Abstract TP142: Prevalence of Cerebral Ischemic Events in Extraluminal Protruding Intracranial Atherosclerotic Plaques: Analysis of Intracranial Vessels from the Nun Study

Abstract

INTRODUCTION: The prevalence and clinical significance of extraluminal protruding plaques in intracranial arteries is not fully understood. We aimed to identify the prevalence of ischemic events in persons with extraluminal protruding plaques in intracranial arteries. METHODS: A random sample of 100 subjects from Nun Study repository of post-mortem intracranial arteries was inspected. The study is a longitudinal study of aging and Alzheimer’s disease funded by the National Institute on Aging including 678 participants. A total of 61 subjects with visible atherosclerotic changes (defined as change in vessel wall color) were selected. The specimens were placed in a liquid container and an angiographic catheter was placed in vessel of interest. Angiography was obtained in multiple planes. Percentage luminal stenosis was measured using proximal or distal normal vessel as reference. Using microscopic images, extraluminal protruding plaques was then sequentially measured. RESULTS: Out of 61 subjects, 41 (67%) had angiographically detectable atherosclerotic plaques. Thirteen (13%) subjects had extraluminal protruding plaques and the remaining 7 (20%) subjects have neither angiographic stenosis nor extraluminal protruding plaques. Mean life expectancy was higher in patients with angiographic stenosis and outside plaque protrusion (59 and 51 versus 47 years). The prevalence of lacunar infarct, large infarct (>1.5cm) in autopsy, and infarction identified in patient’s brain MRI were all higher in patients with extraluminal protruding plaques than patients without any plaque (38% versus 29%, 37% versus 31%, and 15% versus 14%, respectively). Mean serum cholesterol level was higher in patients with extraluminal protruding plaques (264 mg/dl versus 205 mg/dl). The prevalence of dementia in patients with angiographic stenosis, extraluminal protruding plaques, and no wall thickness change was 80%, 20%, and zero, respectively. CONCLUSIONS: Extraluminal protruding plaques without angiographic stenosis appear to be associated with ischemic events in patients. Higher prevalence of ischemic events in these patients warrants early detection using high resolution MRIand possible intervention.