Fig. 3

By measuring the interval from the start of the P wave in the electrocardiogram to the start of the A´ wave in the TDI spectrum, the electromechanical coupling time can be obtained (A). The three arrows from right to left respectively represent the positions of the lateral wall of the mitral annulus, the interatrial septal annulus, and the lateral wall of the tricuspid annulus in the Four-chamber view (B).