Abstract WP97: Routine MRI Reveals Prior Stroke In The Same Vascular Territory In Half Of Patients Presenting With Acute Ischemic Stroke Due To Intracranial Atherosclerotic Disease

Abstract

Introduction: In 2012, after SAMMPRIS demonstrated worse 30-day outcomes with Wingspan intracranial stent placement for intracranial atherosclerotic disease (ICAD), the FDA narrowed the “on-label” indication to a very specific subset of patients with symptomatic ICAD. The updated criteria require a prior stroke in the territory of the symptomatic vessel based on clinical history. Limitations in the accuracy of diagnosis of clinical stroke may be overcome with the use of MRI to identify any prior stroke - whether clinical or subclinical - which could expand the number of patients who are eligible for stenting. Methods: This was a retrospective analysis of consecutive cases of acute ischemic stroke attributable to ICAD with 50-99% stenosis in the symptomatic vessel from July 2019 - June 2022. MRI FLAIR sequences were reviewed for imaging evidence of prior infarction in the vascular territory of the symptomatic vessel. Subgroup analysis was performed based on stroke location, infarct pattern, degree of stenosis, and premorbid medication use. Results: 73 patients met inclusion criteria. Mean age was 72, and 41% were women. 37 patients (51%) exhibited MRI evidence of prior stroke in the same vascular territory. Of these, only 18/37 (49%) reported a prior clinical stroke. The frequency of prior stroke on MRI was similar with anterior (51%) and posterior (50%) circulation ICAD. Frequency of prior stroke based on infarct pattern was 64% for border zone infarction, 42% for thromboembolism, and 55% for branch atheromatous disease. Of the 31 patients who had degree of stenosis quantified on DSA, the frequency of prior infarction was 63% in patients with 70-99% stenosis versus 48% in those with <70% stenosis. Only 1 patient (1.4%) met FDA on-label criteria for intracranial stenting. The most common reason for ineligibility was absent history of clinical stroke in the territory of the symptomatic vessel (75%). Conclusions: In patients presenting with acute stroke due to symptomatic ICAD, half exhibit MRI evidence of a prior stroke in the symptomatic arterial territory, and half of these prior strokes are not reported from clinical history. Routine MRI can be a valuable tool to identify prior stroke in the symptomatic territory, which may in turn expand therapeutic options for ICAD.