Risk of Stroke in Relation to Degree of Asymptomatic Carotid Stenosis: A Population-based Cohort Study, Systemic Review, and Meta-analysis

Abstract

Prospective, population-based study (Oxford Vascular Study) between April 1, 2002, and April 1, 2017, and a systematic review using MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials between January 1, 1980, and October 1, 2020. In the population-based study, patients with 70% to 99% asymptomatic stenosis had a significantly greater 5-year ipsilateral stroke risk (15% [6/53]) than those with 50% to 69% stenosis (0% [0/154]), as did patients with 80% to 99% asymptomatic stenosis (18% [6/34]) compared with those with 50% to 79% stenosis (1.0% [2/173]). In the systemic review, the ipsilateral stroke risk in asymptomatic patients was significantly higher in patients with 70% to 99% stenosis (10% [386/3778]) than in patients with 50% to 69% stenosis (5% [181/3,806 patients]), and in patients with 80% to 99% stenosis (11% [77/727]) compared with those with 50% to 79% stenosis (5% [167/3272]). The stroke risk reported in cohort studies was highly dependent on the degree of asymptomatic carotid stenosis, suggesting that the benefit of carotid endarterectomy (CEA) might be underestimated in patients with severe stenosis. Conversely, the 5-year stroke risk was low for patients with moderate stenosis with contemporary medical treatment, calling into question any benefit from revascularization for patients with less than 70% to 80% stenosis.