1. A method of determining alternans data of an ECG signal, the method comprising: determining at least one value representing at least one morphology feature of each beat of the ECG signal; generating a set of data points based on a total quantity of values and a total quantity of beats, the data points each including a first value determined using a first mathematical function and a second value determined using a second mathematical function; separating the data points into a first group of points and a second group of points; and generating a feature map by plotting the first group of points and the second group of points in order to assess an alternans pattern of variation.