366 The use of dedicated long-axis views focused on the left atrium improves the accuracy of left atrial volumes and function measured by cardiovascular magnetic resonance

Aims The use of apical views focused on the left atrium (LA) has improved the accuracy of LA volume evaluation by two-dimensional echocardiography. However, routine cardiac magnetic resonance (CMR) evaluation of LA volumes still uses standard 2- and 4-chamber cine images focused on the left ventricle. To investigate the potential of LA-focused CMR cine images, we compared LA maximal (LAVmax) and minimal (LAVmin) volumes, and emptying fraction (LA-EF) calculated on both standard and LA-focused long-axis cine images with LA volumes obtained by short-axis cine stacks covering the LA. Methods and results LA volumes and LA-EF were obtained from 108 consecutive patients by applying the biplane area-length algorithm to both standard and LA-focused 2- and 4-chamber cine images. Manual segmentation of a short-axis cine stack covering the LA was used as the reference method. Compared to the reference method, the standard approach significantly underestimated LA volumes (LAVmax: bias −13 ml; LOA = +11 ml, −37 ml; LAVmin; bias −10 ml, LOA: +9 ml, −28ml), and overestimated LA-EF (bias= 5%, LOA: +23%, −14%). Conversely, LA volumes (LAVmax bias −0.03 ml; LOA: +10 ml, −10 ml. LAVmin bias = −1.5 ml; LOA: +7 ml, −10 ml), and LA-EF (bias 2%, LOA: +11%, −7%) by LA-focused cine images were similar to those measured using the reference method. Moreover, LA volumes by LA-focused images were obtained faster than using the reference method (1.2 vs. 4.5 min, P < 0.001). Conclusions LA volumes and LA-EF measured using dedicated LA-focused long-axis cine imaging are more accurate than using standard (LV-focused) cine images.