Aims: Strain and strain rate (SR) are measures of deformation that reflect left ventricular (LV) function. To our knowledge, no previous study described these indexes in a general population. We therefore described peak-systolic strain and SR of the LV in the general population and derived diagnostic thresholds for these measurements in a healthy subgroup.
Methods and results: In 480 subjects enrolled in a family-based population study (50.5% women; mean age, 50.5 years; 37.2% hypertensive), we measured: (i) end-systolic longitudinal strain and peak-systolic SR from the basal portion of the LV inferior and inferolateral free walls; (ii) radial deformation of the LV inferolateral wall. Longitudinal (mean, 22.9%) and radial (59.2%) strain and longitudinal (1.31 s(-1)) and radial (3.40 s(-1)) SR decreased with age (P </= 0.007). Longitudinal and radial strain independently decreased (P </= 0.006) with relative wall thickness (RWT), longitudinal strain with the waist-to-hip ratio, and radial strain with body weight. In contrast, LV ejection fraction increased (P </= 0.0001) with age and RWT. Longitudinal and radial stain rate increased with heart rate (P </= 0.05). In healthy subgroup (n = 236), the fifth percentiles were 18.4 and 44.3%, and 0.99 and 2.43 s(-1), for longitudinal and radial strain and SR, respectively.
Conclusion: We explored the early signs of LV systolic dysfunction in a general population, using tissue Doppler imaging technique. LV strain and SR decrease with age, body weight, central obesity, and RWT. Our current study resulted in the proposal for diagnostic thresholds for strain and SR, based on a healthy subgroup recruited via random sampling of the population.