Is impaired cerebral vasomotor reactivity a predictive factor of stroke in asymptomatic patients?

Background and Purpose Identification of the subgroup of asymptomatic patients with severe internal carotid artery stenosis and high risk of stroke has important clinical implications. Cerebral vasomotor reactivity provides information regarding intracranial hemodynamic features and might have a prognostic value in predicting cerebrovascular ischemic events, especially in patients with carotid stenosis. The aim of our study was to assess the cerebral vasomotor reactivity in asymptomatic patients with carotid stenosis and evaluate its role in stroke occurrence. Methods Cerebral vasomotor reactivity was assessed using transcranial Doppler ultrasonology and the Diamox test (intravenous administration of 1.0 g acetazolamide) in 44 asymptomatic patients with severe (>70%) internal carotid artery stenosis. Patients were followed up prospectively (mean, 2 years). Results Cerebral vasomotor reactivity was estimated as good (>40% increase of blood flow velocity in the middle cerebral artery ipsilateral to the carotid stenosis after undergoing the Diamox test) in 23 patients; it was impaired in the other 21. During the follow-up period, the overall annual rate for ipsilateral stokes was 2.3%; it was 7.9% for all ischemic cerebral events. No strokes or transient ischemic attacks occurred in the former group, but there were 7 cerebral ischemic events (2 strokes [1 fatal] and 5 transient ischemic attacks) in the latter group. There was a statistically significant correlation between cerebral ischemic events and impaired cerebral vasomotor reactivity (P=.009). Conclusions The data of this preliminary study suggest an important role of impaired cerebral vasomotor reactivity in predicting ischemic cerebral events. Preventive vascular surgery might be considered in this high-risk subgroup of asymptomatic patients with severe carotid stenosis.