Normal values for left atrial strain, volume and function derived from three-dimensional echocardiography in the general population

Abstract Background Three-dimensional echocardiographic (3DE) assessment of the left atrium (LA) is a new modality of potential clinical value. Age- and sex-based normative values are needed to benchmark these parameters for clinical use. Methods The study included 4,466 participants from a prospective longitudinal cohort study in the general population, among these 2,082 participants underwent 3DE of the LA. Exclusion criteria were hypertension, diabetes, ischemic heart disease, history of stroke, atrial fibrillation, heart failure, use of heart medication, chronic kidney disease, use of pacemaker, significant valve regurgitation or valve stenosis. Healthy participants were included to establish normative values for LA strain, volume, and function by 3DE. The effects of age and sex on 3DE parameters were also evaluated. Mean volumes per second for included participants was 62.4±5.7. Results After excluding participants with comorbidities, the final study population constituted of 979 healthy participants, median age was 44 years (interquartile range 32-56 years), 40% men. The median and limits of normality (2.5th and 97.5th percentiles) for functional and volumetric measures were: LA reservoir strain (LASr) 30.8% (18.4-44.2%), LA conduit strain (LAScd) 19.1% (6.8-32.0%), LA contractile strain (LASct) 11.7% (4.3-22.2%) (Figure 1) total LA emptying fraction (LAEF) 61.4% (47.8-71.0%), passive LAEF 37.7% (17.4-53.9%), active LAEF 37.4% (22.2-52.5%), LA minimum volume index (LAVimin) 10.2 (5.9-18.5) ml/m2, and LA maximum volume index (LAVimax) 26.8 (16.5-40.1) ml/m2 (Figure 2). All parameters changed significantly with increasing age (p value for all <0.001). Significant sex-specific differences were observed for all parameters except for active LAEF. Sex significantly modified the association between age and LASr (p for interaction<0.001), LAScd (p for interaction<0.001), LAVimin (p for interaction=0.037), and total LAEF (p for interaction=0.034). Conclusion We present age- and sex specific reference material including limits of normality for LA strain, volume, and function by 3DE.