Comparison of magnetocardiography and electrocardiography: a study of automatic measurement of dispersion of ventricular repolarization.

AIMS There is some dispute over the clinical significance of dispersion of ventricular repolarization measurements from the electrocardiogram. Recent studies have indicated that multichannel magnetocardiograms (MCGs), which non-invasively measure cardiac magnetic field strength from many sites above the body surface, may provide independent information from ECGs about ventricular repolarization dispersion. For this study, magnetocardiography and electrocardiography were compared from automatic measurements of dispersion of ventricular repolarization. METHODS AND RESULTS Dispersion of ventricular repolarization time was determined in MCGs and standard ECGs recorded simultaneously from 27 healthy volunteers and 22 cardiac patients. Two automatic techniques were used to determine the interval of ventricular repolarization. There were significant differences in ventricular dispersion between ECG and MCG measurements, with multichannel MCG greater than ECG by 52 (47) ms [mean (SD)] (P<0.00001) and 12-channel MCG greater by 17 (40) ms (P<0.004) across techniques and all subjects. Magnetocardiograms had the greater discriminating power between normal and cardiac patients with differences of 46 (18) ms (P<0.017) for multichannel MCG and 44 (16) ms (P<0.005) for 12-channel MCG, compared with 16 (7) ms (P<0.04) for ECG. CONCLUSION Magnetocardiography has the power to discriminate regional cardiac conduction differences.