Abstract 97: Association between Non-Stenosing Carotid Artery Plaque and Acute Ischemic Stroke

Abstract

Introduction: It is unknown whether stroke risk is increased in the setting of large-artery atherosclerotic plaque that does not cause significant luminal stenosis. Hypothesis: We hypothesized that the prevalence of vulnerable, non-stenosing carotid artery plaque on the side ipsilateral to an acute brain infarction would be higher than on the contralateral side. Methods: Using a prospective stroke registry, we identified patients with acute infarction limited to the vascular territory of one internal carotid artery (ICA) and no large-vessel atherosclerosis based on the common criterion of greater than or equal to 50% luminal stenosis. We used magnetic resonance angiography to ascertain vulnerable ICA plaque, as defined by the presence of intraplaque high-intensity signal (IHIS). We used McNemar’s test for correlated proportions to compare the prevalence of IHIS on the side ipsilateral to acute infarction versus the contralateral side within individual subjects. Results: We analyzed 218 arteries in 109 unique patients. IHIS-positive ICA plaque was found in 31 arteries (14.2%), with 22 IHIS-positive lesions occurring ipsilateral to the side of the patient’s infarction versus 9 IHIS-positive lesions contralateral to the side of infarction (P = 0.01). When stratified by stroke subtype (See Figure which includes representative MRA images), IHIS was associated with infarctions that were classified as of unknown etiology (P < 0.001), but not in those due to cardioembolism (P = 0.76) or small-vessel occlusion (P = 0.49). Conclusion: We found an association between vulnerable, non-hemodynamically-significant ICA plaque and acute brain infarction. This association held true only in the subset of patients with stroke of undetermined etiology, suggesting that non-stenosing large-artery atherosclerotic lesions may explain some proportion of cryptogenic strokes.