Background and Purpose: Perioperative stroke is a well-recognized complication of carotid endarterectomy (CEA), but well-performing prediction models do not exist for it. Our aim was to identify novel predictors for perioperative ischaemic cerebrovascular events (iCVEs), emphasizing cerebrovascular imaging and potential biomarkers for stroke in carotid stenosis (CS) patients in a well-characterized prospective CS cohort., Methods: Helsinki Carotid Endarterectomy Study 2 is an observational prospective and consecutive cohort study of CS patients subjected to CEA during 2012-2015. The associations between perioperative stroke and transient ischaemic attack (iCVEs) and potential predictive factors were evaluated by univariate and Cox regression analyses., Results: Of 488 operated CS patients, 33 (7%) sustained an iCVE including 21 (4%) ischaemic strokes. In univariate analysis, moderate ipsilateral CS (hazard ratio [HR] 2.14, 95% confidence interval [CI] 1.08-4.23), covert or chronic ipsilateral brain infarct in imaging (HR 2.27, 95% CI 1.09-4.76) and severe cerebral small vessel disease (HR 3.36, 95% CI 1.04-10.88) appeared as novel risk factors for perioperative iCVE. In Cox proportional hazards regression modelling, female gender (HR 3.03, 95% CI 1.30-7.04), a history of coronary heart disease (HR 3.59, 95% CI 1.52-8.47), covert or chronic ipsilateral infarct (HR 2.32, 95% CI 1.01-5.34) and severe small vessel disease (HR 2.63, 95% CI 1.07-6.47) were the strongest independent predictors of perioperative iCVE., Conclusions: In addition to the previously reported clinical risk factors, it was found that imaging markers of past cerebrovascular disease, covert or chronic ipsilateral infarct and severe small vessel disease, and moderate ipsilateral stenosis are associated with perioperative iCVEs., (© 2024 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)