Abstract DP313: Characterizing PlaqueRADS Across Stroke Etiologies: A CTA and Vessel Wall Imaging Study in Unilateral Anterior Circulation Stroke.

Background and Aims: High-risk carotid plaque features may contribute to atherosclerotic ischemic stroke beyond stenosis severity. PlaqueRADS is a multimodal grading system integrating plaque vulnerability markers, but its patterns using CTA plus vessel wall imaging (VWI) across stroke etiologies remain unclear. We aimed to compare PlaqueRADS distributions across etiologic subtypes and explore whether ipsilateral scoring provides insights into ESUS mechanisms. Methods: We retrospectively studied patients with unilateral anterior circulation ischemic stroke at a single center who underwent CTA+VWI and met diagnostic criteria for cardioembolic (CE) or large-artery atherosclerotic (LAA) per TOAST, and ESUS per 2022 criteria excluding high-risk PFO. PlaqueRADS was independently scored by three radiologists, excluding cases without bilaterally evaluable arteries. Between-group comparisons were performed using Wilcoxon rank-sum tests, and ipsilateral–contralateral paired analyses with Wilcoxon signed-rank and Sign tests at different PlaqueRADS thresholds. Results: Among 163 patients (CE=71, LAA=48, ESUS=44), ipsilateral PlaqueRADS ≥3 was more frequent in LAA (64.6%) and CE (45.07%) than in ESUS (27.3%). Ipsilateral scores were higher in LAA vs CE (p<0.001) and LAA vs ESUS (p<0.001), while ESUS vs CE did not differ (p=0.145). Within-etiology analyses showed ipsilateral enrichment in CE (p=0.0015) and LAA (p=0.004), but not in ESUS (p=0.97). In exploratory analyses of ESUS, no cutoff reached statistical significance; however, PlaqueRADS ≥4 occurred exclusively ipsilaterally (4/44 vs 0/44). Descriptive analysis of those 4 ESUS patients showed median age 71 years, universal smoking, 3/4 hypertensive, and preserved cardiac features, consistent with an atherothrombotic profile; however, one developed paroxysmal AF. During follow-up, 22% of ESUS patients developed new AF, and PFO prevalence remained higher than in CE/LAA despite exclusion of high-risk cases. Conclusion: LAA exhibits the highest ipsilateral PlaqueRADS burden, while CE patients also show non-negligible atherosclerotic findings. ESUS remains heterogeneous, overall resembling CE, but ~9% harbor unilateral high-risk PlaqueRADS (≥4), compatible with an atherothrombotic phenotype. Standardized PlaqueRADS scoring using VWI may refine ESUS classification and guide trial design by identifying patients less likely to benefit from anticoagulation over antiplatelet strategies. Validation in larger cohorts is warranted.