Objective: Athlete's heart is associated with left ventricular (LV) hypertrophy (LVH), and "supranormal" cardiac function, suggesting that this is a physiological process. Hypertrophy alone cannot explain increase in cardiac function, therefore, other mechanisms, such as better ventriculo-arterial coupling might be involved.
Methods: We studied 60 male (21 +/- 3 years) subjects: 27 endurance athletes, and a control group of 33 age-matched sedentary subjects. We assessed global systolic and diastolic LV function, short- and long-axis myocardial velocities, arterial structure and function and ventriculo-arterial coupling, endothelial function by flow-mediated dilatation, and amino-terminal pro-brain natriuretic peptide (NT-proBNP) and biological markers of myocardial fibrosis and of oxidative stress.
Results: Athletes had "supranormal" LV longitudinal function (12.4 +/- 1.0 vs 10.1 +/- 1.4 cm/s for longitudinal systolic velocity, and 17.4 +/- 2.6 vs 15.1 +/- 2.4 cm/s for longitudinal early diastolic velocity, both P < 0.01), whereas ejection fraction and short-axis function were similar to controls. Meanwhile, they had better endothelial function (16.7 +/- 7.0 vs 13.3 +/- 5.3%, P < 0.05) and lower arterial stiffness (pulse wave velocity 7.1 +/- 0.6 vs 8.8 +/- 1.1 m/s, P = 0.0001), related to lower oxidative stress (0.259 +/- 0.71 vs 0.428 +/- 0.88 nmol/mL, P = 0.0001), with improved ventriculo-arterial coupling (37.1 +/- 21.5 vs 15.5 +/- 13.4 mmHg.m/s(3)x 10(3), P = 0.0001). NT-proBNP and markers of myocardial fibrosis were not different from controls. LV longitudinal function was directly related to ventriculo-arterial coupling, and inversely related to arterial stiffness and to oxidative stress.
Conclusions: "Supranormal" cardiac function in athletes is due to better endothelial and arterial function, related to lower oxidative stress, with optimized ventriculo-arterial coupling; athlete's heart is purely a physiological phenomenon, associated with "supranormal" cardiac function, and there are no markers of myocardial fibrosis.