Long-term prognosis of medically treated patients with internal carotid or middle cerebral artery occlusion - Can acetazolamide test predict it?

Background and Purpose-The importance of hemodynamic parameters for predicting outcome in patients with occlusive carotid disease remains controversial. The present study was aimed at testing the hypothesis that regional cerebrovascular reactivity (rCVR) to acetazolamide can be a reliable predictor of subsequent ischemic stroke in medically treated patients with internal carotid artery or middle cerebral artery occlusion. Methods-Seventy-seven symptomatic patients were enrolled in this prospective, longitudinal cohort study. All patients met inclusion criteria of cerebral angiography, no or localized cerebral infarction on MRI or CT, and no or minimal neurological deficit. Regional cerebral blood flow (rCBF) and rCVR to acetazolamide were quantitatively determined by Xe-133 SEPCT. All patients were categorized into 4 types on the basis of SPECT studies. Results-During an average follow-up period of 42.7 months, 16 total and 7 ipsilateral ischemic strokes occurred. The annual risks of total and ipsilateral stroke in patients with decreased rCBF and rCVR were 35.6% and 23.7%, respectively, risks that are higher than those in other types of patients. When strokes were categorized into patients with and without decreased rCBF and rCVR, Kaplan-Meier analysis revealed that the risks of total and ipsilateral stroke in patients with decreased rCBF and rCVR were significantly higher than in those without (P < 0.0001 and P = 0.0001, respectively, log-rank test). Relative risk conferred by decreased rCBF and rCVR was 8.0 (95% Cl, 1.9 to 34.4) for ipsilateral stroke and 3.6 (95% CI, 1.4 to 9.3) for total stroke. Conclusions-Decreased rCBF and rCVR to acetazolamide may identify a subgroup of patients who have a higher risk of subsequent ischemic stroke when treated medically.