on the multi dimensional ecg signals of step 106 principal component analysis is known to those skilled in the art and therefore will not be described in detail according to alternate embodiments the transform of step 110 may be performed by other processes such as independent component analysis ica nonlinear component analysis nlca factor analysis fa projection pursuit pp singular value decomposition svd and similar techniques at step 112 the output of the transform performed at step 110 is analyzed it should be appreciated that many different types of analyses can benefit from the method 100 as the data on which the analysis is based is most reflective of the patient 39 s actual electrical cardiac activity in a non limiting manner the following will describe several exemplary analyses that may be performed at step 112 according to an embodiment wherein the t wave segment of the pqrst complex is extracted at step 108 the analysis of step 112 may include evaluating the shape of the t wave defined by a principal pca vector the t wave shape evaluation may look for features such as flatness asymmetry and the presence of a notch which are linked to unstable cardiac electrical activity according to an embodiment wherein the t wave segment of the pqrst complex is extracted at step 108 the analysis of step 1 12 may include evaluating the shape of the t wave defined by a second pca vector the t wave shape.