CMR Study Protocol:
All patients underwent a CMR study on a 1.5 Tesla clinical MR scanner (Ingenia, Philips Healthcare). CMR protocol included Cine MRI of LA and LV, and 3D late gadolinium enhancement (LGE) scan. Cine MRI was performed in axial plane for LA and short axis plane for LV using a retrospective ECG-gated balanced steady-state free precision (bSSFP) pulse sequence. Cine scan for LA covers the whole LA and LAA by a stack of contiguous 2D axial slices with thickness of 7.0 mm and spatial resolution of 1.56x1.74 mm. The other scan parameters for this Cine scan were repetition time (TR) = 2.80 ms, echo time (TE) = 1.40 ms, flip angle (FA) = 60o. Cine scan of LV covers the whole LV by a stack of 2D short-axis slices with thickness of 8.0 mm, inter-slice gap of 0.8 mm, spatial resolution of 1.45x1.65 mm. The other scan parameters for Cine of LV scan were TR = 3.48 ms, TE = 1.74 ms, FA = 90o. Scan protocol for 3D LGE was similar to 3D LGE protocol optimized and validated in DECAAF and DECAAF II multi-center studies (18). LGE scan was initiated 20-25 minutes after contrast agent administration using a 3D inversion recovery prepared, respiration navigated, ECG-gated, spoiled gradient echo pulse sequence. 3D LGE imaged axial slab covering LA and LAA with spatial resolution of 1.25x1.25x2.5 mm. The other scan parameters for 3D LGE were TR = 5.26 ms, TE = 2.58 ms, and FA = 20o.