PROPOSED NEW DUPLEX CLASSIFICATION FOR THRESHOLD STENOSES USED IN VARIOUS SYMPTOMATIC AND ASYMPTOMATIC CAROTID ENDARTERECTOMY TRIALS

Current duplex ultrasound criteria for internal carotid artery (ICA) s tenosis (1%-15%, 16%-49%, 50%-69%, 70%-99%) may not be applicable to t hreshold stenoses used in symptomatic (North American Symptomatic Caro tid Endarterectomy Trial [NASCET], Veterans' Administration [VA]) and asymptomatic (Asymptomatic Carotid Atherosclerosis Study, VA) carotid endarterectomy (CEA) trials. This, along with increasing reports advoc ating CEA based on duplex results alone, prompted us to identify (1) n ew velocity criteria consistent with threshold stenoses used by these trials, and (2) velocity criteria with a high positive predictive valu e (PPV) (> 95%) and accuracy for detecting greater than or equal to 60 % and greater than or equal to 70% ICA stenoses. This is the first stu dy to propose criteria which can be used for all current CEA trials. T he color duplex ultrasound (CDU) and arteriogram results of 462 ICAs w ere analyzed in blind fashion. Angiographic stenosis was calculated as in NASCET. Three velocity criteria (peak systolic velocity [PSV] of t he ICA, end diastolic velocity [EDV] of the ICA, and the ratio of the PSV of the ICA/common carotid artery) were recorded and subjected to r eceiver operator characteristic curves (ROC) analysis to determine opt imum criteria for identifying ICA stenoses of greater than or equal to 30%, greater than or equal to 50%, greater than or equal to 60%, and greater than or equal to 70%-99%. For greater than or equal to 30% ste nosis (st): PSV greater than or equal to 120 cm/sec had an overall acc uracy (OA) of 87%, sensitivity (sen.) of 93%, specificity (spec.) of 6 7%, PPV of 90%, and negative predictive value (NPV) of 77%; for greate r than or equal to 50% st: PSV greater than or equal to 140 cm/sec had an OA of 93%, sen. of 92%, spec. of 95%, PPV of 97%, and NPV of 89%; for greater than or equal to 60% st: PSV greater than or equal to 150 cm/sec and an EDV of greater than or equal to 65 had an OA of 90%, sen . of 82%, spec, of 97%, PPV of 96%, and NPV of 86%; for greater than o r equal to 70%-99% st: PSV greater than or equal to 150 cm/sec and an EDV of greater than or equal to 90 had an OA of 92%, sen. of 85%, spec , of 95%, PPV of 91%, and NPV of 92%. An ICA-PSV and EDV of 150, 65, a nd 150, 110 had the best PPV (greater than or equal to 95%) in detecti ng greater than or equal to 60% and greater than or equal to 70% st, r espectively. When these new criteria are used, CDU can accurately dete ct threshold stenoses used by various CEA trials. Selected velocities with a high PPV (> 95%) may be used as the sole preoperative imaging.