Echocardiographic Reference Ranges of Non-invasive Myocardial Work Indices in Children

Global myocardial work (GMW) is an emerging method to characterize left ventricle (LV) function with potential advantages over both ejection fraction and global longitudinal strain (GLS). We aimed to determine the feasibility and reproducibility for echocardiographic-derived GMW in a healthy pediatric population; establish normal reference values; and investigate the influence of age, gender, and other clinical factor on normal reference ranges. We prospectively enrolled 212 individuals (median age of 9 years; interquartile range, 6 to 12 years, 112 female). Global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE) were measured from LV pressure-strain loops. Quantification of GMW was performed using a GE Vivid E95 system and available software package (Echopac V.203, GE). The mean LV EF was 64 ± 3% with GLS of -21.3 ± 1.5%. GWI was 1688 ± 219 mmHg% with mean GWE of 96.5 ± 1.4%. The GCW was 1959 ± 207 mmHg%, and the mean GWW of 61.1 ± 30.9 mmHg%. No significant difference was found in MW indices across age group and gender (p > 0.05 for all). There were significant correlations between both GWI and GCW with GLS and systolic blood pressure (p < 0.001), but not with GWE and GWW. Linear regression model revealed that GWI and GCW were more closely correlated with systolic blood pressure than GLS. LV MW indices had good intra-observer and inter-observer reproducibility. This study establishes both the feasibility and reference ranges for non-invasive echocardiographic indices of GMW in healthy children. Myocardial work appears to be a complementary modality to assess LV performance in children.