An implantable cardioverter/defibrillator (ICD) delivers atrial pacing under several scenarios during a tachyarrhythmia episode that is detected using a ventricular rate. In various embodiments, the atrial pacing terminates the detected tachyarrhythmia and/or enhances the classification of the detected tachyarrhythmia, thus avoiding ineffective and/or unnecessary delivery of a ventricular anti-tachyarrhythmia therapy when the detected tachyarrhythmia has a supraventricular origin.
