Left ventricular speckle tracking-derived cardiac strain and cardiac twist mechanics in athletes: a systematic review and meta-analysis of controlled studies

Background The athlete’s heart is associated with physiological remodelling as a consequence of repetitive cardiac loading. Exercise training effect on left ventricular (LV) cardiac strain and twist mechanics are equivocal and no meta-analysis has been conducted to date. Objective The objective of this systematic review and meta-analysis is, (1) to review the literature pertaining to different forms of athletic training on cardiac strain and twist mechanics; (2) to determine the influence of traditional and contemporary sporting classifications on cardiac strain and twist mechanics. Design Systematic review and meta-analysis. Data Sources PubMed/MEDLINE, Web of Science and ScienceDirect. Inclusion criteria Controlled studies of aged matched male participants aged 18-45years that used 2-D speckle tracking with a defined athlete sporting discipline and a control group not engaged in training programmes. Data Extraction and Analysis Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regressions. Results Thirteen studies of 955 participants; (controls n=355; athletes n=600) were included. Meta-analyses showed no athlete-control differences in LV strain or twist mechanics. However, moderator analyses showed greater LV twist in high static, low dynamic athletes (d= -0.76, 95% CI -1.32 to -0.20, p<0.01) compared with controls. Peak untwisting velocity (PUV) was greater in high static, low dynamic athletes (d= -0.43, 95% CI -0.84 to -0.03, p<0.05) but less than controls in high dynamic, high static athletes (d= 0.79, 95% CI 0.002 to 1.58, p=0.05). Elite endurance athletes had significantly less twist and apical rotation than controls (d= 0.63, 95% CI 0.17 to 1.09, p<0.01; d= 0.64, 95% CI 0.27 to 1.00, p=0.001, respectively) yet no differences in basal rotation compared with controls. Meta-regressions showed LV mass index was positively associated with global longitudinal (b= 0.01, 95% CI 0.002 to 0.02, p<0.05) and apical circumferential strain (b= 0.01, 95% CI -0.001 to 0.01, p=0.05), while systolic blood pressure was negatively associated with PUV (b= -0.06, 95% CI -0.13 to -0.001, p=0.05). Conclusion Echocardiographic 2-D speckle tracking can identify subtle physiological adaptations to cardiac strain and twist mechanics between athletes and healthy controls. Differences in STE derived parameters can be identified using suitable sporting categorisations.