Age-, Sex-, and Race-Based Normal Values for Left Ventricular Circumferential Strain from the World Alliance Societies of Echocardiography Study

Abstract

Left ventricular (LV) circumferential strain has received less attention than longitudinal deformation, which has recently become part of routine clinical practice. Among other reasons, this is because of the lack of established normal values. Accordingly, we aimed to establish normative values for LV circumferential strain and determine sex-, age- and race-related differences in a large cohort of healthy adults. Complete 2D transthoracic echocardiograms were obtained in 1572 healthy subjects (51% male), enrolled in the World Alliance of Societies of Echocardiography (WASE) Study. Subjects were divided into 3 age groups (<35, 35-55, >55 years) and stratified by sex and by race. Vendor-independent semi-automated speckle tracking software was used to determine LV regional and global circumferential strain (GCS) values. Limits of normal for each measurement were defined as 95% of the corresponding sex and age group falling between the 2.5th and 97.5th percentiles. Intergroup differences were analyzed using unpaired t-tests. Circumferential strain showed a gradient, with lower magnitude at the mitral valve level, increasing progressively towards the apex. Compared to men, women had statistically higher magnitude of regional and global strain. Older age was associated with a stepwise increase in GCS despite an unaffected EF, a decrease in LV volume and a relatively stable GLS in men with a small gradual decrease in women. Asian subjects demonstrated significantly higher GCS magnitudes than whites of both sexes and blacks in women only. In contrast, no significant differences in GCS were found between white and black subjects of either sex. Importantly, despite statistical significance of the above differences across sex-, age- and races, circumferential strain values were similar in all groups, with variations of the order of magnitude of 1-2%. Notably, no differences in GCS were found between brands of imaging equipment. This study established normal values of LV regional and global circumferential strain, and identified sex-, age- and race-related differences, where present.