Methods and systems for treating ventricular arrhythmias

A method, of treating a fast ventricular arrhythmia, comprising:

• determining a value of a parameter indicative of at least one of vagal activity and peripheral sympathetic activity in a patient experiencing a fast ventricular arrhythmia;
• if the value is in a range indicating the ventricular arrhythmia is more likely to reflect predominant sympathetic activity than predominant vagal activity, delivering painless therapy to the patient;
• and
• if the value is outside the range, delivering a second therapy, comprising at least one of defibrillation and electrical cardioversion, to the patient,
• wherein the parameter comprises an indicator of a rate of an intrinsic atrial pacemaker in the patient's heart.

An implantable cardiac device, for treating a fast ventricular arrhythmia, comprising:

• a determining module that determines a value of a parameter indicative of a rate of an intrinsic atrial pacemaker of a heart of a patient experiencing a fast ventricular arrhythmia (FVA);
• and
• a delivery module, programmed to deliver a first therapy for terminating the FVA to the patient if the value indicates the rate is equal to or higher than a threshold, and to deliver a second therapy for terminating the FVA, different from the first therapy, to the patient if the value indicates the rate is lower than the threshold,
• wherein the first therapy comprises anti-tachycardia pacing, and the second therapy comprises at least one of defibrillation and electrical cardioversion.