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).