Left Atrial Strain as a Predictor of Cardiac Dysfunction in a Murine Model of Pressure Overload

Aim: Left atrial (LA) strain is emerging as a valuable metric for evaluating cardiac function, particularly under pathological conditions such as pressure overload. This preclinical study investigates the predictive utility of LA strain on cardiac function in a murine model subjected to pressure overload, mimicking pathologies such as hypertension and aortic stenosis. Methods: High resolution ultrasound was performed in a cohort of mice (n=16) to evaluate left atrial and left ventricular function at baseline and 2- and 4-weeks after transverse aortic constriction (TAC). Acute adaptations in cardiac function were assessed in a subgroup of mice (n=10) with 3-days post TAC imaging. Results: We report an increase in LA max volume from 11.0 plus-or-minus sign 4.3lower case Greek muL at baseline to 26.7 plus-or-minus sign 16.7lower case Greek muL at 4 weeks (p=0.002) and a decrease in LA strain from 19.6 plus-or-minus sign 4.8% at baseline to 10.1 plus-or-minus sign 6.3% at 4 weeks (p=0.006). In the acute phase, LA strain dysfunction was present at 3-days (p<0.001) prior to alterations in LA volume (p=0.856) or left ventricular (LV) ejection fraction (p=0.120). LA strain correlated with key indicators of cardiac performance including left ventricular (LV) ejection fraction (r=0.563, p<0.001), longitudinal strain (r=-0.643, p<0.001) and strain rate (r=0.387, p=0.007). Furthermore, markers of atrial structure and function including LA max volume (AUC=0.858, p<0.001), ejection fraction (AUC=0.901 p<0.001), and strain (AUC=0.878, p<0.001) all predicted LV dysfunction. Conclusion: LA strain and function assessments provide a reliable, non-invasive method for early detection and prediction of cardiac dysfunction in a model of pressure overload.