Background: Although two-dimensional speckle tracking (2DST) has been validated in animal and early clinical studies for quantitative evaluation of myocardial motion and contractility, there are only limited measurements in large healthy population to be used as reference data, which severely restricts its clinical application. This study aimed at determining the age-specific normal values of left ventricular (LV) longitudinal, circumferential and radial strain in healthy adults.
Methods: We studied 228 healthy subjects (109 males, mean age 44 ± 15 years, range 18-78 years). Their LV longitudinal, circumferential and radial strains were measured by 2DST at basal, middle and apical levels of parasternal short-axis and apical 2-, 4- and 3-chamber views. The effects of age, gender and echocardiographic machines (52 patients had measurements obtained by both GE and Philips machines) on these parameters were also evaluated.
Results: The longitudinal and circumferential strains were -20.4 ± 3.4% and -22.9 ± 3.1%, respectively with higher values being observed at basal than apical segments. On the contrary, the radial strain which ranged 42.6 ± 12.9% decreased towards apical segments. The longitudinal strain declined, the circumferential strain rose and the radial strain remained similar during aging. Adult females had slightly higher circumferential and longitudinal strains than males (23 ± 3% vs -22 ± 3%, -21 ± 3% vs -20 ± 3% respectively; both p<0.01). Strains measured by the 2 different echo machines had good correlations but Phillips-assessed strains (longitudinal and circumferential) were 10% higher than GE measurements. Inter- and intra-observer variabilities were acceptable.
Conclusions: Strain measurements by 2DST echocardiography varies with age, gender and echocardiographic vendors in healthy adults. These findings are important to differentiate between health and disease and to assess the severity of disease.
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