Risk, causes, and prevention of ischaemic stroke in elderly patients with symptomatic internal-carotid-artery stenosis

Background Carotid endarterectomy benefits patients with symptomatic stenosis of 70–99% in the internal carotid artery, with smaller benefit for 50–69% stenosis. The benefit of carotid endarterectomy in patients of 75 years and older remains unclear. Methods Patients aged 75 years or older from the North American Symptomatic Carotid Endarterectomy Trial were compared with those aged 65–74 years and less than 65 years for baseline characteristics and risk of ipsilateral ischaemic stroke at 2 years by degree of stenosis and treatment group. Findings Among patients with 70–99% stenosis, the absolute risk reduction of ipsilateral ischaemic stroke with carotid endarterectomy was 28·9% (95% CI 12·9–44·9) for patients aged 75 years or older (n=71), 15·1% (7·2–23·0) for those aged 65–74 years (n=285), and 9·7% (1·5–17·9) for the youngest group (n=303). Among patients with 50–69% stenosis, the absolute risk reduction was significant only in those of 75 years and older (n=145; 17·3% [6·6–28·0]). The perioperative risk of stroke and death at any degree of stenosis was 5·2% for the oldest group, 5·5% for 65–74 years, and 7·9% for less than 65 years. The number of patients aged 75 years or older needed to treat to prevent one ipsilateral stroke within 2 years was three with 70–99% stenosis and six with 50–69% stenosis. Interpretation In the prevention of ipsilateral ischaemic stroke, elderly patients with 50–99% symptomatic carotid stenosis benefited more from carotid endarterectomy than younger patients did. To achieve this treatment benefit, surgeons must be skilled and patients with other lifethreatening illnesses must be excluded.