Quantitative comparison of two cardiac electrical imaging methods to localize pacing sites

Electrocardiographic imaging (ECGI) is a technology with great potential to support pre-procedure planning for ablation interventions. However, since the inverse problem it tries to solve is ill-posed, it requires regularization to stabilize the solutions. There have been multiple approaches to attain this objective with different regularization techniques that impose spatial or temporal behaviour on the solution based on prior electrophysiological knowledge with softer or harder constraints. It is continuing research to determine which prior knowledge added is better suited in each situation and there is a need to compare different methods on the same dataset to resolve that question. Here we compare two temporal methods that lie at both sides of the softness/hardness imposition of the prior knowledge. In one hand the splines method by Erem et al. imposes smoothness on the solution, while the cardiac isochrone positioning system (CIPS) forces the solutions to be step-function shaped in time. For this comparison we use the PSTOV dataset from the consortium on electrocardiographic imaging www.ecg-imaging. org which consists of body surface data during pacing at endocardial sites from subjects with healthy ventricles. The results show that on average CIPS performs better than the splines method, although there is too high a degree of variability within and across subjects and pacing locations to be able to predict which method performs better in an individual case.