EXPRESS: Neutral lipids in Thrombectomy-retrieved clots: Histological link to Stroke Severity, Etiology and 3-Months Functional Outcome

BACKGROUND/HYPOTHESIS: Analysis of stroke thrombi collected during catheter-based recanalization offers a promising approach to refine etiological classification and guide treatment, as it provides pathophysiological insights through clot structure and composition. Despite the established role of lipids in large artery atherosclerotic stroke, their presence in stroke thrombi has not yet been studied histologically. METHODS: In a prospective single-center cohort, neutral lipids were analysed by Oil Red O staining in 145 consecutively collected clots between 07/2020 and 08/2022, and lipid content was subsequently quantified using Orbit Image analysis. Clinical, laboratory and neuroradiological data were recorded. Functional outcome was assessed by modified Rankin Scale at 3 months. RESULTS: Of 135 evaluable clots, 25 (19%) contained neutral lipids, present as lipid droplets, scattered deposits or foam-cell like configurations. Lipid-positive thrombi contained more fibrin, and patients with lipid-positive thrombi had greater stroke severity and worse functional outcome. Lipid positivity was independently associated with undetermined rather than cardioembolic stroke etiology after adjustment for fibrin content. CONCLUSIONS: This is the first study to histologically identify neutral lipids within clots retrieved from acute ischemic stroke patients. Thrombus lipid content was associated with worse functional outcomes and may provide additional information on the underlying etiology of otherwise undetermined stroke.