1. A method of detecting arrhythmic electrocardiogram (ECG) signals, the method comprising: defining a plurality of threshold heart rates and rate-dependent sensitivity levels for detecting arrhythmic ECG episodes, wherein more clinically relevant heart rates are assigned rate-dependent sensitivity levels with higher sensitivities; monitoring ECG signals associated with a patient using a monitoring device; and processing the monitored ECG signals using the plurality of threshold heart rates and rate-dependent sensitivity levels to detect and capture arrhythmic ECG segments.