An implantable medical device connectable to electrodes (119, 121, 126, 127, 128, 129, 132, 134) configured to be located proximate to one or more atrial or ventricular sites, the electrodes (119, 121, 126, 127, 128, 129, 132, 134) configured to sense cardiac events over a period of time that includes a detection period followed by an observation period, wherein the implantable medical device comprises: a memory configured to store program instructions; and one or more processors configured, when executing the program instructions, to: detect a ventricular arrhythmia episode and select a corresponding ventricular tachycardia/ventricular fibrillation (VT/VF) therapy based on the cardiac events during at least the detection period; delay delivery of the VT/VF therapy for a self-termination period within the observation period, the self-termination period representing a time period during which the ventricular arrhythmia episode may self-terminate; analyze a stability characteristic of interest from the cardiac events sensed over at least a portion the observation period; determine an end point for the self-termination period, within the observation period; and deliver the VT/VF therapy when the ventricular arrhythmia episode continues past the end point, characterized in that the one or more processors are configured to: determine whether the stability COI is stable or unstable and increasing or decreasing; and determine a first end point for the self-termination period when the stability COI exhibits an unstable and decreasing rate in combination with an unstable amplitude. a memory configured to store program instructions; and one or more processors configured, when executing the program instructions, to: detect a ventricular arrhythmia episode and select a corresponding ventricular tachycardia/ventricular fibrillation (VT/VF) therapy based on the cardiac events during at least the detection period; delay delivery of the VT/VF therapy for a self-termination period within the observation period, the self-termination period representing a time period during which the ventricular arrhythmia episode may self-terminate; analyze a stability characteristic of interest from the cardiac events sensed over at least a portion the observation period; determine an end point for the self-termination period, within the observation period; and deliver the VT/VF therapy when the ventricular arrhythmia episode continues past the end point, characterized in that the one or more processors are configured to: determine whether the stability COI is stable or unstable and increasing or decreasing; and determine a first end point for the self-termination period when the stability COI exhibits an unstable and decreasing rate in combination with an unstable amplitude. detect a ventricular arrhythmia episode and select a corresponding ventricular tachycardia/ventricular fibrillation (VT/VF) therapy based on the cardiac events during at least the detection period; delay delivery of the VT/VF therapy for a self-termination period within the observation period, the self-termination period representing a time period during which the ventricular arrhythmia episode may self-terminate; analyze a stability characteristic of interest from the cardiac events sensed over at least a portion the observation period; determine an end point for the self-termination period, within the observation period; and deliver the VT/VF therapy when the ventricular arrhythmia episode continues past the end point, characterized in that the one or more processors are configured to: determine whether the stability COI is stable or unstable and increasing or decreasing; and determine a first end point for the self-termination period when the stability COI exhibits an unstable and decreasing rate in combination with an unstable amplitude. determine whether the stability COI is stable or unstable and increasing or decreasing; and determine a first end point for the self-termination period when the stability COI exhibits an unstable and decreasing rate in combination with an unstable amplitude.