Poor Cardiac Output Reserve in Pulmonary Arterial Hypertension is Associated With Right Ventricular Stiffness and Impaired Interventricular Dependence.

Patients with poor exercise CI reserve exhibit poor exercise RV afterload, stiffness, and right-sided filling pressures that depress LV filling and stroke work. High afterload and RV stiffness were the best correlates to low flow reserve in PAH. Exercise unmasked significant pathophysiologic PAH differences unapparent at rest.