INFLUENCE OF THE ANGIOGRAPHIC INTERNAL CAROTID-ARTERY STENOSIS ASSESSMENT METHOD ON INDICATING CAROTID SURGERY

Background: To estimate the influence of different kinds of angiograph ic internal carotid artery (ICA) stenosis assessment methods on clinic al decision making on carotid surgery. Method: One hundred angiographi cally proven ICA lesions in 65 patients (54 men, 11 women, mean age +/ -SD, 64+/-8 years) were evaluated by simultaneous biplane angiography. The angiograms were analyzed using three kinds of linear diameter red uction methods [North American (NASCET), and European (ECST) carotid s urgery trial method, common carotid artery method(CC)], and five area reduction methods reflecting more accurately the anatomical degree of stenosis [squared NASCET, ECST and CC (N-2, E-2, CC2), combined stenos is estimation of two projections (NASCET-bi, ECST-bi)]. All lesions we re additionally evaluated by continuous wave (cw-)Doppler ultrasound p rior to angiography. Between method agreement on classifying the lesio ns into stenosis < 70% and into stenosis greater than or equal to 70% was calculated by means of kappa statistic. Results: The degree of ste nosis (median and inter-quartile range) ranged between 65% (38-82) by means of NASCET and 91% (87-93) by means of CC2. Thirty-seven ICA sten oses would have been operated using NASCET, but 82 using CC2. Between method agreement on assessing high grade ICA stenosis ranged from poor (kappa value 0.17 for the pair NASCET/CC2) to excellent (kappa value 0.92 for the pair NASCET-bi). Cw-Doppler ultrasound showed a good agre ement (kappa value 0.72-0.80) with all angiographic methods using an a rea reduction formula apart from CC2. The agreement was moderate betwe en cw-Doppler and NASCET and ECST respectively. Conclusion: The clinic al decision to operate on an ICA stenosis will strongly be influenced by the angiographic method used. Because reliable clinical data exist only for the NASCET and ECST method these two angiographic stenosis as sessment method should be used for clinical decision making.