Abstract 85: Is Progressively Worsening Severity of Internal Carotid Artery Stenosis by Carotid Doppler Ultrasound in Asymptomatic Patients a Risk Factor for Ischemic Stroke?

Abstract

Background: Progressively worsening severity of ICA stenosis has been used as an indication for carotid revascularization in asymptomatic patients. However, limited data exists whether progression in severity is actually associated with ipsilateral cerebral ischemic symptoms. Methods: We analyzed data from the Cardiovascular Health Study participants aged ≥65 years who underwent serial carotid Doppler ultrasound (at baseline and 5 year follow up). The severity was classified into four grades by a central reader: 0-24%, 25-49%, 50-69%, 70-99%, and complete occlusion. We selected patients who were asymptomatic at baseline and not undergone carotid endertectomy. Progressively worsening severity of internal carotid artery stenosis was defined if the severity of ICA with highest velocity at baseline evaluation had increased by one grade or greater at 5 year follow up. Incident cardiovascular events were identified during annual follow-up examinations and at 6-month telephone contact and adjudicated by a central committee. Hazards ratio for cardiovascular events during follow up were estimated using Cox proportional Hazards analysis. Results: Progressively worsening severity of internal carotid artery stenosis was observed in 1551 (26.3%) of 5,888 study participants (57.2% women; mean baseline age, 72.7 ± 5.1 years). The rate of ipsilateral ischemic stroke was similar among patients with and without progressively worsening severity of internal carotid artery stenosis over a mean follow up period (mean ±SD) of 7.3 ± 1 years. The risk of any ischemic stroke was (HR 1.3, 95% confidence interval [CI] 1.0-1.6) but not ipsilateral ischemic stroke (HR 1.4, 95% CI 0.6 - 3.1) was statistically higher among patients with progressively worsening severity of internal carotid artery stenosis after adjusting for age, race, serum cholesterol, diabetes mellitus, blood pressure and cigarette smoking. The risk of MI (HR 1.3, 95% CI 1.1-1.7) was significantly higher among patients with progressively worsening severity of internal carotid artery stenosis. Conclusions: Patients with progressively worsening severity of internal carotid artery stenosis appear to be at higher risk of cardiovascular events but not ipsilateral cerebral ischemic symptoms.