Wolsk E, et al. - Among subjects prospectively included in the REDUCE-LAP HF (Reduce Elevated Left Atrial Pressure in Patients With Heart Failure) trials and HemReX (Effect of Age on the Hemodynamic Response During Rest and Exercise in Healthy Humans) study, researchers looked for the central (eg, heart rate, stroke volume [SV], filling pressure) and peripheral factors (eg, oxygen use by skeletal muscle, body mass index [BMI]) during exercise which were most powerfully related to the presence of heart failure and preserved ejection fraction (HFpEF) vs healthy control subjects exercising at the same workload. They used right-sided heart catheterization to determine hemodynamic response at peak exercise among 108 patients with HFpEF; the results were compared with that of 42 healthy control subjects. This allowed the determination of hemodynamic differences that were not due to the workload. Pulmonary capillary wedge pressure (PCWP), BMI, and SV were the three key variables that were found to be independently associated with the presence of HFpEF patients vs healthy controls exercising at the same workload.