Evaluation of the non-invasive localization accuracy of cardiac arrhythmias attainable by multichannel magnetocardiography (MCG)

Abstract

The accuracy of multichannel magnetocardiography (MCG) for the non-invasive localization of cardiac arrhythmias was investigated. A non-magnetic catheter was used in phantom studies and for cardiac pacing of 6 patients. In a clinical setting, 32 patients with WPW-syndrome, 37 patients with premature ventricular complexes and 12 patients with ventricular tachycardia were studied and the MCG results compared to reference methods, including invasive electrophysiological mapping. Phantom and pacing studies demonstrated the spatial localization accuracy to be better than 15 mm for a dipole-to-dewar distance below 15 cm. In all patients with structural cardiac disease, the ectopic focus was localized at the margin of the damaged area, serving as a proof of MCG localization. Invasive mapping confirmed the MCG result whenever performed (42 patients). In 11 patients (9 WPW, 2 VT) the MCG localization result was verified by successful HF catheter ablation as a gold standard. MCG permits the non-invasive localization of cardiac arrhythmias with high spatial accuracy. MCG guided HF catheter ablation constitutes a new concept of non-invasive localization and minimally invasive causal therapy.

Magnetocardiographic localization of arrhythmia substrates: a methodology study with accessory pathway ablation as reference

“…The box model (mean 3-D error of 36 mm) was better than the halfspace, but not as good as the sphere. (Table I) The present results are somewhat different from those of previous studies, which in the clinical setting, most often have used the infinite halfspace and found the error to be in the range 18-73 mm [7], [11], [13]- [16], [18], [20]. A strict comparison is, however, difficult since some earlier studies applied other reference methods such as standard ECG [16], body surface mapping, coronary sinus mapping [7], [13]- [16], epicardial intraoperative mapping [16], [17], [19], radionuclide ventriculography [7] and temporary pacing site [21], while we have used the best presently available clinical reference method, i.e., the site of successful RF-ablation.…”

Current Status and Future of Cardiac Mapping in Atrial Fibrillation

“…MCG has proven accurate in localization of accessory pathways causing pre-excitation in Wolff-Parkinson-White syndrome [64], as well as in localization of the tachycardia points of origin [65] and premature ventricular ectopic complexes [66]. MCG have been superior to signal-averaged ECG in indicating a propensity toward life-threatening arrhythmias and magnetocardiographic intra-QRS fragmentation [67] and QT dispersion have identified post-MI patients prone to ventricular arrhythmias [68], the former being independent of the extent of LV dysfunction.…”

Special article Magnetocardiography in clinical cardiology. Status quo and future applications

“…However, in 1998, using the Helsinki multichannel system with an acceptable signal-to-noise ratio, Fenici et al demonstrated that MCG is an effective clinical tool for non-invasive threedimensional electro-anatomical imaging [41]. Accurate localization of the accessory pathway has been successfully performed in patients with Wolf-ParkinsonWhite (WPW) syndrome [42][43][44][45][46]. In these studies the accuracy of the non-invasive MCG localization of arrhythmogenic substrates has been evaluated by comparison with the results of conventional invasive catheter mapping.…”