Cerebrovascular Reactivity to Acetazolamide and Outcome in Patients With Symptomatic Internal Carotid or Middle Cerebral Artery Occlusion: A Xenon-133 Single-Photon Emission Computed Tomography Study

Background and Purpose— The present study prospectively evaluated relationships among baseline characteristics, cerebral hemodynamics, and outcome of patients with symptomatic major cerebral artery occlusion, by quantitative measurement of cerebral blood flow using xenon-133 (133Xe) inhalation and single-photon emission computed tomography (SPECT). Methods— Regional cerebrovascular reactivity (rCVR) to acetazolamide was calculated at entry to the study using 133Xe SPECT. Seventy consecutive patients aged less than 70 years with unilateral internal carotid artery (ICA) or middle cerebral artery (MCA) occlusion were divided into 2 groups: normal or reduced rCVR, and prospectively followed up for a period of 24 months. Results— During the follow-up period, recurrent strokes occurred in 8 of the 23 patients with reduced rCVR at entry and in 3 of 47 patients with normal rCVR. Cumulative recurrence-free survival rates in all patients, and in each subgroup of patients with ICA or MCA occlusion and reduced rCVR on entry, were significantly lower than in those with normal rCVR (P =0.0030, P =0.0404, and P =0.0310, respectively; Kaplan-Meier analysis). Among the factors considered, only lower rCVR and resting regional cerebral blood flow values were significantly associated with the risk of stroke recurrence (P =0.0019 and P =0.0080, respectively; Cox regression multivariate analysis). Conclusions— The present study demonstrated that reduced rCVR to acetazolamide as determined by 133Xe SPECT is significantly associated with an increased risk of stroke recurrence in patients with symptomatic MCA or ICA occlusion.