Cardiac structure and function in elite female athletes: A systematic review and meta-analysis

Abstract

We conducted a meta-analysis to synthesize the best available evidence comparing cardiac biventricular structure and function using cardiac magnetic resonance imaging (CMR) and transthoracic echocardiography (TTE) in elite female athletes and healthy controls (HC). Chronic exposure to exercise may induce cardiac chamber enlargement as a means to augment stroke volume, a condition known as the "athlete's heart." These changes have not been clearly characterized in female athletes. Multiple databases were searched from inception to June 18, 2019. Outcomes of interest included left ventricular (LV) and right ventricular (RV) dimensional, volumetric, mass, and functional assessments in female athletes. Most values were indexed to body surface area. The final search yielded 22 studies, including 1000 female athletes from endurance, strength, and mixed athletic disciplines. CMR-derived LV end-diastolic volume (LVEDV) and RV end-diastolic volume (RVEDV) were greater in endurance athletes (EA) versus HC (17.0% and 18.5%, respectively; both p < 0.001). Similarly, TTE-derived LVEDV and RVEDV were greater in EA versus HC (16.8% and 28.0%, respectively; both p < 0.001). Both LVEF and RVEF were lower in EA versus HC, with the most pronounced difference observed in RVEF via TTE (9%) (p < 0.001). LV stroke volume was greater in EA versus HC via both CMR (18.5%) and TTE (13.2%) (both p < 0.05). Few studies reported data for the mixed athlete (MA) population and even fewer studies reported data for strength athletes (SA), therefore a limited analysis was performed on MA and no analysis was performed on SA. This evidence-synthesis review demonstrates the RV may be more susceptible to ventricular enlargement. General changes in LV and RV structure and function in female EA mirrored changes observed in male counterparts. Further studies are needed to determine if potential adverse outcomes occur secondary to these changes.

Keywords: athlete's heart; cardiac magnetic resonance imaging; female athletes; right ventricular enlargement.

FIGURE 1

Forest plot showing mean differences between (EA vs. HC) in LVEDV indexed to BSA (ml/m²) using CMR (a), RVEDV indexed to BSA (ml/m²) using CMR (b), LVEDV indexed to BSA (ml/m²) using TTE (c), and RVEDV indexed to BSA (ml/m²) using TTE (d). The size of the square corresponds to the weight of each study. The diamonds and their width represent the pooled mean difference (MD) and the 95% confidence intervals (95% CIs), respectively. BSA, body surface area; CMR, cardiac magnetic resonance imaging; LVEDV, left ventricular end‐diastolic volume; LVESV, left ventricular end‐systolic volume; RVEDV, right ventricular end‐diastolic volume; RVESV, right ventricular end‐systolic volume; TTE, transthoracic echocardiography

FIGURE 2

Bar graph showing mean values for LVEDV indexed to BSA (ml/m²), LVSV indexed to BSA (ml/m²), and LVEF (%) (a) for EA and HCs obtained with CMR. Mean values for RVEDV indexed to BSA (ml/m²), RVSV indexed to BSA (ml/m²), and RVEF (%) (b) for EA and HCs using CMR (b). Statistically significant differences are indicated with an asterisk (*). BSA, body surface area; CMR, cardiac magnetic resonance imaging; LVEDV, left ventricular end‐diastolic volume; LVEF, left ventricular ejection fraction; LVSV, left ventricular stroke volume; RVEDV, right ventricular end‐diastolic volume; RVEF, right ventricular ejection fraction; RVSV, right ventricular stroke volume

FIGURE 3

CMR images obtained from an elite female athlete and a normal healthy female. Images obtained from an elite female athlete include four chamber (a), three chamber (b), and short axis (c) views. Measurements obtained are as follows: LVEDV 102 ml/m², LVESV 39 ml/m², LVSV 63 ml/m², and LVEF 62%, RVEDV 116 ml/m², RVESV 47 ml/m², RVSV 69 ml/m², RVEF 59%. A CMR from a healthy female is used for visual comparison which include four chamber (d), three chamber (e), and short axis (f) views. Measurements obtained are as follows: LVEDV 80 ml/m², LVESV 35 ml/m², LVSV 46 ml/m², and LVEF 57%, RVEDV 67 ml/m², RVESV 26 ml/m², RVSV 41 ml/m², RVEF 59%. All values not represented with a % are indexed to BSA. This figure highlights differences in ventricular size between female athletes and healthy controls. 2 Ch =2 chamber; 3 Ch =3 chamber; 4 Ch =4 chamber. BSA, body surface area; CMR, cardiac magnetic resonance imaging; LV, left ventricle; LVEDV, left ventricular end‐diastolic volume; LVESV, left ventricular end‐systolic volume; LVEF, left ventricular ejection fraction; LVSV, left ventricular stroke volume; RV = right ventricle; RVEDV, right ventricular end‐diastolic volume; RVESV, right ventricular end‐systolic volume; RVEF, right ventricular ejection fraction; RVSV, right ventricular stroke volume