Data from trials of implantable hemodynamic monitors for HF have revealed a lot about the evolution of HF decompensation.  Figure 10, drawn from data from the COMPASS-HF (Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure Study) trial,^[6] underscores that whether patients had a low ejection fraction (in blue) or a preserved ejection fraction (in red), filling pressures rose very gradually, often over 2–3 weeks in anticipation of the HF event.

So while to many patients and clinicians HF decompensation sometimes appears to be an abrupt phenomenon, these data suggest that it develops gradually over the course of time, independent of ejection fraction.  This window of gradual rise in filling pressures (shown in blue in the Figure), which often precedes the development of typical symptoms of HF, represents a key opportunity to intervene to prevent HF decompensation well before it happens.