Clinical Evaluation of Non-Invasive Mapping of Premature Ventricular Contractions by Merging Magnetocardiography and Computed Tomography

Abstract

Magnetocardiography（MCG）, a diagnostic modality that measures the magnetic field of the heart, has good spatial resolution because transparency of magnetic field signals is generally constant and not influenced by various tissues in the human body, so this modality could potentially help diagnose arrhythmia more accurately than the electrocardiogram（ECG）. The utility of MCG in discriminating premature ventricular contractions（PVCs）originating from the right ventricular outflow tract from those originating from the aortic sinus cusps was previously reported. To further improve the diagnostic accuracy of MCG mapping, we recently developed a method that merges MCG images with computed tomography（CT）images. This study aimed to evaluate our novel non-invasive MCG mapping method merged with computed tomography（MCG-CT）for PVCs. The study included 22 patients referred for catheter ablation of idiopathic PVCs. Radiopaque L-shaped acrylic markers during CT scanning and coil markers generating a weak magnetic field during MCG measurements were used as reference markers to merge the images. Estimated PVC origins determined by using a spatial filter algorithm applied to MCG data were merged with the 3-D CT image by matching the coordinates of each marker. These MCG-CT mapping images were compared with the successful ablation sites obtained from the CARTO system, and diagnostic accuracy was evaluated. The accuracy of MCG-CT mapping was 94％, which was higher than that of ECG algorithms（72％）. The high diagnostic accuracy of this method may allow us to use MCG-CT mapping in clinical practice.