Relationship Between the Degree of Carotid Stenosis and the Risk of Stroke in Patients Undergoing Cardiac Surgery.

BACKGROUND: The impact of carotid stenosis (CS) in patients undergoing cardiac surgery remains controversial. The aim of this study was to evaluate the association between carotid stenosis and stroke and/or transient ischemic attack (TIA) in patients undergoing cardiac surgery on cardiopulmonary bypass.

METHODS: This is a retrospective cohort study including patients undergoing cardiac surgery on cardiopulmonary bypass between January 2006 and March 2018 at the Quebec Heart and Lung Institute. Data of patients' preoperative demographic characteristics, operative and postoperative variables were taken from a computerized database and patients' charts. Univariate and multivariate analyses were performed.

RESULTS: A total of 20,241 patients were included in the study. Among those who had received preoperative carotid ultrasound, 516 (2.6% of the total population) had unilateral or bilateral CS ≥50%. Categorized levels of carotid stenosis severity were identified as independent risk factors for post-operative stroke and/or transient ischemic attack occurrence. There was an almost three-fold increased risk of post-operative neurologic events in 80-99% CS vs. less severe 50-79% CS [OR 2.91; IC95% (1.30-6.54)] suggesting that the degree of severity of CS is potentially a strong independent predictor of post-operative neurologic events.

CONCLUSIONS: CS is an independent risk factor of post-operative stroke and/or TIA. This study suggests for the first time that the risk of stroke increases with the degree of severity of CS, with the greatest risk being for CS between 80-99%. The strength of this relationship and potential causality effect should be further explored in a prospective study focusing on this most at risk population.