Mean left atrial pressure (mLAP) as a function of exercise intensity and the considered optimal AVD. The black line represents the mLAP values when the optimal AVD identified at baseline is maintained across all exercise stages. The gradient black-to-red line illustrates the mLAP values when the AVD is optimized for each individual exercise stage. The definition of the exercise intensity zones can be found in the caption of Figure 6. AVD, atrio-ventricular delay; LV, left ventricle.