Echocardiographic reference ranges for normal left ventricular 2D strain: results from the EACVI NORRE study

TLDR: The NORRE study provides contemporary, applicable 2D echocardiographic reference ranges for LV longitudinal, radial, and circumferential strain and highlights the importance of age- and gender-specific reference values for LV strain.

Abstract: Aims - To obtain the normal ranges for 2D echocardiographic (2DE) measurements of left ventricular (LV) strain from a large group of healthy volunteers accounting for age and gender. Methods and results - A total of 549 (mean age: 45.6 ± 13.3 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. 2DE data sets have been analysed with a vendor-independent software package allowing homogeneous measurements irrespective of the echocardiographic equipment used to acquire the data sets. The lowest expected values of LV strains and twist calculated as ± 1.96 standard deviations from the mean were -16.7% in men and -17.8% in women for longitudinal strain, -22.3% and -23.6% for circumferential strain, 20.6% and 21.5% for radial strain, and 2.2 degrees and 1.9 degrees for twist, respectively. In multivariable analysis, longitudinal strain decreased with age whereas the opposite occurred with circumferential and radial strain. Male gender was associated with lower strain for longitudinal, circumferential, and radial strain. Inter-vendor differences were observed for circumferential and radial strain despite the use of vendor-independent software. Importantly, no intervendor differences were noted in longitudinal strain. Conclusion - The NORRE study provides contemporary, applicable 2D echocardiographic reference ranges for LV longitudinal, radial, and circumferential strain. Our data highlight the importance of age- and gender-specific reference values for LV strain.