In silico systematic evaluation of the scar effect in conventional and new cardiac resynchronization therapy approaches

• LBBAP and LOT-CRT improves electrical biomarkers versus conventional CRT. • Fusion pacing improves therapy outcome in conventional and newer CRT approaches. • Benefits of conventional and new CRT approaches depends on scar location. • Purkinje system survivability in the scar changes cardiac activation and CRT outcome. Cardiac resynchronization therapy (CRT) is a technique used in the clinical setting to solve dyssynchronization problems in ventricular contraction. The goal of this study was to evaluate in silico the performance of conventional and new CRT approaches under left bundle branch block (LBBB) and heart failure (HF) conditions, and especially under myocardial scar presence. The simulations were run in a 3D realistic biventricular model including the His-Purkinje system, where the different pathologies were modeled. Stimulation protocols corresponding to each of the CRT approaches assessed were applied. Importantly, the presence of infarcted tissue was systematically evaluated according to the American Heart Association segmentation of the heart. To assess CRT performance, a set of six biomarkers obtained from simulated ECG signals and activation maps was defined. Our simulations showed that under LBBB and HF conditions with or without infarction scar, the newer CRT approaches performed better. Interestingly, the inclusion of scarred tissue in some basal and septal segments had detrimental effects on the biomarkers that particularly worsened when Purkinje fibers were considered as non-conductive. This study sheds light on the effects that several heart disruptions have in cardiac activation before and after traditional and newest CRT methods. Moreover, the utilization of fusion pacing and Purkinje fibers survivability post-infarction, has demonstrated an improvement in the overall outcome of CRT. In silico models could constitute a powerful tool to understand, evaluate, and optimize different CRT approaches, which could help clinicians to plan personalized CRT procedures and reduce patient’s risk.