Introduction: Smoking may increase the risk of carotid plaque formation. Smoking’s effect on cerebral blood flow and cognitive function following carotid endarterectomy has not been previously examined. This study’s objective was to determine whether preoperative smoking in patients with carotid stenosis limits cognitive improvement following carotid endarterectomy (CEA).
Methods: Patients with significant unilateral stenosis eligible for CEA were included. Smoking status prior to CEA was documented. Cerebral blood flow in the internal carotid artery (ICA) was obtained using Quantitative Magnetic Resonance Angiography (qMRA). To account for systemic variability, simple flow ratios (ipsilateral/contralateral) were calculated and compared pre- and post-operatively. Cognitive function was assessed at baseline and one, six and twelve months following surgery. Four cognitive domains were tested: attention (TMTA), executive functioning (TMTB), language/verbal fluency (FAS), and learning/new memory (HVLT).
Results: Of thirty-six patients who met eligibility criteria, thirty had follow-up data at either six (n=26) or twelve (n=21) months. The cohort was 50% male and average age was 72 years. Four (13%) patients had symptomatic disease. Twenty patients (67%) were smokers. Preoperative blood flows were comparable for smokers and non-smokers. Following surgery, improvement in the ICA flow ratio was three times greater in nonsmokers than smokers (p=0.032) [Figure 1]. Cognition was assessed as a comparison between smokers and nonsmokers and each individual’s improvement from baseline. The twelve-month assessment showed nonsmokers with a strong trend towards greater percent improvements than smokers in executive functioning (22% versus 8%, p=0.088) and attention (24% versus 5%, p=0.079) [Figure 2]. Nonsmokers showed significant self-improvement at twelve months in attention (p=0.005) and language/verbal fluency (p=0.013), plus marginally significant improvements in the remaining cognitive domains: executive functioning (p=0.097) and learning/new memory (p=0.066). Conversely, at twelve months smokers only significantly improved in learning/new memory (p=0.001).
Conclusions: Preoperative smoking may limit cognitive improvement seen in nonsmokers one year following CEA.
Patient Care: Understanding how outcomes differ for smokers compared to nonsmokers allows physicians to suggest realistic outcome expectations for their patients. Smoking patients with significant unilateral stenosis will likely see improved cerebral blood flow and cognitive function following CEA; however, not to the degree seen in nonsmokers. Carotid revascularization is still indicated to reduce future risk of stroke in both smoking and nonsmoking patients with significant stenosis.
Learning Objectives: By the conclusion of this session, participants should be able to:
1. Describe how smoking affects stenosis patients post-CEA
2. Discuss how outcomes are similar/different between smokers and nonsmokers