyperemia was present in 35/67 (52%) patients early post-EVT, in 32/65 (49%) patients at 24 hours, and in 19/48 (40%) patients at 5 days. There were no differences in incomplete reperfusion, HT, PH-2, HARM, severe HARM or symptomatic ICH rates between those with and without early post-EVT hyperemia. A strong association (R2 = 0.81, p < 0.001) was found between early post-EVT hyperemia (p = 0.027) and DWI volume at 24 hours after adjusting for DWI volume at 2 hours (p < 0.001) and incomplete reperfusion at 24 hours (p = 0.001). Early hyperemia is a potential marker for cerebrovascular injury and may help select patients for adjunctive therapy to prevent edema, reperfusion injury, and lesion growth.

Introduction: A substantial proportion of acute stroke patients experience poor outcomes following successful endovascular therapy (EVT) and reperfusion injury to the brain and vasculature may be a contributor. The purpose of this pilot study was to characterize hyperemia following recanalization and test the association of hyperemia with evolution of the ischemic lesion. Methods: Acute stroke patients were included with: i) large vessel occlusion of the anterior circulation, ii) successful recanalization, and iii) evaluable MRI early after EVT. Presence of hyperemia on MRI perfusion was assessed by consensus using a modified ASPECTS. Three different approaches were used to quantify relative cerebral blood flow (rCBF) on early post-EVT, 24 hours, and 5 days. Two independent trained readers measured lesion volumes using a semi-automated validated approach. Results: Sixty-seven patients with median age of 66 [59-76], 57% female, met inclusion criteria. Hyperemia was present in 35/67 (52%) patients early post-EVT (Figure), in 32/65 (49%) patients at 24 hours, and in 19/48 (40%) patients at 5 days. In comparison to control regions, rCBF was elevated by greater than 50% in hyperemic regions. Patients with hyperemia had larger ischemic lesion volumes and early lesion growth. A strong association (R2=0.81, p<0.001) was found between early post-EVT hyperemia (p=0.027) and lesion growth based on DWI volume at 24 hours, after adjusting for DWI volume at 2 hours (p<0.001) and incomplete reperfusion at 24 hours (p=0.001). Conclusions: Hyperemia is frequently observed after successful EVT and is associated with lesion growth at 24 hours. Evidence of hyperemia may identify patients that may benefit from adjunctive therapy to prevent reperfusion injury, edema, and lesion growth.