Stroke risk in the early period after carotid related symptoms: a systematic review

Current guidelines recommend performing carotid endarterectomy in patients with symptomatic carotid disease as soon as possible after the neurological index event. However, early stroke risk has not been well documented for this patient group. We therefore conducted a systematic analysis of the current literature on the recurrent risk of ischemic events in patients with symptomatic carotid stenosis. Systematic review was performed by searching the MEDLINE® database from 1950 until June 8, 2015 (key words: cerebral ischemia, transient ischemic attack, amaurosis fugax, stroke, symptomatic carotid stenosis, recurrent risk, outcome, prognosis, follow-up, cohort and natural history). All studies reporting stroke risks in patients with symptomatic carotid stenosis after neurologic index events within a period of 7 days were included. Cumulative stroke risks with 95% confidence intervals after a neurologic index event were recalculated at 2-3, 7, 14 and 30 days and a meta-analysis including an analysis of heterogeneity were performed using the statistical package R and Excel for Mac 2003. Ten studies with a total number of 2634 patients were included. Results of an overall stroke risk were as follows: 2.0-17.2% at 2-3 days, 0-22.1% at 7 days, 0-29.6% at 14 days and 0-11.1% at 30 days in patients with a symptomatic extracranial carotid stenosis. The pooled stroke risk in the six studies with active follow-up was 6.0% (95% CI 2.4-14.4) at 2-3 days, 10.9% (6.1-18.7) at 7 days and 17.6% (9.7-29.9) at 14 days. Pooled stroke risk in the three studies with uncensored populations was even higher with 6.4% (1.5-23.8%) at 2-3 days, 19.5% (12.7-28.7) at 7 days and 26.1% (20.6-32.5%) at 14 days. Significant heterogeneity (P<0.001) could be explained by the different inclusion criteria and the study's design. Retrospective studies with passive follow-up had the lowest stroke risk whereas prospective studies with active follow-up and without bias through early intervention by carotid endarterectomy or carotid stenting had the highest stroke risk. The risk of recurrence of cerebrovascular events in patients with symptomatic carotid stenosis within the first days after a neurologic index event is as high as 6.4% (1.5-23.8), 19.5% (12.7-28.7) and 26.1% (20.6-32.5) after 2-3, 7 and 14 days respectively. Patients with a symptomatic carotid stenosis are therefore at a very high risk of a definitive stroke. Recommendations by current guidelines to perform carotid endarterectomy as soon as possible after the neurologic index event are therefore justified.