New duplex ultrasound scan criteria for managing symptomatic 50% or greater carotid stenosis

Purpose: The North American Symptomatic Carotid Endarterectomy Trial (NASCE T) showed that selected patients benefited from surgery when their carotid artery was 50% or more stenosed. This study assessed the accuracy of color- flow duplex ultrasound scanning (DUS) parameters to detect 50% or greater c arotid artery stenosis and to determine the situations in which carotid end arterectomy (CEA) without angiography could be justified. Methods: From March 1, 1995, to December 1, 1995, all patients considered f or CEA were studied with DUS and carotid angiography. Results of the two te sts were blindly compared. DUS measurements of internal carotid artery (ICA ) peak systolic velocity (PSV), end diastolic velocity, and ratio of the IC A to common carotid artery PSV (ICA/CCA) were subjected to receiver operato r characteristic curve analysis to determine the most accurate criterion pr edicting 50% or greater angiographic stenosis. The criterion for identifyin g patients for CEA without angiography was selected from criteria with a hi gh positive predictive value (PPV) and sensitivity. Results: A total of 188 carotid bifurcations were available for comparison. A PSV (ICA/CCA) of 2 or higher was the most accurate criterion for detecti on of 50% or greater stenosis, with an accuracy rate of 93% (sensitivity, 9 6%; specificity, 89%; PPV, 92%). A PSV (ICA/CCA) of 3.6 or higher was the b est criterion for identifying candidates for CEA who had not undergone earl ier angiography, with PPV, sensitivity, specificity, and accuracy rates of 98%, 77%, 98%, and 86%, respectively. Conclusion: These redefined criteria detect the NASCET-defined threshold le vel of 50% or greater ICA stenosis, above which CEA results in stroke reduc tion. A management algorithm based on these criteria should help to minimiz e both angiography and unnecessary intervention.