Left atrium
The endocardial border of the left atrium (LA) was traced in the apical 4-chamber view, excluding the appendage and pulmonary veins from the LA cavity. We acquired 3-5 consecutive, regular beats. The region of interest (ROI) started delineating the endocardial border from de mitral annulus on one side and ends at the mitral annulus on the opposite side. A ROI of 3 mm was used. Accuracy of the automated border tracking was verified and manually adjusted if needed. LA longitudinal strain curves were generated throughout the cardiac cycle with R-R gating. LA stretches its walls during LV systole and for this reason, LA longitudinal deformation is usually expressed with positive values. The LA reservoir in systole, conduit in early diastole and contraction strain in late diastole were measured. The normal value of reservoir strain was 39% and the contraction strain 18%. The conduit strain was obtained with the following formula: Reservoir strain – Contraction strain. Decreased LA-GS and LA reservoir function was considered to be present when it was <39%, as previously reported (Figure 2B) (13).