Causes of perioperative stroke after carotid endarterectomy: special considerations in symptomatic patients

In order to maximize the efficacy of carotid endarterectomy (CEA), the rate of perioperative stroke must be kept to a minimum. A recent analysis of carotid surgery at our institution found that most perioperative strokes were due to technical errors resulting in thrombosis or embolization. From 1992 through 1997 we have performed nearly 1200 additional CEAs; the purpose of this study was to examine recent trends in the causes of perioperative stroke, with specific attention to differences in symptomatic and asymptomatic patients. The records of 1041 patients undergoing 1165 CEAs were reviewed from a prospectively compiled database. Analysis of these data showed that a history of preoperative stroke appears to increase the risk of perioperative stroke after CEA. Surgical factors associated with perioperative stroke include an inability to tolerate clamping, use of an intraarterial shunt, and having surgery performed under general anesthesia; these factors are clearly interrelated and only the use of intraarterial shunting remains a risk factor by multivariate analysis. Over half of all perioperative strokes (54%) appear to be caused by intraoperative or postoperative thrombosis and embolization. The patient requiring use of intraarterial shunting and/or with a preoperative stroke most likely has a significant watershed area of brain at increased risk of infarction. However, technical errors are still the most common cause of perioperative stroke in these high-risk patients. Such high-risk patients may manifest clinical stroke from small emboli that may be tolerated by asymptomatic clamp-tolerant patients. Technical precision and appropriate cerebral protection are particularly critical for successful outcomes in high-risk patients.