P655Three-dimensional morphology and mechanics of the left ventricle and the left atrium in adolescent athletes

Abstract

Regular physical exercise results in complex morphological and functional remodelling of the left ventricle (LV) and also the left atrium (LA), however, conventional echocardiographic parameters offer limited power to assess subtle features of athlete's heart compared to non-trained individuals. Three-dimensional (3D) echocardiography may overcome these limitations enabling an accurate volumetric quantification and mechanical characterization of both the LV and the LA. Accordingly, our aim was to characterize exercise-related adaptation of the LV and the LA in adolescent athletes using 3D echocardiography. Fifty adolescent male soccer players (16±1 years, 10 hours training/week in average) were enrolled and compared to 20 age-matched sedentary male volunteers. Full volume 3D datasets reconstructed from 4 or 6 cardiac cycles, focused on the LV and the LA were acquired. Using dedicated 3D software (TomTec 4D LVAnalysis with prototype LA option) to contour and track the endocardial border of the LV and the LA, we have determined LV end-diastolic volume (LVEDV), LV ejection fraction (LVEF), LA volume (LAV), LA ejection fraction (LAEF) and LA passive and active ejection fraction (active EF, passive EF). By speckle-tracking analysis of the 3D models, we quantified LV global longitudinal strain (LVGLS) and LA reservoir strain (LArS) as well. Athletes also underwent cardiopulmonary exercise testing to measure peak oxygen uptake (VO2/kg). Athletes had significantly higher LVEDV and LAV compared to controls (athlete vs. control; LVEDV: 161±25 vs. 118±21 mL, LAV: 56±12 vs. 42±9 mL, both p<0.0001). LVEF was similar in the two groups (57±4 vs. 59±3%, p=NS). LAEF, passive EF and active EF were also comparable between the groups (LAEF: 56±9 vs. 55±8%, passive EF: 44±8 vs. 42±9%, active EF: 22±11 vs. 22±10%, all p=NS). LVGLS did not differ between athletes and controls either (-20±2 vs. -20±3%, p=NS), however, athletes demonstrated significantly higher LA reservoir strain (LArS: 32±8 vs. 27±6%, p<0.05). In athletes, lower resting LV myocardial mechanics was associated with a better peak exercise capacity (LVGLS vs. VO2/kg: r=0.37, p<0.05). Volumetric and mechanical characterization of the left heart using 3D echocardiography may provide a better understanding of exercise-related morphological and functional changes. In adolescent athletes, LV and LA function quantified by ejection fraction is similar to non-trained controls, despite marked dilation of both cardiac chambers. However, LA reservoir function is supernormal. Moreover, resting myocardial mechanics may show correlation with peak exercise capacity.