Clinical Validation of Three-Dimensional Cardiac Magnetic Source Imaging Accuracy with Simultaneous Magnetocardiographic Mapping, Monophasic Action Potential Recordings and Amagnetic Cardiac Pacing

This study validates, in patients., the accuracy of magnetocardiographic mapping (MCG) for three-dimensional (3D) localization of cardiac sources. A specially designed amagnetic catheter (AC), which tip generates current dipoles of different geometry and records monophasic action potential (MAP), was inserted in 10 patients, after routine EPS. Four MAPs were simultaneously recorded with the AC, to monitor the stability of endocardial contact before, during and after the MCG. The position of AC’tip was also imaged by biplane fluoroscopy (XR), together with lead markers. MCG studies were performed in the BioMag magnetically shielded room at. Current dipoles (5mm; 10mA) were activated at the AC’tip. For the MCG localizations of the AC’tip, the equivalent current dipole (ECD) model in patient-specific boundary element torso was used. The accuracy of the MCG localizations was evaluated by: 1) anatomical location of ECD in MRI, 2) mismatch with XR, 3) coherence between the localizations of AC’dipole and evoked myocardial response after 3 ms. The AC was in stable endocardial contact and was correctly localized in the right ventricle of all patients MRI. The mean 3D distance between XR and MCG localizations was 5±3 mm. The mean difference between the MCG localizations at the peak of the stimulus and 3 ms later was 41 mm. The 95% confidence interval of beat-to-beat localizations of AC’tip was 4±3 mm. With a sufficient signal-to-noise ratio, 3D dipole localizations of both stimulus spikes and evoked responses were accurate and reproducible. Thus MCG localizes cardiac sources with accuracy good enough for clinical applications.