Understanding the role of the left atrial appendage on the flow in the atrium.

BACKGROUND: The exclusion/occlusion of the left atrial appendage (LAA) is a treatment option for atrial fibrillation (AF) patients who are at high risk of stroke and high risk of bleeding. As the role of the LAA is not well understood or explored, this study aims to assess its role on flow dynamics in the left atrium. METHODS: Computational fluid dynamics (CFD) simulations were carried out for nine AF patients before and after LAA exclusion. The flow parameters investigated included the LA velocities, Time Averaged Wall Shear Stress (TAWSS), Oscillatory Shear Index (OSI), Relative Residence Time (RRT), and Pressure in the LA. RESULTS: This study shows that, on average, a decrease in TAWSS (1.82 ± 1.85 Pa to 1.27 ± 0.96 Pa, p < 0.05) and a slight increase in OSI (0.16 ± 0.10 to 0.17 ± 0.10, p < 0.05), RRT (1.87 ± 1.84 Pa-1 to 2.11 ± 1.78 Pa-1, p < 0.05), and pressure (-19.2 ± 6.8 mmHg to -15.3 ± 8.3 mmHg, p < 0.05) were observed in the LA after the exclusion of the LAA, with a decrease in low-magnitude velocities. CONCLUSION: The exclusion of the LAA seems to be associated with changes in LA flow dynamics. Further studies are needed to elucidate the clinical implications of these changes.

Cardiac computed tomography following Watchman FLX implantation: device-related thrombus or device healing?

AIMS: Cardiac computed tomography (CT) is increasingly utilized during follow-up after left atrial appendage closure (LAAC). Hypoattenuated thickening (HAT) is a common finding and might represent either benign device healing or device-related thrombosis (DRT). The appearance and characteristics of HAT associated with the Watchman FLX have not been previously described. Therefore, we sought to investigate cardiac CT findings during follow-up after Watchman FLX implantation with a focus on HAT and DRT. METHODS AND RESULTS: Retrospective single-centre, observational study including all patients with successful Watchman FLX implantation and follow-up cardiac CT between March 2019 and September 2021 (n = 244). Blinded analysis of CT images was performed describing the localization, extent, and morphology of HAT and correlated to imaging and histology findings in a canine model. Relevant clinical and preclinical ethical approvals were obtained.Overall, HAT was present in 156 cases (64%) and could be classified as either subfabric hypoattenuation (n = 59), flat sessile HAT (n = 78), protruding sessile HAT (n = 16), or pedunculated HAT (n = 3). All cases of pedunculated HAT and five cases of protruding sessile HAT were considered as high-grade HAT (n = 7). Subfabric hypoattenuation and flat sessile HAT correlated with device healing and endothelialization in histological analysis of explanted devices. CONCLUSION: Subfabric hypoattenuation and flat sessile HAT are frequent CT findings for Watchman FLX, likely representing benign device healing and endothelialization. Pedunculated HAT and protruding HAT are infrequent CT findings that might represent DRT.

Left atrial appendage occlusion in haemophilia patients with atrial fibrillation.

PURPOSE: Advanced targeted therapy has resulted in increasing life expectancy and incidence of age-related cardiovascular diseases like atrial fibrillation in patients with haemophilia. Oral anticoagulation constitutes a significant dilemma in this patient category as the risks of stroke and bleeding are difficult to balance. We sought to demonstrate the feasibility of left atrial appendage occlusion (LAAO) in patients with haemophilia and atrial fibrillation. METHODS: All patients with haemophilia treated with LAAO at Aarhus University Hospital, Denmark, were identified from a local prospective database comprising all consecutive LAAO procedures from 2010 up to November 2020. Based on review of the medical records, a retrospective descriptive analysis was performed. RESULTS: Seven patients with haemophilia A and atrial fibrillation underwent LAAO after multidisciplinary conference. Peri-procedural coagulation management was guided by factor VIII activity and treated with repeated bolus administrations of recombinant factor VIII targeting an activity of 100%. The implantation was successful in all patients with only minor bleeding complications post-procedurally. Based on these experiences, a suggested regime has been formulated. CONCLUSIONS: LAAO is feasible in haemophilia patients with concurrent atrial fibrillation. However, special care including intravenous substitution with coagulation factors must be given in the periprocedural management.