Effect of Internal Carotid Artery Doppler Peak Systolic Velocity Thresholds for Classifying Ipsilateral Ischemic Stroke Due to Large Artery Atherosclerosis According to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) System

Background: A Doppler peak systolic velocity (PSV) of 125 cm/s has been used to indicate an internal carotid artery 50% stenosis, a marker of large artery atherosclerosis (LAA) when classifying ischemic stroke according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST). Shifting this cut point to 180 cm/s might affect the classification of ischemic stroke. Methods: Color Doppler–assisted measurements of PSV were performed at the baseline visit of a large longitudinal cohort study in the United States: the Cardiovascular Health Study (CHS). Incident ischemic stroke within the following 6 years was ascertained by adjudicated review of medical records. The side of ischemic stroke was recorded. Incidence rates and odds ratios (logistic regression models) were estimated at the respective 125 cm/s and 180 cm/s cut points. Results: Mean age was 72.8 years with 57.6% women. A total of 11 425 bifurcations had PSV measurements. Of the 514 carotid bifurcations with PSV above 125 cm/s, 20 ipsilateral incident strokes were seen, whereas 6 strokes occurred among the 126 bifurcations with PSV above 180 cm/s. Shifting the cut point decreased categorizing ischemic stroke as due to LAA by 70% (14/20). The odds ratio (1.75; 95% confidence interval, 1.01-3.02) of incident stroke for a PSV between 125 cm/s and 180 cm/s was significant (P < .05) when compared with a PSV <125 cm/s. Conclusion: Shifting the PSV cut point for a 50% carotid stenosis from 125 cm/s to 180 cm/s would have significant implications when categorizing ischemic stroke as being associated with LAA.