Electrocardiogram analyzer

An electrocardiogram analyzer comprising:

• a processor configured to receive a body surface electrocardiogram of a subject, receive an intracardiac electrocardiogram of a ventricle of a heart of the subject, perform a frequency analysis on the intracardiac electrocardiogram, set a reference point as an R wave peak in the body surface electrocardiogram based on a unit waveform of the body surface electrocardiogram, set an analysis time range of the frequency analysis in the intracardiac electrocardiogram based on a starting timing of ventricular contraction before the R wave peak and a timing of next operation of an atrium after the R wave peak and, in the analysis time range, perform the frequency analysis on the intracardiac electrocardiogram, and calculate an index value indicating a ratio of local abnormal ventricular activities in the intracardiac electrocardiogram.