Left Atrial Size Assessment
LA diameter was assessed with a pre-procedural transthoracic echocardiography (TTE; n = 256), when available. LA diameter > 4 cm on TTE was defined as enlarged based on the American Society of Echocardiography guidelines (3). LA volume was measured using pre-procedural contrast-enhanced cardiac computed tomographic (CT) imaging (n = 236), when available. CT images were obtained using a 320-detector scanner (Aquilion ONE, Canon Medical Systems) and prospective scan acquisition targeted at 40% of the R-R cycle (end-systole) without padding. Images were reconstructed with a slice thickness of 1 mm and soft reconstruction kernel (FC03) and then transferred to a commercially available image workstation (Vitrea, Vital Images, Minneapolis, MN, USA) for analysis. The software includes a cardiac chamber volume analysis algorithm, which allows automated tracing of the contrast enhanced left atrial cross-sectional border contours and computes volume by interpolating the vertical increments of 1 mm for the structure’s cranio-caudal extension. The algorithm truncates borders in the proximal portion of the pulmonary veins and includes the left atrial appendage for volumetric assessment. Indexed volumes were calculated by dividing the volumes by body surface area and recorded as LA volume index (LAVi).