Synchrony in Cardiac Conduction: Assessing the Effects of Pacing on Cardiac Performance Through Magnetic Resonance Imaging and Advanced ECG-imaging

Rationale Right ventricular pacing (RVP) is an established and effective therapy for patients with atrioventricular (AV) block. However, frequent RVP has been associated with left ventricular (LV) dyssynchrony and may progess heart failure. Conduction system pacing (CSP), a recently introduced alternative to RVP, aims to preserve physiological ventricular activation by engaging the heart's native conduction system. CSP includes diverse pacing approaches such as selective or non-selective His-bundle pacing, selective left bundle pacing, and LV-septal pacing, each with varying levels of fidelity in reproducing normal conduction. The mechanical impact of these distinct CSP strategies on left and right ventricular (RV) performance remains poorly understood. Cardiac magnetic resonance imaging (CMR), a non-invasive and highly accurate tool for assessing cardiac structure and function, is uniquely positioned to elucidate the effects of CSP and RVP on cardiac performance. This trial aims to evaluate the comparative mechanical effects of these pacing strategies, potentially identifying the optimal approach for improving outcomes in patients with AV block. Objective To investigate and compare the effects of CSP and RVP on cardiac performance, as assessed by CMR and electrocardiographic imaging (ECG-imaging). Main Trial Endpoints The primary endpoints are measures of LV and RV performance assessed via CMR, including: ventricular volumes, ejection fraction (EF), and myocardial strain Secondary Trial Endpoints Secondary endpoints include: Safety and Feasibility: * Adverse events (e.g., troponin release, lead displacement, arrhythmias, heart failure). * Technical feasibility (e.g., ease of device implantation, ability to maintain proper pacing). Electrophysiological Assessment: * Degree of selectivity in engaging the native conduction system. * Ventricular activation times as assessed by ECG-imaging. Trial Design This is a randomized, controlled, single blind, two-cente