In implantable medical devices such a pacemaker or cardioverter/defibrillators (ICDs) and systems including such a device and an external programmer a measure of a hemodynamic parameter such as the cardiac output, the stroke volume, or the contractility of a patient is used to trend heart failure or in an AV/VV optimization scheme. The implantable medical device is adapted to measure the cardiac impedance and the cardiac impedance data is used to determine impedance morphology curves, which, in turn, are used to compute a measure of the hemodynamic parameter.
