Risk, Causes and Prevention of Ischemic Stroke in Elderly Patients with Symptomatic Internal Carotid Artery Stenosis
Background. Atherosclerosis is an important cause of stroke in the elderly. Carotid endarterectomy (CE) benefits patients with 70–99% symptomatic internal carotid artery (ICA) stenosis, less for patients with 50–69% stenosis. The benefit of CE in elderly patients (≥75 years) requires evaluation. Methods. Elderly patients with symptomatic ICA stenosis were compared to those 65–74 years and <65 years in regards to baseline characteristics, risk of ipsilateral ischemic stroke at 2 years by degree of stenosis and treatment group and risk of ischemic stroke in the territory of an asymptomatic contralateral carotid artery. Results. The risk of ipsilateral ischemic stroke was highest in the medically-treated elderly regardless of the degree of stenosis. Among 659 patients with 70–99% stenosis, the absolute risk reduction (ARR) of ipsilateral ischemic stroke by CE was 28.9% for patients ≥75 years (N=71), 15.1% for 65–74 years (N=285) and 9.7% for <65 years (N=303). Among patients with 50–69% stenosis, the ARR was significant only in those ≥75 years (N=145) with an ARR of 17.3%. The perioperative risk of stroke and death at any degree of stenosis was less in the elderly: 5.1% for patients ≥75 years, 5.4% for 65–74 years and 7.8% for <65 years. The numbers of patients ≥75 years with 70–99% and 50–69% stenosis needed to treat (NNT) by CE to prevent one ipsilateral stroke within 2 years were 3 and 6, respectively. For 60–99% asymptomatic contralateral ICA stenosis, the 2 year risk of stroke was 7.8% in patients ≥75 years and 7.4% in those < 75 years. The risk of ischemic stroke at 5 years in the territory of a 60–99% asymptomatic ICA stenosis was higher in patients ≥75 years (24.8%) than in patients <75 years (14.9%). Conclusions. In the prevention of ipsilateral ischemic stroke, elderly patients with 50–99% symptomatic carotid stenosis benefited more from CE than younger patients. To achieve this benefit, patients must be carefully selected, excluding those with other life threatening illnesses.