Background Analyzing risk factors for hyperperfusion-induced intracranial hemorrhage (HICH) after carotid artery stenting (CAS) in patients with symptomatic severe carotid stenosis.

Methods This study retrospectively analyzed clinical data of 210 patients, who had symptomatic severe carotid stenosis (70–99%) and received CAS treatment between June 2009 and June 2015, and evaluated the relationship of HICH with patients’ clinical baseline data, imaging features, and treatment strategies.

Results Seven patients (3.3%) developed HICH after CAS. The incidence of HICH among patients with near total occlusion was significantly higher than among those without (10.1% vs 0%, P<0.001). Out of the seven, five had no development of either anterior or posterior circulations, and two had no development of anterior circulation and poor development of posterior circulation. Results showed that patients with poor compensation of Willis’ Circle were more likely to develop HICH compared with other patients (P<0.001). All patients received preoperative CT perfusion. TTP index was defined as the TTP ratio between the affected and contralateral side. The results showed that the TTP index was significantly different between the HICH group and non-HICH group (1.15±0.10 vs 1.30±0.15, P<0.001). An analysis of the ROC curve indicated that patients with TTP index >1.22 were more likely to develop HICH compared with other patients (sensitivity 100%, specificity 75.9%).

Conclusions Patients with severe unilateral carotid stenosis, the presence of near total occlusion, poor compensation of Willis’ Circle, and preoperative TTP index>1.22, have a higher risk of developing HICH after CAS.