What we do know from the results from hemodynamic monitoring trials is that direct measurement of filling pressures correlates strongly with risk of HF events, and that in patients in whom we are able to effectively reduce filling pressures, we are often able to prevent hospitalization.  Data from the COMPASS-HF (Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure Study) trial of an implantable pulmonary artery diastolic pressure monitoring device suggested that the risk of the HF hospitalization correlates very closely with measured pulmonary artery diastolic pressure.  In that study patients had a linear increase for the risk for HF hospitalization once the pulmonary artery diastolic pressure exceeded 18 mmHg.^[13]

In other words, overall the data from COMPASS-HF suggest very strongly that perhaps the signal that we have been missing in longitudinal HF management is the ability to directly monitor filling pressures, and pulmonary artery diastolic pressure in particular.