Endarterectomy in patients with symptomatic moderate carotid stenosis of 50 to 69 percent yielded only a moderate reduction in the risk of stroke. Decisions about treatment for patients in this category must take into account recognized risk factors, and exceptional surgical skill is obligatory if carotid endarterectomy is to be performed. Patients with stenosis of less than 50 percent did not benefit from surgery. Patients with severe stenosis (> or =70 percent) had a durable benefit from endarterectomy at eight years of follow-up.

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Some believe that carotid endarterectomy (CEA) for carotid near occlusion is a necessary emergency procedure while others call it dangerous. We used the North American Symptomatic Carotid Endarterectomy Trial (NASCET) data to perform an observational study to examine the safety and benefit of CEA for carotid near occlusion. We divided the data of 659 patients into stenosis groups: 70 to 79%, 80 to 89%, 90 to 94%, and near occlusion. The 106 carotid-near-occlusion patients were subdivided into those with a string-like lumen (n = 29) and those without a string-like lumen (n = 77). Of the 48 patients with near occlusion treated with CEA, 3 (6.3%) had perioperative strokes, similar to the 70-94% stenosis group. Only 1 of 58 patients (1.7%) with near occlusion treated medically had a stroke in the first month, suggesting that CEA is not needed on an emergency basis in this circumstance. For medically treated patients, the 1-year risk of stroke increases with escalating degrees of carotid stenosis, where the risk is 35.1% for patients with 90-94% stenosis. For patients with near occlusion, the 1-year stroke risk diminishes to 11.1%, which approximates the risk for patients with 70-89% stenosis. A comparison of treatment differences indicates that surgery reduces the risk of stroke at 1 year by approximately one-half (p < 0.001), regardless of the degree of stenosis or the subcategory of carotid near occlusion (p = 0.89). Our data suggest that CEA is beneficial for near occlusion and not more dangerous than in patients with 70-94% stenosis, provided that the procedure is performed by an experienced surgeon with a low complication rate.

SUMMARY Three hundred and fifty-two patients with atherosclerotic middle cerebral artery stenosis (MCAS, 53%) or occlusion (MCAO, 47%) have been systematically studied. The study involved all patients entered into the EC/IC Bypass Study with isolated MCA disease or a tandem lesion predominating in the MCA ipsilateral to the ischemic events (18 patients with a tandem lesion of greater magnitude in the internal carotid artery were not included). The Asian patients represented 58% of all Asians entered into the EC/IC Bypass Study, whereas the white patients represented 18% of all whites and the black patients 34% of all blacks. Isolated TIAs were less frequent in MCAO (12%) than in MCAS (34%). Warning TIAs before a stroke occurred in one third of the cases. Presentation with stroke or isolated TIA was not influenced by sex, age, level of MCA obstruction, collateral circulation nor associated carotid disease. In MCAS, no major difference in presentation was found between severe and moderate stenosis. Pure motor hemiparesis occurred in 15% and pure sensory stroke in 2% of the patients with stroke and 30% of the MCA territory infarcts were small and limited to the lentkulocapsular area, confirming that so-called lacunar infarcts may be due to large vessel disease.During follow-up (42 months) of 164 medically-treated patients, further cerebrovascular events (TIA and stroke) occurred in 11.7% of the patients per year. In MCAO the stroke rate was 10.1 % per patient-year and the ipsilateral infarct rate was 7.1% per patient-year. In MCAS, the stroke rate was 9.5% per patientyear and the ipsilateral stroke rate was 7.8% per patient-year. The location and severity of lesion did not influence the occurrence of ipsilateral ischemic events during follow-up. Reopening of an artery-to-artery embolic occlusion of the MCA, with subsequent embollc reocclusion, may explain some of the ipsilateral ischemic events during follow-up. The annual death rate was 3.3% in MCAS and 2.6% in MCAO. Less than 15% of the survivors were severely disabled at the end of follow-up and nearly two-thirds were able to resume previous activities both hi MCAO and MCAS. The type of delayed ischemic events tended to be the same as that of the presenting event, but no factor could significantly predict the occurrence of stroke or death. This study suggests that long-term prognosis of patients with MCA occlusion, who present with TIA or non-devastating stroke, is reasonable.