Changes in Cerebral Vascular Reserve Capacity after Carotid Artery Stenting: A 6-Month Follow-up Study

ABSTRACT

BACKGROUND: Assessment of cerebral vascular reserve capacity prior to carotid artery stenting is used for predicting hyperperfusion syndrome. However, the changes in vascular reserve capacity after carotid stenting are not fully understood. In this study we investigated the effects of carotid artery stenting on the restoration of vascular reserve capacity using (99m)TC-hexamethylpropylene amine oxime (HMPAO) single-photon-emission computed tomography (SPECT). METHODS: The study population comprised 29 patients who underwent carotid artery stenting. Patients were divided into groups according to occlusion of the contralateral internal carotid artery (unilateral group vs bilateral group) and according to the presence or absence of symptoms related to carotid stenosis (symptomatic group vs asymptomatic group). Pre- and postacetazolamide-activated (99m)TC-HMPAO SPECT were performed prior to stent insertion and at 1 and 6 months postoperatively. Vascular reserve capacity was assessed based on pre-, and 1- and 6-month postacetazolamide gamma count ratio (Post0, Post1, and Post6, respectively) and cerebrovascular reactivity (CVR0, CRV1, and CRV6, respectively). RESULTS: The postacetazolamide gamma count ratio and cerebrovascular reactivity tended to improve at 1 month after stenting, but tended to deteriorate at 6 months after stenting in the unilateral group compared with the bilateral group [Post0-Post1=0.045+/-0.078 (mean+/-SD), p=0.014; Post0-Post6=0.025+/-0.063, p=0.042; Post1-Post6=-0.020+/-0.047, p=0.102; CVR0-CVR1=0.043+/-0.071, p=0.008, CVR0-CVR6=0.019+/-0.063, p=0.097; CVR1-CVR6=-0.024+/-0.047, p=0.008] and in the symptomatic group compared with the asymptomatic group (Post0-Post1=0.058+/-0.106, p=0.038; Post0-Post6=0.048+/-0.103, p=0.061; Post1-Post6=-0.010+/-0.048, p=0.700; CVR0-CVR1=0.037+/-0.083, p=0.074; CVR0-CVR6=0.014+/-0.073, p=0.344; CVR1-CVR6=-0.023+/-0.054, p=0.055). CONCLUSIONS: The observed increases in postacetazolamide gamma count ratio and cerebrovascular reactivity at 1 month followed by decreases at 6 months may reflect the restoration of vascular reserve capacity. Carotid artery stenting can improve vascular reserve capacity, especially in patients with unilateral stenosis and with symptomatic stenosis.