Evolution and management of asymptomatic carotid stenosis.

About 4% of adults have asymptomatic neck bruits, and this frequency increases with age. Only a small number of these (about 25%), however, have asymptomatic carotid stenosis (ACS), and only 10% of these have stenoses > 75%. The vascular outcome for patients with ACS depends upon the severity of carotid stenosis, all outcomes worsening after 75-80% stenoses. For stenoses < 50%, annual stroke rate is about 1% and does not change in stenoses 50-75%, but over 75%, annual stroke rate increases to 3.3% per year. Ischaemic cardiac event rate is 2.7% annually for stenoses < 50%, 6.6% for those 50-75%, and 8.3% for stenoses > 75%. Annual vascular death rates also rise from 1.8%, 3.3% and 6.5% respectively. Stroke risk factors such as hypertension and smoking are important in early plaque formation, but when plaques become stenosing, local hemodynamic factors such as turbulence are the major factors in arterial remodelling. No medical or surgical therapy has yet been found effective, but current surgical randomized trials may reveal the answer in the near future.