Natural history of carotid artery occlusion contralateral to carotid endarterectomy

BACKGROUND: The natural history of patients with carotid artery occlusion is controversial. A few studies have concluded that patients with internal carotid artery occlusion carry a high risk of neurologic events. None of these previously reported studies analyze the natural history of internal artery occlusion contralateral to carotid endarterectomy (CEA), except for a small series including a subset of patients from two randomized trials, the Asymptomatic Carotid Atherosclerosis Study and the North American Symptomatic Carotid Endarterectomy Trial. This study analyzes the natural history of patients with carotid artery occlusion contralateral to CEA, specifically assessing long-term neurologic events occurring in the hemisphere associated with the occluded carotid artery. METHODS: Of the 599 CEAs in 544 patients that were included in two previously updated prospective studies, 63 patients had contralateral internal carotid artery occlusion, and their perioperative and long-term outcomes were evaluated. A Kaplan-Meier analysis was used to estimate the rate of freedom from late stroke occurring in the hemisphere ipsilateral to the occluded carotid artery. The stroke-free survival rate was also noted. RESULTS: Mean follow-up was 58 months (range, 1 to 147 months). One perioperative stroke (1.6%) occurred, which was not in the cerebral hemisphere ipsilateral to the occluded carotid artery. Two late strokes (3.2%) and nine transient ischemic attacks (TIAs) (14.3%) occurred involving the hemisphere of the occluded carotid artery. There were also three late TIAs (4.8%) and no late strokes involving the hemisphere supplied by the operative site. There were a total of 14 late deaths. Fifteen patients had late > or =50% restenosis of the operative side. Six of these had neurologic events (TIA/stroke) involving the hemisphere of the occluded carotid artery, in contrast to five of 48 patients with no restenosis who had neurologic symptoms (P < .001). Freedom from late strokes in the hemisphere ipsilateral to the occluded carotid artery at 1, 3, 5, and 10 years was 98%, 96%, 96%, and 96%, respectively. The stroke-free survival rates at 1, 3, 5, and 10 years were 90%, 87%, 80%, and 59%, respectively. CONCLUSIONS: The natural history of carotid artery occlusion contralateral to CEA is relatively benign. This may suggest a protective effect of carotid endarterectomy on the cerebral hemisphere ipsilateral to the carotid occlusion from late strokes.