A method of analyzing electrocardiograph (ECG) data includes receiving a first representative ECG of a patient and isolating a first principal component, a second principal component, and a third principal component of the first representative ECG. The principal components are isolated by selecting a portion of the first representative ECG relating to depolarization, calculating a covariance matrix based on the portion of the first representative ECG, conducting a principal component analysis of the covariance matrix, and selecting a first component of the principal component analysis as the first principal component, the second component of the principal component analysis as the second principal component, and the third component of the principal component analysis as the third principal component. A depolarization subspace is then formed based on the first principal component, second principal component, and the third principal component of the first representative ECG.