Ten year cerebrovascular morbidity and mortality in 68 year old men with asymptomatic carotid stenosis

Abstract

To study the natural course of carotid artery stenosis detected by ultrasonography. Prospective cohort study. Baseline examination in 1982-3 included ultrasound examination of carotid arteries, measurement of ankle-brachial blood pressure index, and detection of atrial fibrillation by 24 hour ambulatory electrocardiography. Malmö, a city in southern Sweden with 230,000 inhabitants. 470 men aged 68 years randomly selected from the population. Incidence of stroke and transient ischaemic attack and all cause mortality during 10 years of follow up in relation to carotid stenosis, leg artery disease (ankle-brachial blood pressure index below 0.9), and atrial fibrillation. Fifty men had a stroke; six of these were haemorrhagic. Another 11 had a transient ischaemic attack. Eighteen of the men with carotid stenosis (21.6 events/1000 person years) and 43 of the men with normal carotid arteries (14.8 events/1000 person years) had a stroke or transient ischaemic attack (P = 0.188). Men with atrial fibrillation had an increased rate of cerebrovascular events (36.7/1000 person years (P = 0.048). The highest rate was found in men with asymptomatic disease of the leg arteries (38.6/1000 person years) (P < 0.001). The increased risk of stroke or transient ischaemic attack in this group remained after multivariate analysis (relative risk 2.0; 95% confidence interval 1.1 to 3.7). In this cohort carotid stenosis was not associated with an increased risk of stroke. Part of this lack of association was explained by the high mortality from ischaemic heart disease in men with severe stenosis. Twenty seven of the 61 cerebrovascular events, however, occurred in men who had normal carotid arteries, normal ankle pressure, and no atrial fibrillation.