Methods, devices and program products are provided. The method is under control of one or more processors within an implantable medical device (IMD), obtains cardiac signals that comprise candidate episodes over a period of time and updates an episode count and episode density clock based on the candidate episodes within the period of time. Further, the method determines whether the candidate episodes are indicative of a ventricular storm arrhythmia based on the episode count and episode density clock, identifies a storm origin characteristic of interest preceding onset of the candidate episodes and directs the IMD to perform a storm intervention based on the identifying operation.
