Abstract 12615: Slow and Oscillatory Blood-Flow in the Left Atrial Appendage is Associated With Stroke Risk in Atrial Fibrillation Patients

Abstract

Introduction: Atrial fibrillation (AF) patients are at high risk of stroke with ~90% clots originating from the left atrial appendage (LAA). Studies correlating left atrial (LA) and LAA geometrical parameters with stroke exhibit conflicting results. Also, blood-flow based parameters and their association with stroke for AF patients remains unexplored. Hypothesis: Low blood-flow in the LA/LAA is associated with stroke for AF patients. Methods: We retrospectively collected CT images of 53 AF patients and dichotomized them based on clinical event into stroke and non-stroke groups. After image segmentation to obtain 3D LA geometry, personalized blood-flow analysis was performed to model LA hemodynamics. For geometry, we calculated area of 4 pulmonary veins (PVs) and area and volume of LA/LAA. For hemodynamics, we quantified blood flow velocity, wall shear stress (WSS, blood-friction on LA wall), oscillatory shear index (OSI, directional change of WSS) and endothelial cell activation potential (ECAP, ratio of OSI and WSS quantifying slow and oscillatory flow) in LA/LAA. All parameters were compared between the groups. Results: Twenty-seven patients were included in the stroke and 26 in the non-stroke group. Geometrically, there was non-significant difference between the LA/LAA area and volume, and area of PVs between the groups (Figure A). In terms of blood-flow (Figure B), velocity, WSS, OSI and ECAP in the LA had non-significant differences between the groups. However, stroke group had significantly lower velocity, WSS and higher ECAP in LAA as compared to non-stroke group. This suggests that stroke patients had slow and oscillatory circulating blood-flow in the LAA, exposing it to thrombogenesis, potentially causing stroke. Conclusion: Slow and oscillatory flow in the LAA alone is associated with stroke in this AF cohort. Personalized blood-flow analysis can identify such hemodynamic conditions, aiding in clinical stroke risk stratification of AF patients.