Determinants and Regression Equations for the Calculation of z Scores of Left Ventricular Tissue Doppler Longitudinal Indexes in a Healthy Italian Pediatric Population

Abstract

Aim. We investigated the predictors of tissue Doppler left ventricular (LV) longitudinal indexes in a healthy Italian pediatric population and established normative data and regression equations for the calculation of z scores. Methods and Results. A total of 369 healthy subjects aged 1-17 years (age of 6.4 ± 1.1 years, 49.1% female) underwent echocardiography. LV peak longitudinal velocity at systole (s'), early diastole (e'), and late diastole (a') was determined by tissue Doppler. The ratio of peak early diastolic LV filling velocity to e' was calculated. Age was the only independent determinant of s' (β=0.491, p<0.0001) and the strongest determinant of e' (β=0.334, p<0.0001) and E/e' (β=-0.369, p<0.0001). Heart rate was the main determinant of a' (β=0.265, p<0.0001). Male gender showed no effects except for a weak association with lateral s', suggesting no need of gender-specific reference ranges. Age-specific reference ranges, regression equations, and scatterplots for the calculation of z scores were determined for each index. Conclusion. In a pediatric Italian population, age was the strongest determinant of LV longitudinal dynamics. The availability of age-specific normality data for the calculation of z scores may allow for correctly detecting LV dysfunction in pediatric pathological populations.