Abstract 15656: Noninvasive Evaluation of Benign and Malignant Early Repolarization With a New Concept of Late Potentials in the High Resolution Magnetocardiography
Most of the early repolarization patterns (ERP) are benign, but sometimes arrhythmogenic, leading to sudden cardiac death (SCD). We hypothesized high spatio-temporal resolution magnetocardiography (MCG) can non-invasively detect the malignant ERP.
Methods: Sixty four-channel MCG, standard 12-lead ECG, and signal averaged ECG (SAECG) were recorded in 45 subjects with ERP in inferolateral leads and without any organic heart disease (45±16 years old, 31 male, 11 had history of VF), and 33 healthy controls (34±8 years old, 27 male). In the 64-channel MCG current map, left ventricular area was detected by the maximal current in the whole cardiac cycle, and the current information there was evaluated. Referring to the concept of late potentials (LP) in SAECG, we defined and evaluated the following three indexes; MCG-QRS (ms), root mean square amplitude ratio of terminal 40ms (MCG-RMS40), and duration of low amplitude signal under 10% of maximal amplitude (MCG-LAS10) (ms) (Figure 1).
Results: The QRS, QT interval, amplitude and distribution of the J-wave and ST-T morphology of ECG, and familial history of SCD were not associated with VF events. None the VF subjects showed positive LP in SAECG. However, they presented a significantly longer MCG-QRS (114±24 vs. 96±26 ms; p <0.05), smaller MCG-RMS40 (0.08±0.07 vs. 0.22±0.15; p <0.01) and longer MCG-LAS10 (46±21 vs. 30±23 ms; p=0.05), compared to non-VF ERP or control subjects. We further defined MCG-LP positive when more than two of the three MCG categories (QRS >100ms, RMS40 <0.1, LAS10 >50ms) were applicable. Positive MCG-LP was observed in 72% (8/11) of the VF patients, but 14~15% of the ERP or control subjects. In the ERP subjects, positive MCG-LP (n=13) was significantly associated with VF events (p=0.004, Figure 2).
Conclusions: A new concept of MCG-LP might have a potential to distinguish the malignant ERP from the majority of the benign ones. Further prospective study with long-term follow up is necessary to be investigated.
- © 2013 by American Heart Association, Inc.