Carotid Disease Classification: Impact of the 2021 Intersocietal Accreditation Commission Updated Recommendations vs 2003 Society of Radiologists in Ultrasound Consensus Conference Criteria

In 2021, the Intersocietal Accreditation Commission (IAC) introduced modified criteria for carotid duplex interpretation based on peak systolic velocity (PSV) and PSV ratio. The most significant change compared to the 2003 Society of Radiologists in Ultrasound (SRU) criteria involved re-defining the thresholds for <50 and 50% to 69% stenosis ranges. Patients identified in <50% vs 50% to 69% ranges may face different disease severity assignments, variable surveillance protocols, medical management approaches, and recommendations for intervention. Facilities may experience altered payment coverage, issues of staff re-training, and questions from referring physicians regarding patient treatment and disease management expectations. The objective of this study was to assess the impact of re-defining these stenosis ranges using the 2021 IAC criteria vs the SRU criteria. Anonymized patient data from carotid duplex examinations were collected as part of an internal laboratory quality improvement strategy. These data were analyzed in an electronic database using the IAC and SRU threshold criteria to determine the degree of carotid stenosis. Patients with normal arteries, unilateral studies, or complete occlusions were excluded. Of the 1000 patients considered, 850 met the eligibility criteria. Using PSV: for the right carotid, 242 (28.5%) showed a change and 608 (71.5%) showed no change in stenosis classification; for the left carotid, 228 (27%) showed a change and 622 (73%) showed no change. All changes were a downgrading of disease to <50% stenosis. Using PSV ratio: for the right carotid, re-assignment of 53 (22% of changed, 6% of total cohort); for the left carotid, re-assignment of 48 (21% of changed, 5.6% of total cohort). All changes resulted in re-assignment to the 50% to 69% stenosis category. Implementation of the IAC criteria resulted in patients being re-assigned to lower stenosis categories (27% for PSV and 21% for PSV ratio). The impact of these changes on patient care and facility logistics needs careful consideration.