Described herein are devices, systems and method that monitor heart rate and/or for arrhythmic episodes based on sensed intervals that can include true R-R intervals as well as over-sensed R-R intervals. True R-R intervals are initially identified by comparing individual sensed intervals to a sum of an immediately preceding two intervals, and/or an immediately following two intervals, as well as by comparing sensed intervals to a mean or median of durations of intervals already identified as true R-R intervals. Individual intervals in a remaining ordered list of sensed intervals (from which true R-R intervals were removed) are classified as either a short or long interval, and over-sensed R-R intervals are identified based on the results thereof. Embodiments can be used to reduce reporting of and/or inappropriate responses to false positive tachycardia detections.
