## 4 Experiments and Results
### ICA as Fragmentation-Wave Enhancement Tool
Figure 10: _Cont._  
In the following subset of experiments inside the ICA series, we applied the processing over heart regions, as ECG leads can be consolidated in three main groups, related to the heart region they collect the electrical projection from. These are the antero-septal (which includes V1, V2, V3 and V4), the lateral (which includes I, aVL, V5 and V6) and the inferior (which includes II, III and aVF). The first experiment of this new set was designed to determine if the presence of _fragmentation_ in the ECG would make a difference in ICA output when sorted by kurtosis. To do so, we proceeded as follows, using the control ECGs and for their synthetically fragmented replications. First, the beat templates were created according to the method described before. ICA was secondly applied over them and the outputs were sorted according to their kurtosis. Then, the PCC was computed among control and  
Figure 11: Effect of the different parameters of the subrogated fragmented wave over the \(\rho_{RMSE}\) coefficient using the ICA twelve-lead model. Values lower than 0 correspond with RMSE higher in the ECG than in the principal components, values higher than 0 correspond with RMSE higher in principal components than in the ECG. (**a**) Effect of the fragmented wave amplitude; (**b**) Effect of the fragmented wave width; (**c**) Effect of the cycle number of fragmented waves; (**d**) Effect of the number of affected leads. Figure 10: Different measurements for ICA applied over twelve-lead ECG. (**a**) Distribution of \(\rho_{RMSE}\) coefficient for each independent component, \(\rho_{RMSE}\) values lower than zero represents values of RMSE over ECG greater than values of RMSE over ICA output. (**b**) Ratio of fragmentation wave enhancement for each independent component, ratio of cases where the \(\rho_{RMSE}\) coefficient is greater than zeros. (**c**) Cumulative ratio of fragmentation wave enhancement, this ratio is computed by joining the results of isolated independent components. fragmented replications. PCC was stablished as the driver to identify the portion of the signal transferred during the process. This technique was applied for each region. Results were merged into confusion matrices, hereafter presented in Table 6. As it can be observed, the use of regionalized models plus kurtosis sorting improved the matching between independent components compared with the twelve-lead model, moreover the, \(\epsilon_{disp}\), dispersion coefficients were 0.23, 0.21, and 0.26, which are lower than the twelve-lead model. The next experiment numerically quantified the _improvement on the fragmentation wave information using \(\rho_{RMSE}\) coefficient_. In this experiment we used the complete subrogated model including 400 control cases and 400 synthetically fragmented replications. The process followed in this case was the following. First, for pair-control-fragmented cases, ICA was computed over each region separately. Then, the outputs were sorted according to their kurtosis. Afterward, we computed the PCC between the kurtosis sorted output of fragmented case and control case. Finally, outputs of control cases were sorted according to PCC and the \(\rho_{RMSE}\) coefficient was computed. The \(\rho_{RMSE}\) coefficient distribution is shown in Figures 12a, 13a and 14a. As it can be observed, the distribution is almost flat due to the sparse information of the fragmented waves dealt in each component. This effect is clearly visible in Figures 12b, 13b and 14b, which show the ratio of cases that exhibited a certain enhancement, understood as the cases where \(\rho_{RMSE}\) coefficient is greater than zero. We can observe the similarity between the enhancement ratio of each independent component in the three panels. The values are close to 0.75 of enhancement. Finally, we computed the cumulative ratio of enhancement in order to select several components that combined would eventually contains improvement in the mentioned ratio of the cases.