Correlation of North American Symptomatic Carotid Endarterectomy Trial (NASCET) angiographic definition of 70% to 99% internal carotid artery stenosis with duplex scanning.
OBJECTIVE
The North American Symptomatic Carotid Endarterectomy Trial (NASCET) has thus far demonstrated conclusive benefit for carotid endarterectomy for patients with symptomatic 70% to 99% internal carotid artery (ICA) stenosis. In the NASCET, ICA stenosis was classified angiographically: % ICA stenosis = (1 - [narrowest ICA diameter/diameter normal distal cervical ICA]) x 100%. However, widely used duplex scan criteria for ICA stenosis correlate with different angiographic categories of high-grade stenosis (50% to 79%, > 80%) and were developed on the basis of estimated bulb diameter. We therefore blindly evaluated with separate observers carotid angiograms from 100 patients who also underwent carotid duplex scanning in our vascular laboratory.


METHODS
"Angiographic stenosis" was calculated as in NASCET. Duplex scan measurements of ICA peak systolic velocity (PSV), ICA end-diastolic velocity, and the ratio of ICA PSV to common carotid artery (CCA) PSV were analyzed for sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy to identify a 70% to 99% ICA stenosis.


RESULTS
Analysis of the data revealed that an ICA PSV/CCA PSV ratio of 4.0 provided the best combination of sensitivity (91%), specificity (87%), positive predictive value (76%), negative predictive value (96%), and overall accuracy (88%) for detection of a 70% to 99% stenosis.


CONCLUSIONS
We conclude duplex scan determination of 70% to 99% stenosis as defined in the NASCET requires the adoption of duplex criteria modified from those in current use in most vascular laboratories.
Moneta
G L
GL
Department of Surgery, Oregon Health Sciences University, Portland 97201.
Edwards
J M
JM
Chitwood
R W
RW
Taylor
L M
LM
Lee
R W
RW
Cummings
C A
CA
Porter
J M
JM
D015901:Angiography, Digital Subtraction / Q000706:statistics & numerical data; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000601:surgery; D016893:Carotid Stenosis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000601:surgery; D003116:Color; D016894:Endarterectomy, Carotid / Q000706:statistics & numerical data; D005069:Evaluation Studies as Topic; D006801:Humans; D009656:North America; D009922:Oregon / Q000453:epidemiology; D011379:Prognosis; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000295:instrumentation / Q000379:methods / Q000706:statistics & numerical data