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 was a retrospective cohort study including patients undergoing cardiac surgery on cardiopulmonary bypass from January 2006 to March 2018 at the Québec Heart and Lung Institute. Data of patients' preoperative demographic characteristics, operative and postoperative variables were taken from a computerised 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%. Categorised levels of CS severity were identified as independent risk factors for postoperative stroke and/or TIA. There was an almost 3-fold increased risk of postoperative neurologic events in 80%-99% CS vs less severe 50%-79% CS (odds ratio 2.91, 95% confidence interval 1.30-6.54), suggesting that the degree of severity of CS is potentially a strong independent predictor of postoperative neurologic events. CONCLUSIONS:CS is an independent risk factor of postoperative 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 of 80%-99%. The strength of this relationship and potential causality effect should be further explored in a prospective study focusing on this population most at risk.