Left atrial appendage shape impacts on the left atrial flow hemodynamics: A numerical hypothesis generating study on two cases

•3D-dimensional simulation of blood flow inside LA with/out LAA was carried out for two different patients.•Patient 1 had one lobe appendage, and patient 2 had two-lobes.•LAA removal in patients led to unassuming results due to LAA shape and volume.•LAA removal in patient 2 caused a reduction in velocity and vorticity.•For patient 1 with two lobes appendage, LAA removal had more complicated effects.•In AF condition, two lobes appendage is more likely to have a thrombus inside LAA.•Impacts of LAA removal were more dominant under AF.