The present invention is for a method and apparatus for extracting optimum ECG data from within a optimum timeperiod. The method and apparatus require setting a timeperiod in which to extract ECG data, setting thresholds for noise, determining a segment with stable heart rate, and to measure the ECG data of the time period. Once the parameters are set and the data is collected, optimum data according to the parameters set by the user are extracted for use and analysis, such that the ECGs that are free from noise and have a stable heart rate are retrieved from the desired timeperiod window. The invention can be used in a software program, may be programmable into a Holter monitors, or as well as applicability in other related monitoring devices.