Abstract 39: Slow-Flow in the Left Atrial Appendage on Cardiac CT in Patients With Acute Ischemic Stroke

Abstract

Background: Slow-flow in the left atrial appendage (LAA) is thought to be associated with an increased risk of thrombus formation and stroke. We studied LAA slow-flow on cardiac CT in patients with acute ischemic stroke (AIS). Method: We used data from Mind the Heart, a prospective cohort study of AIS patients who underwent ECG-gated cardiac CT during the acute imaging protocol. We compared baseline characteristics, functional outcome (modified Rankin scale), stroke recurrence and major adverse cardiovascular events (MACE) after 2-year follow-up between patients with LAA thrombus (filling defect <100 Hounsfield Unit [HU]), slow-flow (filling defect, but with ≥100 HU) and normal filling. We performed a sensitivity analysis restricted to cryptogenic stroke patients. Results: Of 421 patients, 31 (7%) were classified as LAA thrombus, 69 (16%) as LAA slow-flow and 321 (76%) as normal LAA filling. Patients with LAA thrombus or slow-flow more often had atrial fibrillation compared to normal filling (45%, 39%, 9%, p<0.001, respectively). LAA thrombus patients had more severe strokes compared to slow-flow and normal filling (NIHSS 18 [IQR: 9-22], 6 [IQR: 3-17], 5 [IQR: 2-11], p<0.001). There was no significant difference between LAA slow-flow patients and normal LAA filling in functional outcome (acOR: 0.8, 95%CI 0.5-1.4), recurrent ischemic stroke (aHR 0.8, 95%CI: 0.3-1.9) or MACE (aHR 1.2, 95%CI 0.7-2.1). In cryptogenic stroke patients (n=156), LAA slow-flow was associated with a higher risk of recurrent stroke (aHR: 4.1, 95%CI: 1.1-15.7) compared to normal LAA filling (Figure 1). Conclusion: Patients with LAA slow-flow had similar characteristics compared to patients with a thrombus, including high rates of atrial fibrillation, but had less severe strokes. Compared to patients with normal filling, LAA slow-flow was not significantly associated with worse functional outcome or MACE, but was associated with recurrent stroke in patients with cryptogenic stroke.