Course of carotid artery occlusions with impaired cerebrovascular reactivity.

BACKGROUND AND PURPOSE Retrospective studies have found a close correlation between an impaired cerebrovascular reserve capacity and the incidence of hemodynamic stroke. The present study evaluates this relation prospectively. METHODS We measured the CO2 reactivity in 85 patients with internal carotid artery occlusions by transcranial Doppler sonography (Doppler CO2 test). All patients were prospectively followed for 38 +/- 15 (mean +/- SD) months. RESULTS In the group with sufficient CO2 reactivity, four of 48 (8%) developed ipsilateral transient symptoms, none a stroke. In cases with diminished or exhausted cerebrovascular reserve capacity, 12 of 37 (32%) suffered an ipsilateral event (four transient ischemic attacks, eight strokes) (p less than 0.01). CONCLUSIONS The Doppler CO2 test seems to be a valuable method of estimating the risk of stroke in patients with carotid artery occlusions.