Pulmonary vascular distensibility was determined using pulmonary arterial pressure, pulmonary arterial wedge pressure (PAWP), and Fick cardiac output measurements at rest and during exercise, as previously described,13 in control (n=30), HFpEF (n=48), HFrEF (n=55), and PAH (n=18) patients. Mean ± SD is depicted in the graph. HFpEF (*) and HFrEF (†) patients exhibit a reduced pulmonary vascular distensibility compared to control patients (P<0.001 for both comparisons). PAH patients have a reduced distensibility compared to all three other groups (‡ P<0.001 for all three comparisons).