Reference ranges for functional and structural echocardiographic parameters in asian athletes: a systematic review and meta-analysis
Authors: Hon J , Paik B , Ng JJ , Choong AMTL , Yeo TJ 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background/Introduction
Physiologic cardiac remodelling is common in elite athletes, including changes such as increased left ventricle size and left ventricular wall thickness. These changes often overlap with those from pathological cardiac conditions - for instance dilated cardiomyopathy and hypertrophic cardiomyopathy - leading to diagnostic uncertainty. The availability of reference ranges specific to elite athletes, particularly Caucasian and Black ethnicities, facilitates accurate differentiation between physiology and pathology. However, there remains a paucity of Asian data despite an increased representation in global sport.

Purpose
To perform a systematic review and meta-analysis of cardiac imaging studies in Asian elite athletes and obtain reference values for commonly utilised parameters in this population.

Methods
We searched MEDLINE via PubMed, Embase, and the Cochrane Database for relevant studies from inception till 27th July 2021. We included observational studies that reported relevant cardiac imaging parameters in Asian elite athletes. We excluded studies that did not report gender-specific cardiac imaging parameters. After study selection and data extraction, we performed random effects meta-analysis of means to obtain the weighted mean of each relevant cardiac imaging parameter stratified by gender.

Results
We included a total of eight studies with relevant echocardiographic data from East Asia, South Asia and West Asia which comprised a total of 799 male and 206 female elite athletes participating in endurance and mixed sport disciplines. We excluded data pertaining to athletes participating in skill and power disciplines in a post-hoc manner due to paucity of data and extreme data ranges. The weighted mean left ventricular mass (g) was 211.5 (95% CI 202.6 - 220.3, I2 = 85.8%) for males, and 139.3 (95% CI 132 - 146.7, I2 = 88.2%) for females. The weighted mean left ventricular mass indexed to body surface area (g/m2) was 103.1 (95% CI 99.2 - 106.9, I2 = 79.4%) for males, and 75.1 (95% CI 71.5 - 78.6, I2 = 86.1%) for females. For left ventricular end diastolic diameter (mm), the weighted mean was 54.4 (95% CI 53.1 - 55.7, I2 = 97.3%) for males, and 47.2 (95% CI 46.2 - 48.3, I2 = 89.3%) for females. Lastly, the weighted mean left ventricular wall thickness (mm) was 9.9 (95% CI 9.6 - 10.2, I2 = 91.3%) for males, and 8.7 (95% CI 8.5 - 9, I2 = 80.7%) for females.

Conclusions
This is the first meta-analysis that provides preliminary echocardiographic reference ranges for Asian elite athletes. Statistical heterogeneity, however, is high in most outcome measures. This is likely due to the presence of confounders such as study demographics. Due to a paucity of studies, further subgroup or stratified analyses could not be performed meaningfully. More large-scale observational studies are required such that more sport, gender or region-specific data could be generated.