Carotid plaques increase the risk of stroke and subtypes of cerebral infarction in asymptomatic elderly: the Rotterdam study

BACKGROUND: Few studies have quantified the relation between carotid plaques and stroke in asymptomatic patients, and limited data exist on the importance of location of plaques or the association with subtypes of cerebral infarction. We investigated the relationship between carotid plaques, measured at different locations, and risk of stroke and subtypes of cerebral infarction in a population-based study. Methods and Results- The study was based on the Rotterdam Study and included 4217 neurologically asymptomatic subjects aged 55 years or older. Presence of carotid plaques at 6 locations in the carotid arteries was assessed at baseline. Severity was categorized according to the number of affected sites. After a mean follow-up of 5.2 years, 160 strokes had occurred. Data were analyzed using Cox proportional hazards regression. Plaques increased the risk of stroke and cerebral infarction approximately 1.5-fold, irrespective of plaque location. Severe carotid plaques increased the risk of nonlacunar infarction in anterior (RR 3.2 [95% CI, 1.1 to 9.7]) but not in posterior circulation (RR 0.6 [95% CI, 0.1 to 4.9]). A >10-fold increased risk of lacunar infarction was found in subjects with severe plaques (RR 10.8 [95% CI, 1.7 to 69.7]). No clear difference in risk estimates was seen between ipsilateral and contralateral infarction. CONCLUSIONS: Carotid plaques increase the risk of stroke and cerebral infarction, irrespective of their location. Plaques increase the risk of infarctions in the anterior but not in the posterior circulation. It is likely that carotid plaques in neurologically asymptomatic subjects are both markers of generalized atherosclerosis and sources of thromboemboli.