Why might someone with aortic stenosis be prescribed phosphodiesterase inhibitors?

Post operatively: People are reluctant to give pre op patients with critical aortic stenosis inotropes. They stimulate the heart, but in the case of dobutamine and milrinone (most common phosphodiesterase inhibitor) they also drop the aortic pressure past the valve, and that can be very bad. Post op, PDE's can be preferable to other inotropes because sympathomimetics worsen the stiffness of the thick LV.