Incidence of moderate to severe cognitive dysfunction in patients treated with carotid artery stenting

Abstract

Objective: Approximately 25% of patients with carotid artery stenosis treated with carotid endarterectomy develop cognitive dysfunction (CD) between 1 day and 1 month after surgery compared with a control group. We hypothesized that patients with carotid artery stenosis treated with carotid artery stenting (CAS) performed under cerebral embolic protection also develop CD at similar time points compared with a control group.

Methods: Twenty-four patients scheduled for elective CAS were enrolled in a prospective institutional review board-approved study to evaluate cognitive function with a battery of 6 neuropsychometric tests before, and 1 day and 1 month after, CAS. Test performance was compared with 23 patients undergoing coronary artery procedures (control group). The mean and standard deviation of the difference scores in the control group were used to generate Z scores. We used a previously described point system to transform negative Z scores into injury points for each neuropsychometric test. Global performance is presented as average deficit score (sum of injury points divided by the number of completed tests). All patients underwent the procedures with mild sedation. Results were analyzed in 2 ways: group-rate and event-rate analysis. Outcome was dichotomized by defining moderate to severe CD as average deficit score at least 1.5 standard deviations worse than the control group. Fisher tests and multivariate logistic regression models were used to analyze group performance.

Results: Control patients tended to be younger and had a lower incidence of stroke or previous transient ischemic attack. One day after surgery, 41% of patients (10 of 24) treated with CAS developed moderate to severe CD (P = 0.0422). Average deficit score was also significantly higher in the CAS group at 1 day (P = 0.0265). These differences were independent of age and history of stroke/transient ischemic attack. Interestingly, we found that the absence of oral statin medication may increase the probability of CD. By 1 month, 9% of patients (1 of 11) treated with CAS presented with CD. Other patients were lost to follow-up.

Conclusion: CAS is associated with a decline in cognitive performance that is at least moderate 1 day after surgery.

FIGURE 1

Group-rate analysis at 1 day. Patients undergoing CAS accumulated more deficit points on average at 1 day (non-parametric p = 0.0265). Points above the red 1.5 SD cutoff line identify patients with moderate to severe cognitive dysfunction.