Feasibility of Non-Invasive Atrial and Ventricular Activation, Conduction-Velocity, and Site-of-Origin Mapping with Solid-State Magnetocardiography: A Preclinical Validation Study

Background: Characterizing cardiac activation by its site of origin, propagation, and conduction velocity underlies arrhythmia diagnosis and management, but invasive electrophysiology (EP) mapping requires vascular access, fluoroscopy, and sedation. Magnetocardiography (MCG) enables contactless mapping, and recent solid-state sensors remove the cost, cryogenic, and shielding barriers of legacy systems. We assessed the feasibility of a novel solid-state MCG system for noninvasive arrhythmia site-of-origin (SOO) localization and activation reconstruction, benchmarked against electrocardiographic imaging (ECGi). Methods: In nine swine implanted with right atrial and right ventricular pacing leads, we recorded MCG and ECGi simultaneously during atrial and ventricular pacing. Invasive epicardial contact EP mapping provided the activation-time reference and MRI-derived lead-tip location the SOO reference. Local activation time (LAT), conduction velocity (CV), and SOO were compared on a co-registered chamber mesh. SOO error was the Euclidean distance to the MRI lead tip; LAT and CV agreement with EP were quantified by Pearson r and compared using Wilcoxon signed-rank tests. Results: Across 17 datasets (8 atrial, 9 ventricular), median SOO error was lower for MCG than ECGi in the atrium (19.6 vs 31.2 mm; p=0.023) and ventricle (12.0 vs 26.1 mm; p=0.074). LAT agreement with EP was comparable between modalities and higher in the ventricle (MCG r=0.63; ECGi r=0.68) compared with the atrium (MCG r=0.40; ECGi r=0.53), each correlating with invasive EP mapping above chance. CV agreement was modest and numerically higher for MCG in the ventricle. Conclusions: Solid-state MCG was feasible for noninvasive site-of-origin localization and activation mapping, with accuracy comparable to ECGi, motivating larger prospective studies to define its clinical role in noninvasive mapping.