A concise guide of contemporary cardiovascular imaging practices to differentiate athlete's heart in the gray zone

Athlete's heart comprises various structural and functional adaptations, imposed by systematic training and intended to serve the increased needs of the body during exercise. In most cases, athletic cardiac remodeling presents mild characteristics that are easily distinguishable from pathologic entities. However, common inherited cardiomyopathies such as hypertrophic, dilated, or arrhythmogenic may also affect athletes or athletic individuals, while athlete's heart in a more pronounced form (frequently called "gray" zone) should be distinguished from early stages of the above-mentioned cardiomyopathies. Based on these assumptions, cardiovascular imaging remains the key process that should be applied to accurately differentiate between normal and abnormal phenotypes, facilitating thus pre-participation screening along with early detection and handling of underlying cardiomyopathies. Recent advances in both echocardiography and cardiovascular magnetic resonance offer new diagnostic potentials, making, however, "method" and "time" selection rather complicated. The aim of this review is to provide a short and comprehensive guide for differentiating athlete's heart in the gray zone from cardiomyopathies, encompassing all contemporary tools of imaging modalities into easily applicable and hierarchically appropriate algorithms.