Abstract 15619: Personalized Assessment of Stroke Risk in AF Patients Undergoing Left Atrial Appendage Closure Using Blood-flow Analysis

Abstract

Introduction: Left atrial appendage (LAA) is the primary source of clot formation that can cause stroke or transient ischemic attack (TIA) in patients with atrial fibrillation (AF). LAA closure devices have emerged as alternatives to traditional anticoagulation therapy for reducing stroke risk in AF patients. However, ~1-2% of AF patients undergoing LAA closure have subsequent stroke/TIA event. Hypothesis: The presence of a persistent low-flow zone in LA, distinct from LAA, explains why some patients have stroke/TIA events after LAA closure. Methods: We developed a personalized stroke risk prediction tool that uses patient’s CT image to perform computational fluid dynamics simulation and determine presence of low blood-flow in the LA before and after LAA closure. Low flow is quantified by the establishment of low velocity fraction (LVF) in the LA volume, and low wall shear stress fraction (LWSSF) on the surface of the LA wall. The tool was applied retrospectively on 4 AF patients who had undergone LAA closure: 2 patients with TIA 4 months after LAA closure, and 2 controls matched for age, gender, CHA2DS2-VASc score and LAA dimensions with no complications at follow-up up to 2 years. Results: Before LAA closure, TIA and control groups had similar LVF (0.07 and 0.06, respectively) and LWSSF (0.12 and 0.16, respectively). However, after LAA closure, the TIA group had smaller reductions as compared to controls in both LVF (67% vs 79%) and LWSSF (17% vs 52%). This suggests that the LA low-flow region (especially at LA wall) was not substantially reduced after LAA closure, explaining why these patients might have experienced TIA. Conclusion: This proof-of-concept study demonstrates that LAA closure might not substantially reduce low-flow zones for all AF patients, as some retain low-flow zones in LA. Our stroke prediction tool has the potential to identify patients at risk of future stroke/TIA, thus enabling personalized patient selection to increase efficacy of LAA closure devices.