Relationship between magnetic resonance angiography-diffusion-weighted imaging mismatch and clinical outcome in endovascular treatment for acute ischemic stroke: subgroup analysis of the Recovery by Endovascular Salvage for Cerebral Ultra-acute Embolism--Japan Registry.

BACKGROUND: The presence or absence of the penumbra area is important when performing reperfusion therapy in patients with acute ischemic stroke. As a predictor of this penumbra area, magnetic resonance angiography (MRA)-diffusion-weighted imaging (DWI) mismatch is attracting attention. The usefulness of MRA-DWI mismatch (MDM) using the DWI-Alberta Stroke Program Early Computed Tomography Score (ASPECTS) in endovascular treatment (EVT) of patients with cerebral large vessel occlusion was evaluated.

METHODS: Of 1442 patients registered in the Recovery by Endovascular Salvage for Cerebral Ultra-acute Embolism-Japan Registry between July 1, 2010 and June 30, 2011 who presented to the hospital within 24 hours of the onset of acute cerebral infarction because of cerebral large vessel occlusion, 188 patients who had internal carotid artery or middle cerebral artery occlusion and achieved recanalization with EVT were included. Of these, 71 patients underwent intracranial EVT because intravenous recombinant tissue plasminogen activator therapy was ineffective. The associations between the presence or absence of MDM (MDM-positive [MDM-P], DWI-ASPECTS≥6; MDM-negative [MDM-N], DWI-ASPECTS<6) and 90-day prognosis (modified Rankin Scale [mRS]) and symptomatic intracranial hemorrhage (sICH) were examined.

RESULTS: Of the 188 patients analyzed, the time from symptom onset to admission was within 3 hours in 143 patients, 3-8 hours in 36 patients, and 8 hours or more in 9 patients. The time from the onset was within 3 hours in 118 patients in the MDM-P and 25 patients in the MDM-N cases. Favorable outcomes (mRS score≤2 at 90 days) were seen in 63 patients (53.4%) in the MDM-P group and 7 patients (28.0%) in the MDM-N group, showing a significantly more favorable clinical outcome in the MDM-P group (P=.027). The incidence of sICH was significantly lower in the MDM-P group (MDM-P group 3.4%, MDM-P group 20.0%; P=.009). The time from the onset was 3-8 hours in 29 patients in the MDM-P group and in 7 patients in the MDM-N group. Favorable outcomes were seen in 12 patients (41.4%) in the MDM-P group and 2 patients (28.6%) in the MDM-N group, with no significant difference between the 2 groups. No patients had sICH. The patients admitted 8 hours or more after the onset were all MDM-P. Five patients (55.6%) had a favorable outcome.

CONCLUSIONS: This study demonstrated the safety and efficacy of EVT in MDM-P patients within 3 hours of symptom onset. Although the ratio of patients who had a favorable outcome was high in the MDM-P patients admitted 3-8 hours after the onset, the difference was not significant.