Left ventricular twist in a normal African adult population

Speckle tracking has emerged as a quantitative technique for assessing left ventricular (LV) function. However, no normative data for LV twist using speckle tracking echocardiography (STE) are available in the black population. This study assessed myocardial mechanics by determining LV twist parameters in different age groups using STE, and evaluated the effect of ageing on LV twist in this population.

The study population consisted of 127 healthy volunteers divided into four age groups: 20-29 (n = 34); 30-39 (n = 33); 40-49 (n = 29); and 50-65 (n = 31) years. Parasternal short-axis images of three consecutive end-expiratory cardiac cycles at LV basal, papillary muscle, and apical levels, and apical four-chamber images were obtained. Apical and (AR) basal (BR) LV peak systolic rotation during ejection and instantaneous LV peak systolic twist (net twist, defined as maximal value of instantaneous AR minus BR) were measured. Mean strain values were -17.28 ± 3.30% for longitudinal, -17.40 ± 3.29% for circumferential, and 57.49 ± 3.32% for radial strain. Mean rotational values were AR (5.56 ± 1.98°), BR (-3.31 ± 0.92°), and net twist (8.87 ± 2.21°). AR, BR, and net twist increased with age, whereas longitudinal, circumferential, and radial strain decreased with age. Multivariate linear regression analysis showed age as the main predictor of net twist (R(2) = 0.82, P < 0.0001).

These data establish values for strain and twist in a normal black adult population. Net twist increases with age, whereas strain parameters decrease. Age is the strongest independent predictor of LV twist.