An apparatus comprising: a first implantable sensor configured to produce a first electrical sensor signal representative of cardiac depolarization events of a heart of a subject; a second implantable sensor configured to produce a second electrical sensor signal representative of hemodynamic function of the heart; a signal analyzer circuit, communicatively coupled to the first and second implantable sensors (505, 510), configured to: detect an arrhythmic event from the first sensor signal; and calculate hemodynamic stability in response to the arrhythmic event detection using the second sensor signal; and an arrhythmia discrimination circuit, communicatively coupled to the signal analyzer circuit and the first implantable sensor, configured to: preselect a plurality of candidate arrhythmia discrimination algorithms from among a set of algorithms implementable by the arrhythmia discrimination circuit; classify the detected arrhythmia using each of the candidate arrhythmia discrimination algorithms; weight the arrhythmia classifications by the candidate algorithms according to a calculated hemodynamic stability produced by the signal analyzer circuit; select, according to the weighting, an arrhythmia discrimination algorithm from among the plurality of candidate arrhythmia discrimination algorithms; classify the detected arrhythmia using the selected arrhythmia discrimination algorithm; and provide the arrhythmia classification to a user or process. a first implantable sensor configured to produce a first electrical sensor signal representative of cardiac depolarization events of a heart of a subject; a second implantable sensor configured to produce a second electrical sensor signal representative of hemodynamic function of the heart; a signal analyzer circuit, communicatively coupled to the first and second implantable sensors (505, 510), configured to: detect an arrhythmic event from the first sensor signal; and calculate hemodynamic stability in response to the arrhythmic event detection using the second sensor signal; and detect an arrhythmic event from the first sensor signal; and calculate hemodynamic stability in response to the arrhythmic event detection using the second sensor signal; and an arrhythmia discrimination circuit, communicatively coupled to the signal analyzer circuit and the first implantable sensor, configured to: preselect a plurality of candidate arrhythmia discrimination algorithms from among a set of algorithms implementable by the arrhythmia discrimination circuit; classify the detected arrhythmia using each of the candidate arrhythmia discrimination algorithms; preselect a plurality of candidate arrhythmia discrimination algorithms from among a set of algorithms implementable by the arrhythmia discrimination circuit; weight the arrhythmia classifications by the candidate algorithms according to a calculated hemodynamic stability produced by the signal analyzer circuit; select, according to the weighting, an arrhythmia discrimination algorithm from among the plurality of candidate arrhythmia discrimination algorithms; classify the detected arrhythmia using the selected arrhythmia discrimination algorithm; and provide the arrhythmia classification to a user or process.