The risk of major stroke following a symptomatic episode was convincingly shown to be related to the severity of stenosis in the NASCET and ECST trials. It was also noted that the risk of major stroke was highest soon after the symptomatic episode [WME73,Eur98]. In the NASCET trial surgery was performed within 120 days of the transient ischaemic attack. In the ECST trial it was evident that the risk of stroke in the medically treated patients decreased with time following the transient neurological deficit. The risk of major stroke had fallen back to the background annual risk of 3% by the third year [Eur98]. This implies that patients being considered for carotid endarterectomy following a symptomatic episode should have their surgery as soon as possible after a transient deficit and that they should only be considered for surgery as a symptomatic patient within this increased risk period.
Conversely, surgery should probably not be performed in patients with acute well established stroke. The perioperative morbidity is high in this situation and it is advisable to wait until the patient has been asymptomatic for an interval. Concrete data is lacking but this period is probably between six weeks and three months. A recent report from a German surgical group showed remarkably good results in patients with hemiparesis or coma with a negative CT scan of the brain, a duplex showing that the ipsilateral artery was stenosed but not occluded when surgery was performed within 24 hours.