Risk of Recurrent Stroke in Patients with Symptomatic Mild (20-49% NASCET) Carotid Artery Stenosis

The objective of this study was to evaluate the risk of recurrent ischaemic stroke in patients with ultrasound assessed symptomatic mild carotid artery stenosis (20-49% NASCET) treated solely with modern medical treatment.

This was a retrospective, observational register cohort study. Three groups of patients were recruited from a database of all carotid Doppler ultrasound examinations performed in the Gothenburg region between 2004 and 2009. Patients with symptomatic mild carotid artery stenosis (n = 162) were compared with patients with asymptomatic carotid artery stenosis (n = 301) of equal degree and a group of patients with surgically (CEA) treated symptomatic moderate or severe carotid artery stenosis (n = 220). Kaplan-Meier estimates and Cox proportional hazard models were used to compare the primary outcome (ipsilateral ischaemic stroke) between groups.

After a 3 year follow up, the cumulative incidence of recurrent ipsilateral stroke in patients with symptomatic mild carotid artery stenosis was 7.4%. Patients with symptomatic mild carotid artery stenosis had a substantially increased risk of recurrent ipsilateral stroke compared with asymptomatic patients with equal degree of stenosis (HR 5.5. 95% CI 1.8-17.1; p = .003) as also compared with patients with CEA treated symptomatic moderate or severe stenosis (HR 7.8. 95% CI 1.62-37.8; p = .011).

The present study on patients with symptomatic mild carotid artery stenosis, as determined by Doppler ultrasound, shows that there is still a substantial risk of recurrent stroke in this group.