Predictive Factors of Silent Brain Infarcts after Asymptomatic Carotid Endarterectomy

Background: The optimization of medical treatment regularly challenges the role of carotid surgery for asymptomatic patients. Current research seeks to determine which of these patients will benefit most from surgery. The goal of this study was to identify in a multicenter study, using magnetic resonance imaging (MRI), the risk factors for postoperative silent cerebral ischemic lesions after carotid surgery for asymptomatic stenosis. Methods: The multicenter, retrospective study included patients with asymptomatic severe carotid stenosis suitable for surgical treatment and who did not have a history of cerebral ischemia. A diffusion MRI scan was performed the day before and in the 3 days after the procedure. An analysis by an independent neuroradiologist determined the presence of preoperative silent ischemia and the appearance of new lesions postoperatively. The analysis also took into account the plaque type, lesions of supra-aortic trunks, the circle of Willis, the type of surgery, and anesthesia, shunt use, and clamp time. Results: Between April 2011 and November 2015, 141 patients were included. The mean degree of carotid stenosis in the patients who underwent surgery was 78.2% +/- 6.5, with 9 (6.4%) cases of contralateral stenosis >= 70% and 6 (4.3%) of which were thrombosis. The circle of Willis was incomplete in 23 (16.3%) patients. Twenty-one (14.9%) plaques were of high embolic risk. The preoperative MRI found 34 (24.1%) patients with embolic ischemic lesions. The majority of procedures were eversions performed under general anesthesia, 7 (5%) required a shunt, and the mean clamp time was 39 +/- 16 min. The postoperative MRI revealed that 10 (7%) patients had a new ischemic lesion on the operated side. None of these lesions were symptomatic. On multivariate analysis, the risk factors for appearance of a new ischemic lesion on the operated side were significant severe stenosis of the vertebral artery ipsilateral to the lesion (odds ratio [OR] = 9.2, 95% confidence interval [CI] [ 2.1-39.8], P = 0.003) and insertion of a shunt (OR = 9.1, 95% CI [1.1-73.1], P = 0.039). The 30-day follow-up showed one death at D4 due to hemorrhagic stroke on the operated side and one contralateral stroke. None of the study patients had a myocardial infarction. Conclusions: In this multicenter study, the rate of silent ischemic lesions in asymptomatic carotid surgery showed 43.3% of preoperative silent ischemic lesions and 9.2% of new silent lesions after surgery. The use of a shunt and presence of ipsilateral vertebral stenosis are risk factors for perioperative embolism.