Normal Values for Echocardiographic Myocardial Work in a Large Pediatric Population

Background: Echocardiographic myocardial work is a new load-independent echocardiographic technique to quantify left ventricle (LV) systolic performance. Our aim was to establish normal values for echocardiographic myocardial work in a large population of healthy children. Methods: For all the subjects 4-, 2-, and 3-chamber-view videos were stored. The following parameters were obtained by offline analysis: the global myocardial work (GMW), the global myocardial constructive work (GCW), the global myocardial wasted work (GWW), and the global myocardial work efficiency (GWE). Age, weight, height, heart rate, and body surface area (BSA) were used as independent variables in the statistical analysis. Results: In all, 516 healthy subjects (age range, 1 day-18 years; median age, 8.2 +/- 5.3 years; 55.8% male; body surface area (BSA) range, 0.16 to 2.12 m(2)) were included. GWI, GCW, and GWW increased with weight, height, and BSA (rho ranging from 0.635 to 0.226, p all < 0.01); GWI and GCW positively correlated with age (rho 0.653 and 0.507). After adjusting for BSA differences, females showed higher mean GWI (p = 0.002) and GCW values (p < 0.001), thus Z-score equations for gender have been presented. Conclusions: We provided MW values in a large population of healthy pediatric subjects including lower ages. MW values increased with age and body size and, interestingly, were higher in females than in men. These data cover a gap in current nomograms and may serve as a baseline for the evaluation of MW analysis in children with congenital and acquired heart diseases.