Cerebral hemodynamic benefits after carotid artery stenting in patients with near occlusion

Objective The natural history and management of patients with near occlusion (NO) of the internal carotid artery are controversial. In particular, it is unclear whether cerebral hemodynamics are compromised in these patients and whether improvement by carotid revascularization leads to the prevention of ischemic stroke. In this study, we measured cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) using single-photon emission computed tomography before and after carotid artery stenting (CAS) for NO to examine the effectiveness of CAS from the perspective of cerebral hemodynamics. Methods CAS was performed in 15 patients with NO and in 78 with severe stenosis (≥70%) but without NO at our institution. Resting CBF and CVR to acetazolamide were measured using N -isopropyl-p-[I-123] iodoamphetamine single-photon emission computed tomography before and at 3 to 6 months after CAS. We also measured CBF using the same method for healthy individuals and compared the results among the three groups. Results CAS was successfully performed in all patients. Before CAS, the mean resting CBF was 26.68 ± 4.23 mL/100 g/min, and the mean CVR was −0.8% ± 15.1% in the patients with NO, both of which were significantly lower than in patients with severe stenosis without NO and in healthy individuals. After CAS, the mean resting CBF and mean CVR in patients with NO increased significantly to 30.07 ± 5.67 mL/100 g/min and 37.0% ± 21.4%, respectively, and there were no significant differences among the three groups. Conclusions Before CAS, patients with NO were more hemodynamically compromised than those with severe stenosis without NO. After CAS, significant cerebral hemodynamic improvement and normalization occurred long-term. Thus, from a hemodynamic perspective, CAS was effective in patients with NO.