Non-invasive left ventricular myocardial work indices in healthy adolescents at rest

Global myocardial work (GMW) provides a metric of left ventricular (LV) function and energy consumption. Its non-invasive assessment by echocardiography correlates with invasive measures and normal values have been reported in healthy adults. We aimed to establish normal values in a healthy adolescent population. Fifty-two healthy adolescents (mean age = 14.5 ± 2.0 years, range 11-19 years, 62% male) with normal echocardiograms were included. Brachial cuff blood pressure was obtained immediately following apical imaging in the supine position. Post-processing of echocardiograms for speckle tracking strain measurement and derivation of global myocardial work indices from LV pressure-strain loops was performed. The mean global work index (GWI) was 1802.0 ± 264.4 mmHg% with mean global work efficiency of 95.5 ± 1.1%. The mean global constructive work (GCW) was 2054.5 ± 297.3 mmHg%, and the mean global wasted work 83.8 ± 28.1 mmHg%. On multivariable analysis, there were significant associations between both GWI and GCW with systolic blood pressure (β coefficient = 0.57, p < 0.001; β coefficient = 0.67, p < 0.001 respectively) and LV global longitudinal strain (GLS) (β coefficient = - 0.56, p < 0.001; β coefficient = - 0.52, p < 0.001 respectively). There were no associations with any of the work indices with age, sex, body surface area, heart rate or LV ejection fraction. This study provides echocardiographic reference ranges for non-invasive indices of GMW in normal adolescents.