The Natural History and Stroke Risk of Carotid Artery Occlusion

Limited available data suggests the incidence of carotid artery occlusion (CAO) is declining, and if detected, the association with acute stroke is very low. We report our long-term stroke outcomes in patients with CAO in an integrated health system. We identified adult patients with evidence of CAO at initial imaging from 2008 to 2012 or identified during follow-up through 2017 without prior carotid intervention. The primary outcome was acute ischemic stroke (AIS) attributed to the carotid artery (any ipsilateral stroke within the anterior circulation, including internal capsule, basal ganglia, and thalamus). Timing of stroke was assessed in three intervals: >6 months prior to CAO imaging, within 6 months of CAO including the time of imaging study acquisition, and in follow-up until study endpoint. Secondary outcomes include ischemic stroke of other etiology and/or location, and survival. Among over 94,800 eligible patients with carotid imaging, 2084 arteries in 2044 patients were identified with CAO, including 1787 arteries (85.8%) occluded at baseline and 297 arteries (14.3%) that occluded in follow-up. The mean age was 71 ± 11 years, and 35.6% of patients were female. The mean maximal follow-up was 4.8 ± 3.1 years. Of patients that occluded in follow-up, 37, 60, and 189 CAO were seen with baseline arteries with mild/none, moderate, and severe stenosis, respectively. The mean time of progression to occlusion (without interceding intervention) was 3.2 ± 2.2 years for arteries with no/mild stenosis, 3.5 ± 2.4 years for arteries with moderate stenosis, and 1.5 ± 2.0 years for arteries with severe stenosis. In total, 366 ipsilateral AIS events (17.6%) occurred in 346 arteries, with 297 strokes in arteries occluded at baseline and 69 in arteries that occluded in follow-up. The majority of carotid-related strokes (79.2%) occurred within 6 months prior to CAO (Table). After ipsilateral AIS, 5 patients (11.6%) died within 30 days, an additional 8 patients (18.6%) within 1 year, and 16 patients (37.2%) were alive at the end of follow-up. The overall mortality rate was 43.5%, with 13.9% of patients lost to follow-up. There were 370 other strokes (17.8%) observed in 350 arteries, including 308 contralateral strokes in 288 arteries and 62 ipsilateral strokes not attributable to carotid disease. The observed incidence of CAO is low in this select cohort of patients; however, the incidence of carotid-related stroke and associated short- and long-term mortality is high. Further investigation is needed to identify patients at risk of progression to CAO to prevent the associated morbidity and mortality of stroke.TableCharacteristics of occlusion and stroke outcomes by initial artery statusTotalN = 2084, No. (%)Occlusion at baseline n = 1787, No. (%)Occluded during follow-up n = 297, No. (%)Ipsilateral carotid-related stroke366 (17.6)297 (16.6)69 (23.2) >6 months prior to occlusiona30 (8.2)20 (6.7)10 (14.5) ≤6 months prior to occlusiona290 (79.2)243 (81.8)47 (68.1)In follow-up (after occlusion)a46 (12.6)34 (11.4)12 (17.4)aPercentages derived from the total number of ipsilateral carotid-related strokes in each column. Open table in a new tab