Patterns of Acute Ischemic Strokes After Carotid Endarterectomy and Therapeutic Implications

Acute ischemic strokes following surgical treatment of carotid stenosis lead to substantial disability and mortality, and vascular mechanisms underlying their development are not fully elucidated. The goal of this study was to analyze the topographic patterns of acute ischemic stroke following carotid endarterectomy (CEA) on diffusion-weighted and perfusion-weighted magnetic resonance imaging (MRI).

Data were retrospectively collected from consecutive patients who underwent CEA and developed postoperative acute ischemic stroke. Based on the MRI data sets, the lesion patterns of acute stoke were characterized. Morphology of the circle of Willis, the 3-D time-of-flight (3D-TOF) of the cerebral arteries, and status of the carotid circulation were also analyzed in order to determine the vascular mechanisms involved in stroke development.

Between January 2008 and May 2015, 821 patients were treated surgically for a symptomatic or asymptomatic carotid stenosis at the University Hospital of Nice. Nineteen (2.3%) patients had an acute ischemic stroke after surgery. Among them, 11 (57.9%) patients had a territorial infarction and 8 (42.1%) patients had an internal watershed infarction, cortical watershed infarction, or mixed border zone infarction. According to imaging data sets, embolic mechanism of stroke was reported for 12 (63.2%) patients, hemodynamic mechanism for 2 (10.5%) patients, and mixed mechanism for 5 (26.3%) patients. An asymmetry on 3D-TOF was observed in 60% and 50% of patients with hemodynamic and mixed stroke and in 25% of patients with embolic stroke. The latter 2 patients with embolic stroke underwent successful mechanical thrombectomy using stent-retriever devices.

In this cohort, embolic mechanism leading to postoperative stroke was more frequently observed than hemodynamic mechanism. Immediate characterization of the cerebral lesion by postoperative brain MRI is of utmost importance because it may rapidly identify patients eligible for treatments such as mechanical thrombectomy.