There were no significant differences in mitral inflow velocity variables (E, A, E/A ratio, DT) and proBNP between patients with lower V̇o2max (< 18 mL/kg/min, n = 8) and higher V̇o2max (> 18 mL/kg/min, n = 21). However, E’ was significantly lower and E/E’ ratio was significantly higher in patients with lower V̇o2max (Table 2
). There was no significantly correlation between age, gender, LV end-diastolic and end-systolic dimensions, EF, LA volume index, and V̇o2max. None of the conventional Doppler indexes (E, A, E/A ratio, DT) correlated with V̇o2max (E, r = − 0.16, p = 0.4; A, r = − 0.11, p = 0.58; E/A ratio, r = − 0.06, p = 0.76; DT, r = 0.15, p = 0.44). However, E’ was significantly correlated with V̇o2max (r = 0.41, p = 0.024) [Fig 1]
. E/E’ ratio was inversely correlated with V̇o2max (r = − 0.47, p = 0.0106) [Fig 2]
. proBNP and log-transformed proBNP did not correlate with V̇o2max (r = − 0.2, p = 0.33; and r = − 0.08, p = 0.68, respectively). Of all the echocardiographic and clinical parameters assessed, E/E’ ratio had the best correlation with exercise capacity (r = − 0.47) and was the strongest independent predictor of V̇o2max by multivariate analysis (p = 0.0106).