Speckle tracking evaluation in endurance athletes: the "optimal" myocardial work

To analyze left ventricular myocardial deformation and contractile reserve in endurance athletes at rest and during exercise, and their possible correlations with functional capacity. The athlete's heart in endurance training is characterized by physiologic eccentric remodeling, with left ventricle adaptation at rest and echocardiographic parameters at low end of normality. Assessment of left ventricle systolic function and contractile reserve has an important role in the decision-making and in differential diagnosis with cardiomyopathies. Standard echo, lung ultrasound, left ventricle 2D speckle-tracking strain and myocardial work were performed at rest and during exercise in endurance athletes and in age- and sex-comparable healthy controls. 350 endurance athletes (male sex 58.5%; 31.6 ± 4.2 years) and 150 healthy controls were enrolled. Left ventricular ejection fraction at baseline was comparable between the two groups. Resting left ventricular global longitudinal strain was reduced in endurance athletes (- 18.4 ± 2.6% vs. - 22.4 ± 3.3% in controls; p < 0.01). Myocardial work efficiency did not show significative difference between the two groups. At peak exertion during exercise stress echocardiography, endurance athletes showed better exercise capacity and peak VO₂ consumption (58.6 ± 10.2 ml/kg/min vs 38.6 ± 3.3 ml/kg/min in controls, p < 0.0001), associated with a preserved contractile reserve and augmented pulmonary artery systolic pressure. By multivariable analysis myocardial work efficiency at rest was closely related to maximal watts (p < 0.0001), peak VO₂, (p < 0.0001), left ventricular E/e' (p < 0.001) and number of B-lines (p < 0.001), all measured at peak effort. Myocardial work efficiency shows less load-dependency than global longitudinal strain. Normal resting values of myocardial work efficiency in endurance athletes suggest a physiological remodeling, associated with a better exercise capacity and preserved contractile reserve during physical effort.