Echocardiographic reference ranges for normal non-invasive myocardial work indices: results from the eacvi norre study

Background: Myocardial work (MW) is a parameter of myocardial function, which takes into account deformation as well as afterload. Left ventricle (LV) pressure­strain loops (PSLs) are a novel and reliable tool for the non­invasive assessment of MW. Purpose: the aim of this study was to obtain normal ranges for 2D echocardiographic indices of MW from a large group of healthy volunteers according to age and gender. Methods: A total of 226 (mean age: 44.7±13.2 years) healthy subjects were enrolled at 22 collaborating institutions of the Normal Reference Ranges for Echocardiography (NORRE) study. Global Work Index (GWI), Global Constructive Work (GCW), Global Work Waste (GWW) and Global Work Efficiency (GWE) were estimated by LV PSLs using custom software (Figure). Peak LV pressure was estimated non­invasively from brachial artery cuff pressure. Results: The lowest expected values of MW indices calculated as ± 1.96 standard deviation from the mean were 1270.4 mmHg% in men and 1310.3mmHg% in women for GWI, 1649.7 mmHg% and 1543.5 mmHg% for GCW, ­2.6 mmHg% and 16.6 mmHg% GWW, and 90.7% and 91.7% for GWE, respectively. Hence, male subjects had lower values of GWE and higher values of GWW. GWI and GCW significantly increased with age in female patients. Conclusions: The NORRE study provides useful 2D echocardiographic reference ranges for novel indices of non­invasive MW.