Guidelines for Carotid Endarterectomy

ince the 1950s carotid endarterectomy has been performed in patients with symptomatic carotid artery stenosis, based on suggestive but inconclusive evidence for its effectiveness. Only during the last 5 years have randomized studies clarified the indications for surgery. In preparing this report, panel members used the same rules of evidence used in the previous report1,2 (Table). Management of Risk Factors Few studies have analyzed control of risk factors in a random- ized, prospective manner following carotid endarterectomy. However, a wealth of data are available regarding the general relationship between risk factor control and stroke risk. These data provide some guidance for the care of endarterectomy patients. Hypertension Hypertension is the most powerful, prevalent, and treatable risk factor for stroke.3 Both systolic and diastolic blood pressure are independently related to stroke incidence. Isolated systolic hypertension, which is common in the elderly, also consider- ably increases risk of stroke. Reduction of elevated blood pressure significantly lowers risk of stroke. Meta-analyses of randomized trials found that an average reduction in diastolic blood pressure of 6 mm Hg produces a 42% reduction in stroke incidence.3,4 Treatment of isolated systolic hypertension in people older than 60 years also reduces stroke incidence by 36% without an excessive number of side effects such as depression or dementia.5 Long-term care of patients after endarterectomy should include careful control of hypertension (Grade A recommendation for treatment of hypertension in general; Grade C recommendation for postendarterectomy care). Perioperative treatment of hypertension after carotid endar- terectomy represents a special situation. Poor control of blood pressure after endarterectomy increases risk of cerebral hyper- perfusion syndrome. 6- 9 This complication is characterized by unilateral headache, seizures, and occasionally altered mental status or focal neurological signs. Neuroimaging may show intracerebral hemorrhages10 -12 or white matter edema.13 Trans- cranial Doppler ultrasound shows elevated middle cerebral artery blood velocity ipsilateral to the endarterectomy and occasionally in the contralateral middle cerebral artery as well.12,14,15 The syndrome is thought to arise from impairment of autoregulation. At greatest risk are patients with severe preoperative internal carotid stenosis and chronic hyperten- sion. The risk is increased when a contralateral severe stenosis is present. Blood pressure should be carefully monitored after carotid endarterectomy, and elevated blood pressure should be aggres- sively treated, particularly in those with early symptoms of cerebral hyperperfusion syndrome (Grade C recommenda- tion). In patients thought to be at risk for hyperperfusion syndrome, blood pressure should be monitored for several days after surgery and for at least 7 days in patients with headaches or new neurological symptoms. Such monitoring may be performed on an outpatient basis as appropriate (Grade C recommendation).13 Transcranial Doppler ultrasound shows promise in early identification of the syndrome and possibly for monitoring therapy but has not been rigorously studied.