Cerebrovascular reactivity predicts stroke in high-grade carotid artery disease

OBJECTIVE:To assess the usefulness of transcranial Doppler CO2 reactivity (CO2R) for prediction of ipsilateral ischemic stroke in carotid artery stenosis and occlusion with a meta-analysis of prospective studies based on individual patient data. METHODS:We searched Medline, Biosis Previews, Science Citation Index, The Cochrane Library, and EMBASE for studies in which patients with severe carotid artery stenosis or occlusion underwent Doppler CO2R testing (inhalation of CO2 or breath-holding) and were prospectively followed for ipsilateral ischemic stroke. Individual data from 754 patients from 9 studies were included. We used percentage cerebral blood flow velocity increase (pCi) during hypercapnia as the primary CO2R measure, and defined impaired reactivity as pCi