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Chapter 6 Additional clinical applications 189

























                     Figure 6.4. Quantitative analysis of predictive performance. (A) Mean  QRSd per
                     stimulation protocol; (B) Measured vs. predicted  QRSd.

                     and  QRSd, respectively. In detail, we observed that the model
                     performed better in predicting the outcome under LV and BiV pac-
                     ing than in RV pacing (correlation coefficients of 0.9, 0.52, and
                     0.46, respectively). Furthermore, no significant bias in LV and RV
                     prediction was apparent, but an over-estimation of QRS shorten-
                     ing was observed under biventricular pacing. A detailed compar-
                     ison of measured and computed  QRSd for two representative
                     cases can be seen in Fig. 6.2. Wave propagation for these two cases
                     are illustrated in Fig. 6.3.(SeeFig. 6.4.)


                     6.1.4 Discussion
                        This study aimed at a real-world scenario in which only base-
                     line, standard of care data is available for computational model-
                     ing. Despite the limitations in the data, the changes in QRS com-
                     plex duration for 75% of all protocols could be predicted. The
                     model could also identify two out of four patients who did not see
                     a shortening of their QRS complex under pacing. The computa-
                     tion of the exact electrophysiology post CRT was more challeng-
                     ing. This can be explained by limitations in the data, model and
                     the lack of precise information about the CRT device. For instance,
                     the delay between device stimulation and spontaneous stimula-
                     tion had to be guessed, although it was found to significantly affect
                     the QRS complex duration under pacing. Being able to run these
                     models during the procedure, when more data is available, could
                     prove valuable by enabling interactive model adjustment to the
                     patient’s physiology, for more precise predictions.
                        In summary, the feasibility of virtual CRT using patient-specific
                     computational models was illustrated. The model could capture
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