## 5 Conclusions  
A meshless modeling pipeline to simulate cardiac electrical patterns in CRT was compared to FEM-based alternatives, providing equivalent results on fitting experimental data available from the CRT-EPiggy19 challenge. The main advantage of the meshless model is the independence from the usually arduous patient-specific meshing process, one of the most important bottlenecks of translating computational models into a clinical environment. However, the most relevant aspect for accurate CRT predictions was the chosen parameter personalization strategy rather than the geometrical discretization. In particular, the regional conduction velocity distribution was key, requiring at least five different regions and ideally including a PK label. A larger number of regions was associated with better data fitting but higher computational costs and more risk of overfitting. Additionally, the optimal CRT configuration was found with apical RV and basal LV leads, as reported in the literature. Despite the uniqueness of the CRT-EPiggy19 challenge dataset, data uncertainty was high in some cases due to challenging EAM acquisition and processing, which could lead to the estimation of non-physiological parameters and the requirement of prior constraints in the optimization algorithm. Nevertheless, having several teams of modeling researchers working on the same data have been beneficial for each challenge participant, jointly improving the different modeling solutions. Conceptualization, C.A., J.F.G., N.C., K.A.M., T.M., S.K., A.D., O.S., E.P., M.S., R.S., H.G.M. and O.C. ; Data curation, T.M. ; Formal analysis, C.A., J.F.G., N.C., K.A.M., S.K., A.D., O.S., E.P., M.S. and R.S. ; Investigation, C.A., J.F.G., N.C., K.A.M., S.K., A.D., O.S., E.P., M.S. and O.C. ; Methodology, C.A., J.F.G., N.C., K.A.M., S.K., A.D., O.S., E.P., M.S. and R.S. ; Project administration, O.C. ; Software, E.L. and H.G.M. ; Supervision, O.S., E.P., M.S., R.S. and O.C. ; Writing--original draft, C.A., J.F.G., N.C., K.A.M., S.K., A.D., O.S., E.P., M.S., R.S. and O.C. ; Writing--review & editing, C.A. and O.C. All authors have read and agreed to the published version of the manuscript. This work was supported in part by the Spanish Ministry of Science and Innovation (TIN2011-28067, REDINSCOR RD06/003/008, PID2019-105674 RB-I00), the Spanish Industrial and Technological Development Center (cvREMOD-CEN-20091044), the Spanish Ministry of Economy and Competitiveness under the Maria de Maeztu Units of Excellence Programme (MDM-2015-0502), the Government of Aragon (Spain) (LMP94_21), the Directorate General of Science Policy of the Generalitat Valenciana (Spain) (PROMETEU 2016/088), the Seventh Framework Programme (FP7/2007-2013) for research, technological and demonstration under grant agreement VP2 HF (no. 611823), by the RSF grant no. 19-14-00134, and by European Regional Development Fund (ERDF) DPI2016-75799-R (AEI/ERDF, EU). **Institutional Review Board Statement**: The present manuscript was based on a subset of the data from the experimental study conducted by [PERSON] et al. [24] at Hospital Clinic de Barcelona in which animal handling was approved by the Institutional Review Board and Ethics Committee (approval reference number: DMAH 5648). Additional information can be found at: [PERSON], [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON], [PERSON] [PERSON] Development of a swine model of left bundle branch block for experimental studies of cardiac resynchronization therapy. J Cardiovasc Transl Res. 2013 Aug;6(4):616-22. doi: 10.1007/s12265-013-9464-1. **Conflicts of Interest**: The authors declare no conflict of interest. Figure 10: **Local activation time maps for the infarcted case, Pig 3, of the training database in left bundle branch block (LBBB) and cardiac resynchronization therapy (CRT) conditions, provided by the (a) electroanatomical measurements (EAM) and the (b,c) meshless (SPH) model.