Quantitative CTA-Based Carotid Plaque Composition Across Stroke Etiologies and Residual Vascular Risk

Background: Carotid plaque vulnerability features may provide prognostic information beyond luminal stenosis, but the value of quantitative plaque composition on CTA remains unclear. Objectives: We investigated whether plaque composition analysis in routine CTA in patients with ischemic stroke or TIA can identify high-risk plaques across etiologies, particularly among strokes of undetermined etiology and predict residual vascular risk. Methods: We analyzed carotid CTAs from 314 patients with acute ischemic stroke or TIA. CTA-derived plaque composition was quantified using commercially available software and compared between ipsilateral and contralateral plaques across etiology groups. Associations of plaque characteristics with subsequent vascular events were assessed using Cox regression models. Results: Among patients with ischemic events of undetermined etiology, ipsilateral plaques showed significant enrichment for greater LRNC volume (ratio, 1.97; 95% CI, 1.22-3.18), an association that persisted after adjustment for wall volume (ratio, 1.51; 95% CI, 1.15-1.99). During a median 3-year follow-up, larger LRNC volume was associated with subsequent vascular events in patients with ischemic stroke of undetermined etiology (HR, 1.96; 95% CI, 1.12-3.43), as were calcification, noncalcified matrix, and total wall volumes. Associations for individual plaque components attenuated after adjustment for wall volume. Conclusions: CTA-derived LRNC is enriched in carotid plaques ipsilateral to ischemic events of undetermined etiology and is associated with future vascular risk. Quantitative CTA-based plaque assessment may provide complementary information for etiologic evaluation and vascular risk stratification.