Stroke risk from symptomless extracranial arterial disease.

The natural history of a prospectively selected group of neurologically symptomless patients with extracranial arterial disease (EAD) was studied. 23 of 122 patients died over a period of follow-up of from eleven to thirty-six months (mean = seventeen), but only 3 from stroke and 10 from cardiac failure. Among those patients still alive 8 reported transient ischaemic attacks, 1 a stroke, and 90 remain symptomless. Thus, by life-table analysis, the cumulative stroke rate was only 7%, irrespective of death or survival, the same as the average risk of death in a normal population. However, by subsequent continuous-wave Doppler examination of carotid and vertebral arteries, the probability of EAD progression was 85%. Involvement of initially unaffected arteries occurred either alone (25) or in combination with a deterioration of the original stenosis (14)--the latter alone was seen in 9 patients. A combined carotid and vertebral lesion was found to be the only significant indicator of cerebrovascular risk, which was six times greater than that for unilateral or bilateral carotid lesions.