The purpose of the PRECEDE-HF study is to collect data to compare patients whose heart failure is managed using Cardiac Compass with OptiVol (which is a tool in the device that records information about the heart that doctors can use to help treat their heart disease) combined with standard treatment methods (Access Group) to patients whose heart failure is managed by standard treatment methods only (Control Group). This comparison will show if the additional monitoring provided by Cardiac Compass with OptiVol delays the time patients are first admitted to hospital for heart failure or delays the time to death.