Embodiments of the present disclosure describe methods of adaptive arrhythmia detection comprising monitoring ECG signals of a patient via a patient medical device, detecting and capturing ECG segments based on a heart rate threshold and an initial sensitivity level associated with the heart rate threshold； and adjusting the sensitivity level based on previously captured ECG segments. Embodiments of the present disclosure further describe patient medical devices comprising one or more electrodes and sensing circuitry for monitoring ECG signals of a patient； and a processing module configured to receive the monitored ECG signal, wherein the processing module detects and captures ECG segments based on a plurality of heart rate thresholds and one or more sensitivity levels associated with each of the heart rate thresholds, and adjusts at least one of the one or more sensitivity levels associated with each of the heart rate thresholds.
