Systolic efficiency slope (SES) - the S’/ VO2relationship
We took advantage of the linear augmentation pattern of systolic velocity and its close relationship with VO2 to derive individual regression lines for VO2 and S’. This new parameter represents the amount of S’ associated with a 1 unit increase in VO2 and therefore a measure of myocardial efficiency. A relationship between the SES slope was observed for VO2peak and septal S’; r = 0.57; p<0.001 and lateral S’; r = 0.53; p<0.001) (Figure 3). We also confirmed the validity of these findings by creating models for OUES, a submaximal measures shown to predict total cardiopulmonary capacity10,11. A significant relationship was found between SES slope and the OUES (septal r = 0.54; p<0.001, lateral r = 0.52; p=0.001).
Inter- and intraobserver reproducibility
There was excellent inter- and intra-observer reproducibility for all measurements by CPET (VO2peak and OUES). For echocardiography parameters there was good to excellent inter- and intraobserver reproducibility for S’ and E’ at rest and exercise. There was lower inter- and intraobserver reproducibility seen for LVEF and GLS both at rest and exercise (Appendix 1).