Are strokes predictable with noninvasive methods: a five-year follow-up of 303 unoperated patients.
To determine the correlation between the degree of internal carotid arterial stenosis demonstrated by noninvasive tests and the risk of subsequent stroke, 303 consecutive patients who underwent cerebrovascular evaluation with the Hokanson ultrasonic arteriograph were reviewed retrospectively. Ninety percent of the patients were followed up for 5 years or until the time of death. Stroke occurred in 41 (13.5%) patients. There was a significant correlation (p = 0.04) between the incidence of stroke and severity of disease: greater than or equal to 50% stenosis (19%), 0% to 49% stenosis (11%), and no stenosis (10%). Stroke as a presenting complaint carried the highest risk of subsequent neurologic defect (24%), but the risk in patients without symptoms was appreciable (15%). Life-table analysis indicated that the incidence of stroke was low (less than 3%) in the asymptomatic and nonhemispheric group during the first 2 years after evaluation when the degree of stenosis was less than 50%. Thereafter, the stroke rate increased. Half the deaths were due to myocardial infarction; the risk of death from cardiac causes was doubled in patients with greater than 50% stenosis. It is concluded that the demonstration of hemodynamically significant stenosis does select a group of patients at increased risk for subsequent stroke and myocardial infarction, but lesser degrees of stenosis do not exclude future neurologic events.