Echocardiographic assessment of myocardial efficiency predicts exercise performance

Cardiac function is a major determinant of cardiopulmonary fitness. This study aimed to determine if novel echocardiographic myocardial function and efficiency parameters at rest can predict exercise performance during different types of prolonged high-intensity endurance exercise. Echocardiography was performed before exercise in 40 healthy (75% males) 50.3 +/- 9.1-year-old recreational athletes. Echocardiographic parameters at rest were compared with exercise performance assessed by power output during two different exercises: A lactate threshold and cardiopulmonary exercise test (La-CPET) and a 91-km mountain bike sport cycling race. The La-CPET had a median duration of 43 (40, 45) minutes and a mean power output of 2.9 +/- 0.5 W/kg. The race had a median duration of 236 (214, 268) minutes and a mean power output of 2.1 +/- 0.5 W/kg. There was moderate left ventricular (LV) dilatation in individuals with the highest performance. The myocardial efficiency parameter, global wasted work (GWW), was positively correlated with race duration (rho = 0.42, p = 0.008) and negatively correlated with mean power output during both the La-CPET (rho = -0.43, p = 0.007) and the race (rho = -0.44, p = 0.005). In multivariable models, including LV volumes, left GWW remained an independent predictor of race duration (beta = 0.40, p = 0.007) and of mean power output during the La-CPET (beta = -0.40, p = 0.006) and the race (beta = -0.43, p = 0.003). The novel echocardiographic myocardial efficiency parameter, GWW, measured at rest, is an independent predictor of prolonged high-intensity endurance exercise performance in healthy middle-aged athletes. These findings suggest that resting myocardial efficiency parameters may aid the identification of exercise-induced LV dilatation. The graph illustrates the associations between left ventricular end diastolic volume (LVEDVi), global wasted work (GWW), and race performance (speed km/h). The variables LVEDVi and GWW go in opposite directions illustrating that a lower value of GWW and higher value of LVEDVi are associated with increased exercise performance. A low value of GWW at rest is an independent predictor of high exercise performance and may aid the identification of exercise-induced cardiac dilatation. image