Impact of 2023 updated Intersocietal Accreditation Commission interpretation criteria for carotid stenosis on thresholds for treatment of carotid artery disease.

Abstract

In 2023, the Intersocietal Accreditation Commission (IAC) released recommendations to standardize carotid duplex ultrasound (CDU) interpretation among all noninvasive vascular laboratories. Peak systolic velocity (PSV) was recommended as the primary parameter to interpret degree of internal carotid artery (ICA) stenosis, with the threshold for ≥70% ICA stenosis of PSV >230 cm/s. Our study evaluated the impact of adopting these updated IAC criteria for interpretation of high-grade carotid artery stenosis. We performed a single-center retrospective study of patients who underwent CDU from July 2021 to June 2023 at an IAC-accredited outpatient vascular laboratory. PSV, end-diastolic velocity (EDV), and ICA/common carotid artery (CCA) ratio were obtained for each ICA examined. The primary outcome was the proportion of ICAs with ≥70% stenosis using PSV of >230 cm/s compared with our laboratory threshold of >275 cm/s. ICAs were then analyzed incorporating EDV and ICA/CCA ratio and compared with interpretations using PSV alone. For generalizability, the number of ICAs from our patient dataset categorized as ≥70% stenosis based on >230 cm/s was compared with published PSV thresholds in 10 cm/s increments to determine at what point these changes in proportion became significantly different. A total of 3141 ICAs were analyzed from 1038 patients. Adopting the IAC-recommended threshold resulted in a 52% increase in those categorized as ≥70% (266 vs 406; P < .0001) compared with our vascular laboratory PSV threshold. Adding ICA/CCA ratio >4 to the PSV criteria, this difference was 17% (176 vs 206; P < .0001). Adding EDV >100 cm/s to the PSV criterion, the increase was only 1.8% and no longer significant (114 vs 116; P = .157). Finally, adding both EDV >100 cm/s and ICA/CCA ratio >4 to the PSV criterion, the increase was 1.1% (91 vs 92; P = .317). There were no significant differences between women and men in the proportion with ≥70% stenosis at either threshold. Based on published PSV ranges from 150 to 360 cm/s, a total of 857 ICAs were identified as having ≥70% stenosis. Significant numbers of ICAs changed category for PSV thresholds of ≤220 or ≥240 cm/s, compared with the number of ICAs using 230 cm/s. This study demonstrated differences in interpretation for ≥70% ICA stenosis using the updated IAC guideline of PSV >230 cm/s as the primary parameter compared with our laboratory value of 275 cm/s. A significant number of patients would change categorization from <70% to ≥70% stenosis, potentially leading to differences in patient management. However, inclusion of EDV and ICA/CCA ratio mitigated any statistically significant difference in the number of patients recategorized, and demonstrated the importance of multiple parameters in CDU interpretation.