Selective Shunting in Carotid Endarterectomy Based on Circle of Willis Assessment Reduced Perioperative Neurologic Event and Stroke Rates

In previous research conducted at our center in 2015, we found a strong association between missing Circle of Willis (CoW) segments and immediate neurologic events, with an odds ratio of 11.12. Based on these findings, our center changed its carotid endarterectomy (CEA) protocol to shunt cases based on CoW assessment selectively. The aim of this study is to evaluate the effectiveness of the new selective shunting protocol in reducing the incidence of perioperative neurologic events after CEA. We prospectively collected the clinical data and outcomes of 1899 patients who underwent CEA between January 2013 and June 2018. The study period was divided into two parts: the first period, from January 2013 to December 2015, included 1043 patients who received dominantly CEA without a shunt, or a shunt was used randomly based on CoW independent factors. The second period, from January 2016 to June 2018, included 856 patients who received CEA with selective shunting based on preoperative CoW assessment, using mainly computed tomography angiography. We selectively used a shunt when the anterior semicircle and ipsilateral posterior semicircle of the CoW both had missing or hypoplastic (diameter ≤0.8 mm) segments. We collected and analyzed clinical data and outcomes as the incidence of immediate neurologic event (INE), perioperative stroke, and operative details such as shunt utilization. INE was defined as any transient ischemic attack and stroke diagnosed after the procedure. The shunt usage increased from 54/1043 (5.2%) to 117/856 (13.7%) (P < .001). The incidence of INE was significantly lower in the selective shunting group (16/856 [1.9%]) than in the nonselective shunting group (57/1043 [5.5%], P < .001). The overall stroke rate was also significantly lower in the selective shunting group compared with the nonselective shunting group (10/856 [1.2%] vs 23/1043 [2.2%]; P = .048). Of the 10 strokes in the selective shunt group, none were awakening strokes. Previously, 13 of the 23 cases had been detected on recovery. This means that the rate of wake-up strokes (INE strokes) is also significantly lower (0/856 vs 13/1043 [1.2%], P < .001). The use of selective shunting resulted in a higher overall shunt usage, but this was associated with a lower incidence of perioperative neurologic events compared with nonselective shunting. Our findings suggest that selective shunting based on the assessment of CoW segments may be a useful strategy to reduce the risk of perioperative neurologic events in patients undergoing CEA.