1. A method of cardiac signal analysis in an implantable medical device (IMD), the IMD including a number of implantable electrodes and operational circuitry for analyzing signals obtained via the implantable electrodes, the IMD further comprising a therapy delivery capacitor and a charging circuit associated with the therapy delivery capacitor, the charging circuit configured to selectively charge the therapy delivery capacitor to prepare for delivery of cardiac cardioversion or defibrillation therapy when enabled by the operational circuitry, the method comprising: the operational circuitry detecting a set of events in a signal including detecting a plurality of cardiac cycles; the operational circuitry analyzing the set of events to determine whether any of the set of events meets criteria for likely overdetection and applying flags to each event of a subset of the events which meet criteria for likely overdetection; the operational circuitry generating a corrected interval for each event in the subset of events, wherein the corrected interval includes an interval preceding an event from the subset of events combined with an interval following the event; the operational circuitry determining that a cardiac arrhythmia is likely occurring using at least one corrected interval; and the operational circuitry, in response to determining that the cardiac arrhythmia is likely occurring, performing a charge confirmation analysis comprising analyzing a pattern of flags within the set of events to determine whether therapy should be delivered.