Left Atrial Strain Determinants During the Cardiac Phases

The present study investigated the determinants of left atrial (LA) strain in all phases of the cardiac cycle.

LA strain by speckle-tracking echocardiography allows the assessment of LA function in each phase of the cardiac cycle. However, its determinants and its relation with left ventricular (LV) function have not yet been fully described.

The authors performed a retrospective analysis in 127 patients with different cardiovascular pathologies. Using 2-dimensional speckle tracking in 4- and 2-chamber apical views we derived both LA and LV strain curves. Strain-strain loops were reconstructed using LV strain and the corresponding, synchronized LA strain data. Linear regressions were calculated for the entire strain-strain loop as well as for the 3 phases of the cardiac cycle (systole, and early and late diastole). The association between LA strain parameters and LV systolic and diastolic parameters was studied. The prediction of cardiovascular events was evaluated for both measured and predicted LA strain and other parameters.

LA and LV strain curves presented excellent correlations with an R² > 0.90 for the cardiac cycle, and R² > 0.97 for its phases. Moreover, the ratios of LV/LA maximal volumes and the slopes of the LA-LV strain-strain loops of the individual patients correlated well (R² = 0.75). In each phase of the cardiac cycle, LA strain parameters correlated well with the corresponding LV strain and the LV-LA volume ratio (R² > 0.78). No significant difference in predictive ability of cardiovascular events or atrial fibrillation between the measured and predicted LA strain was observed (P > 0.05 for both).

In the absence of abnormal LA/LV volume exchange, LA strain is, to a large extent, determined by LV strain and further modulated by the ratio of LV and LA volumes. Nonetheless, measuring LA strain is of high clinical interest because it integrates several parameters into a single, robust, and reproducible measurement.