Peak exercise oxygen uptake and left ventricular systolic and diastolic function and arterial mechanics in healthy young men

Echocardiography can be used to estimate myocardial contractility by the assessment of the circumferential end-systolic stress-corrected left ventricular (LV) fractional shortening measured at midwall level (stress-corrected MWS). Whether stress-corrected MWS at rest predicts exercise peak oxygen uptake (peak VO2) is unknown. Also, it is not known whether the propagation rate of the early LV filling wave (E wave propagation rate, V-p), a new pre-load insensitive index of LV diastolic function, and echocardiographically assessed indices of arterial stiffness correlate to peak VO2. Accordingly, we performed echocardiographic studies and exercise tests with respiratory gas analysis in 15 young healthy male subjects (mean age 27 years, range 18-36). Neither stress-corrected-MWS (r=0.20, P = NS) nor ejection fraction (r = 0.05, P = NS) correlated significantly with peak VO2. Adjustment for age and resting heart rate had no effect on the results. In separate multiple regression models adjusting for standard covariates (age, LV size and heart rate), peak VO2 correlated with V-p (beta = 0.98, P<0.01), as well as with E/A (beta = 0.85, P<0.01), and with the isovolumic relaxation time (indicator of LV relaxation) (beta = -0.59, P<0.05). Arterial stiffness indices showed no significant relation to peak VO2. We conclude that in young healthy male subjects, resting myocardial contractility and arterial stiffness are not significant correlates of peak VO2, whereas LV diastolic function, and in particular V-p, influences the variability of peak VO2.