The present study was aimed to clarify if cerebrovascular reactivity to acetazolamide can be a reliable predictor for fuether ischemic stroke in medically treated patients with internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion. Ninety-one 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 and reactivity to acetazolamide were determined by single photon emission computed tomography (SPECT). All patients were medically treated. Follow-up study during mean 42.9 months revealed that annual risks of ipsilateral and total stroke were significantly higher in the patients with reduced blood flow and reactivity risk than others (Kaplan-Meier method and Mantel-Cox log-rank statistics). Annual risk of ipsilateral stroke was 21.8% in these patients, whereas it ranged from 0.5 to 2.4% in others. Annual risk of total stroke was 32.7% in these patients, whereas it ranged from 2.4 to 4.8% in others. The present results strongly suggest that reduced blood flow and reactivity to acetazolamide is predictive for subsequent ischemic stroke in patients with ICA or MCA occlusion.
