Abstract 11668: High Resolution Magnetocardiography as a Novel Noninvasive Tool to Distinguish Between Benign and Malignant Early Repolarization Pattern

Abstract

Introduction: Most of the early repolarization patterns (ERP) in electrocardiography (ECG) are benign but some of them are associated with ventricular fibrillation (VF). We evaluated whether or not a high spatio-temporal resolution magnetocardiography (MCG) could non-invasively detect malignant types of ERP. Methods: Sixty four-channel MCG, standard 12-lead ECG, and signal averaged ECG (SAECG) were recorded in 120 patients with inferolateral ERP in ECG without any major structural heart diseases; 13 of them had a history of VF (VF(+)-group) and the remaining 107 had no VF (VF(-)-group). We evaluated the following novel MCG indexes: MCG-QRS (msec), root mean square of terminal 40 msec magnetic field (MCG-RMS) (msec), and the duration under 10% of maximal amplitude (MCG-LAS) (msec) of the highest amplitude channel. Results: The amplitude and distribution of the J-wave, ST-T morphology in ECG, parameters of SAECG were not significantly different, whereas MCG-QRS and MCG-LAS were significantly longer and MCG-RMS was smaller in ERP-VF(+) compared with ERP-VF(-) group (107(SD=24) vs 84(13) msec, P<0.01, 8(22) vs 22(11) msec, P<0.01, 0.10(0.08) vs 0.28(0.19) msec, P<0.01, respectively). In the multivariate logistic regression model, only MCG-QRS remained significant among the MCG indexes and the existing predictors (odds ratio (OR) 1.08, 95%CI 1.01 to1.17). The predictive ability of VF was significantly higher using MCG-QRS when the c-statistic was compared with that of the existing ECG measure (0.82 vs 0.56, P<0.01, Figure). When cut-offs were set by the least squares method at MCG-QRS 100 msec, MCG-RMS 0.24 msec, MCG-LAS 27 msec, corresponding ORs were calculated as 12.7, 95%CI 3.6 to 45.0, 6.1, 95%CI 1.7 to 21.2, 6.2, 95%CI 1.8 to 20.8, respectively. Conclusions: MCG-QRS >100 msec was a simple and effective criterion for prediction of high risk ERP subjects, thus MCG analysis is an useful screening tool to detect malignant ERP out of the numerous benign ones.