Assessment of the athlete's heart is challenging because of a phenotypic overlap between reactive physiological adaptation and pathological remodelling. The potential value of myocardial deformation remains controversial in identifying early cardiomyopathy.

To identify the echocardiographic phenotype of athletes using advanced two-dimensional speckle tracking imaging, and to define predictive factors of subtle left ventricular systolic dysfunction.

In total, 191 healthy male athletes who underwent a preparticipation medical evaluation at Nancy University Hospital between 2013 and 2020 were included. Clinical and echocardiographic data were compared with 161 healthy male subjects from the STANISLAS cohort. Borderline global longitudinal strain value was defined as<17.5%.

Athletes demonstrated lower left ventricular ejection fraction (57.9±5.3% vs. 62.6±6.4%; P<0.01) and lower global longitudinal strain (17.5±2.2% vs. 21.1±2.1%; P<0.01). No significant differences were found between athletes with and without a borderline global longitudinal strain value regarding clinical characteristics, structural echocardiographic features and exercise capacity. A borderline global longitudinal strain value was associated with a lower endocardial global longitudinal strain (18.8±1.2% vs. 22.7±1.9%; P=0.02), a lower epicardial global longitudinal strain (14.0±1.1% vs. 16.6±1.2%; P<0.01) and a higher endocardial/epicardial global longitudinal strain ratio (1.36±0.07 vs. 1.32±0.06; P<0.01). No significant difference was found regarding mechanical dispersion (P=0.46).

Borderline global longitudinal strain value in athletes does not appear to be related to structural remodelling, mechanical dispersion or exercise capacity. The athlete's heart is characterized by a specific myocardial deformation pattern with a more pronounced epicardial layer strain impairment.